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111-476: Honey is a sweet and viscous substance made by several species of bees , the best-known of which are honey bees . Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primarily floral nectar ) or the secretions of other insects, like the honeydew of aphids. This refinement takes place both within individual bees, through regurgitation and enzymatic activity, and during storage in

222-439: A Maillard reaction . The Maillard reaction occurs slowly at room temperature, taking from a few to several months to show visible darkening, but speeds up dramatically with increasing temperatures. However, the reaction can also be slowed by storing the honey at colder temperatures. Unlike many other liquids, honey has very poor thermal conductivity of 0.5 W/(m⋅K) at 13% water content (compared to 401 W/(m⋅K) of copper ), taking

333-462: A glassy state and becomes an amorphous solid (noncrystalline). The viscosity of honey is affected greatly by both temperature and water content. The higher the water percentage, the more easily honey flows . Above its melting point, however, water has little effect on viscosity. Aside from water content, the composition of most types of honey also has little effect on viscosity. At 25 °C (77 °F), honey with 14% water content generally has

444-435: A magnetic field , possibly to the point of behaving like a solid. The viscous forces that arise during fluid flow are distinct from the elastic forces that occur in a solid in response to shear, compression, or extension stresses. While in the latter the stress is proportional to the amount of shear deformation, in a fluid it is proportional to the rate of deformation over time. For this reason, James Clerk Maxwell used

555-453: A refractometer . Typically, the refractive index for honey ranges from 1.504 at 13% water content to 1.474 at 25%. Honey also has an effect on polarized light , in that it rotates the polarization plane. The fructose gives a negative rotation, while the glucose gives a positive one. The overall rotation can be used to measure the ratio of the mixture. Honey is generally pale yellow and dark brown in color, but other colors can occur, depending on

666-595: A supercooled solution of various sugars in water. These concentrations of sugar can only be achieved near room temperature by evaporation of a less concentrated solution, in this case nectar. For osmotic reasons such high concentrations of sugar are extremely unfavorable to microbiological reproduction and all fermentation is consequently halted. The bees then cap the cells of finished honey with wax. This seals them from contamination and prevents further evaporation. So long as its water concentration does not rise much above 18%, honey has an indefinite shelf life, both within

777-436: A constant viscosity ( non-Newtonian fluids ) cannot be described by a single number. Non-Newtonian fluids exhibit a variety of different correlations between shear stress and shear rate. One of the most common instruments for measuring kinematic viscosity is the glass capillary viscometer. In coating industries, viscosity may be measured with a cup in which the efflux time is measured. There are several sorts of cup—such as

888-502: A fluid, just as thermal conductivity characterizes heat transport, and (mass) diffusivity characterizes mass transport. This perspective is implicit in Newton's law of viscosity, τ = μ ( ∂ u / ∂ y ) {\displaystyle \tau =\mu (\partial u/\partial y)} , because the shear stress τ {\displaystyle \tau } has units equivalent to

999-551: A food for their larvae . To this end bees stockpile honey to provide for themselves during ordinary foraging as well as during lean periods, as in overwintering . During foraging bees use part of the nectar they collect to power their flight muscles. The majority of nectar collected is not used to directly nourish the insects but is instead destined for regurgitation , enzymatic digestion , and finally long-term storage as honey. During cold weather or when other food sources are scarce, adult and larval bees consume stored honey, which

1110-491: A gel-like state when motionless, but liquefy when stirred. Because honey contains electrolytes , in the form of acids and minerals, it exhibits varying degrees of electrical conductivity . Measurements of the electrical conductivity are used to determine the quality of honey in terms of ash content. The effect honey has on light is useful for determining the type and quality. Variations in its water content alter its refractive index . Water content can easily be measured with

1221-465: A honey, which may be described as "sweet", "flowery", "citrus", "almond" or "rancid", among other terms. In addition, VOCs play a large role in determining the specific flavor of the honey, both through the aromas and flavor. VOCs from honeys in different geographic regions can be used as floral markers of those regions, and as markers of the bees that foraged the nectars. Honey is classified by its source (floral or not), and divisions are made according to

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1332-683: A long and varied history, with its beginnings in prehistoric times . Several cave paintings in Cuevas de la Araña in Spain depict humans foraging for honey at least 8,000 years ago. While Apis mellifera is an Old World insect , large-scale meliponiculture of New World stingless bees has been practiced by Mayans since pre-Columbian times. Honey is produced by bees who have collected nectar or honeydew . Bees value honey for its sugars, which they consume to support general metabolic activity , especially that of their flight muscles during foraging , and as

1443-414: A long time to reach thermal equilibrium . Due to its high kinematic viscosity honey does not transfer heat through momentum diffusion ( convection ) but rather through thermal diffusion (more like a solid), so melting crystallized honey can easily result in localized caramelization if the heat source is too hot or not evenly distributed. However, honey takes substantially longer to liquefy when just above

1554-415: A momentum flux , i.e., momentum per unit time per unit area. Thus, τ {\displaystyle \tau } can be interpreted as specifying the flow of momentum in the y {\displaystyle y} direction from one fluid layer to the next. Per Newton's law of viscosity, this momentum flow occurs across a velocity gradient, and the magnitude of the corresponding momentum flux

1665-436: A possible fire), making them less aggressive, and obscures the pheromones the bees use to communicate. The honeycomb is removed from the hive and the honey may be extracted from it either by crushing or by using a honey extractor . The honey is then usually filtered to remove beeswax and other debris. Before the invention of removable frames, bee colonies were often sacrificed to conduct the harvest. The harvester would take all

1776-621: A primary role in determining honey flavors and aromas . VOCs are carbon-based compounds that readily vaporize into the air, providing aroma, including the scents of flowers, essential oils, or ripening fruit. The typical chemical families of VOCs found in honey include hydrocarbons , aldehydes , alcohols , ketones , esters , acids , benzenes , furans , pyrans , norisoprenoids , and terpenes , among many others and their derivatives. The specific VOCs and their amounts vary considerably between different types of honey obtained by bees foraging on different plant sources. By example, when comparing

1887-416: A solution of fructose and other ingredients. The density of honey typically ranges between 1.38 and 1.45 kg/L at 20 °C. The melting point of crystallized honey is between 40 and 50 °C (104 and 122 °F), depending on its composition. Below this temperature, honey can be either in a metastable state, meaning that it will not crystallize until a seed crystal is added, or, more often, it

1998-416: A specific fluid state. To standardize comparisons among experiments and theoretical models, viscosity data is sometimes extrapolated to ideal limiting cases, such as the zero shear limit, or (for gases) the zero density limit. Transport theory provides an alternative interpretation of viscosity in terms of momentum transport: viscosity is the material property which characterizes momentum transport within

2109-461: A viscosity around 400  poise , while a honey containing 20% water has a viscosity around 20 poise. Viscosity increases very slowly with moderate cooling; a honey containing 16% water, at 70 °C (158 °F), has a viscosity around 2 poise, while at 30 °C (86 °F), the viscosity is around 70 poise. With further cooling, the increase in viscosity is more rapid, reaching 600 poise at around 14 °C (57 °F). However, while honey

2220-411: A viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow,

2331-649: Is 1 cP divided by 1000 kg/m^3, close to the density of water. The kinematic viscosity of water at 20 °C is about 1 cSt. The most frequently used systems of US customary, or Imperial , units are the British Gravitational (BG) and English Engineering (EE). In the BG system, dynamic viscosity has units of pound -seconds per square foot (lb·s/ft ), and in the EE system it has units of pound-force -seconds per square foot (lbf·s/ft ). The pound and pound-force are equivalent;

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2442-457: Is a linear combination of the shear and bulk viscosities that describes the reaction of a solid elastic material to elongation. It is widely used for characterizing polymers. In geology , earth materials that exhibit viscous deformation at least three orders of magnitude greater than their elastic deformation are sometimes called rheids . Viscosity is measured with various types of viscometers and rheometers . Close temperature control of

2553-462: Is a calculation derived from tests performed on drilling fluid used in oil or gas well development. These calculations and tests help engineers develop and maintain the properties of the drilling fluid to the specifications required. Nanoviscosity (viscosity sensed by nanoprobes) can be measured by fluorescence correlation spectroscopy . The SI unit of dynamic viscosity is the newton -second per square meter (N·s/m ), also frequently expressed in

2664-550: Is a viscosity tensor that maps the velocity gradient tensor ∂ v k / ∂ r ℓ {\displaystyle \partial v_{k}/\partial r_{\ell }} onto the viscous stress tensor τ i j {\displaystyle \tau _{ij}} . Since the indices in this expression can vary from 1 to 3, there are 81 "viscosity coefficients" μ i j k l {\displaystyle \mu _{ijkl}} in total. However, assuming that

2775-414: Is also affected by water content, because a high percentage of water inhibits crystallization, as does a high dextrin content. Temperature also affects the rate of crystallization, with the fastest growth occurring between 13 and 17 °C (55 and 63 °F). Crystal nuclei (seeds) tend to form more readily if the honey is disturbed, by stirring, shaking, or agitating, rather than if left at rest. However,

2886-532: Is called the rate of shear deformation or shear velocity , and is the derivative of the fluid speed in the direction parallel to the normal vector of the plates (see illustrations to the right). If the velocity does not vary linearly with y {\displaystyle y} , then the appropriate generalization is: where τ = F / A {\displaystyle \tau =F/A} , and ∂ u / ∂ y {\displaystyle \partial u/\partial y}

2997-407: Is collected from wild bee colonies or from domesticated beehives. On average, a hive will produce about 29 kilograms (65 lb) of honey per year. Wild bee nests are sometimes located by following a honeyguide bird. To safely collect honey from a hive, beekeepers typically pacify the bees using a bee smoker . The smoke triggers a feeding instinct (an attempt to save the resources of the hive from

3108-558: Is commonly used in modern mead production. Mead varieties include drinks called metheglin (with spices or herbs), melomel (with fruit juices, such as grape, specifically called pyment ), hippocras (with cinnamon ), and sack mead (high concentration of honey), many of which have been developed as commercial products numbering in the hundreds in the United States. Honey is also used to make mead beer , called "braggot". The physical properties of honey vary, depending on water content,

3219-453: Is derived from the Latin viscum (" mistletoe "). Viscum also referred to a viscous glue derived from mistletoe berries. In materials science and engineering , there is often interest in understanding the forces or stresses involved in the deformation of a material. For instance, if the material were a simple spring, the answer would be given by Hooke's law , which says that

3330-448: Is determined by the viscosity. The analogy with heat and mass transfer can be made explicit. Just as heat flows from high temperature to low temperature and mass flows from high density to low density, momentum flows from high velocity to low velocity. These behaviors are all described by compact expressions, called constitutive relations , whose one-dimensional forms are given here: where ρ {\displaystyle \rho }

3441-534: Is equal to the SI millipascal second (mPa·s). The SI unit of kinematic viscosity is square meter per second (m /s), whereas the CGS unit for kinematic viscosity is the stokes (St, or cm ·s = 0.0001 m ·s ), named after Sir George Gabriel Stokes . In U.S. usage, stoke is sometimes used as the singular form. The submultiple centistokes (cSt) is often used instead, 1 cSt = 1 mm ·s  = 10  m ·s . 1 cSt

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3552-592: Is in a "labile" state, being saturated with enough sugars to crystallize spontaneously. The rate of crystallization is affected by many factors, but the primary factor is the ratio of the main sugars: fructose to glucose. Honeys that are supersaturated with a very high percentage of glucose, such as brassica honey, crystallize almost immediately after harvesting, while honeys with a low percentage of glucose, such as chestnut or tupelo honey, do not crystallize. Some types of honey may produce few but very large crystals, while others produce many small crystals. Crystallization

3663-576: Is in terms of the standard (scalar) viscosity μ {\displaystyle \mu } and the bulk viscosity κ {\displaystyle \kappa } such that α = κ − 2 3 μ {\displaystyle \alpha =\kappa -{\tfrac {2}{3}}\mu } and β = γ = μ {\displaystyle \beta =\gamma =\mu } . In vector notation this appears as: where δ {\displaystyle \mathbf {\delta } }

3774-412: Is in their own honey stomachs, the hive bees regurgitate the nectar, repeatedly forming bubbles between their mandibles , speeding its digestion and concentration. These bubbles create a large surface area per volume and by this means the bees evaporate a portion of the nectar's water into the warm air of the hive. Hive bees form honey-processing groups. These groups work in relay, with one bee subjecting

3885-440: Is inwardly concave, thus forming a central tube up which moisture is sucked. Suction takes place due to the contraction and expansion of a sac in the head. A specific example of the proboscis being used for feeding is in the species Deilephila elpenor . In this species, the moth hovers in front of the flower and extends its long proboscis to attain its food. A few Lepidoptera species lack mouth parts and therefore do not feed in

3996-603: Is limiting access to humidity. In its cured state, honey has a sufficiently high sugar content to inhibit fermentation. If exposed to moist air, its hydrophilic properties pull moisture into the honey, eventually diluting it to the point that fermentation can begin. The long shelf life of honey is attributed to an enzyme found in the stomach of bees. The bees mix glucose oxidase with expelled nectar they previously consumed, creating two byproducts – gluconic acid and hydrogen peroxide , which are partially responsible for honey acidity and suppression of bacterial growth. Honey

4107-436: Is many times as energy-dense as the nectar from which it is made. After leaving the hive, a foraging bee collects sugar-rich nectar or honeydew. Nectar from the flower generally has a water content of 70 to 80% and is much less viscous than finished honey, which usually has a water content around 18%. The water content of honeydew from aphids and other true bugs is generally very close to the sap on which those insects feed and

4218-421: Is normal. At very low temperatures, honey does not freeze solid; rather its viscosity increases. Like most viscous liquids , the honey becomes thick and sluggish with decreasing temperature. At −20 °C (−4 °F), honey may appear or even feel solid, but it continues to flow at very low rates. Honey has a glass transition between −42 and −51 °C (−44 and −60 °F). Below this temperature, honey enters

4329-658: Is not a fundamental law of nature, but rather a constitutive equation (like Hooke's law , Fick's law , and Ohm's law ) which serves to define the viscosity μ {\displaystyle \mu } . Its form is motivated by experiments which show that for a wide range of fluids, μ {\displaystyle \mu } is independent of strain rate. Such fluids are called Newtonian . Gases , water , and many common liquids can be considered Newtonian in ordinary conditions and contexts. However, there are many non-Newtonian fluids that significantly deviate from this behavior. For example: Trouton 's ratio

4440-462: Is observed only at very low temperatures in superfluids ; otherwise, the second law of thermodynamics requires all fluids to have positive viscosity. A fluid that has zero viscosity (non-viscous) is called ideal or inviscid . For non-Newtonian fluid 's viscosity, there are pseudoplastic , plastic , and dilatant flows that are time-independent, and there are thixotropic and rheopectic flows that are time-dependent. The word "viscosity"

4551-597: Is preferred because all bee colonies, even those in very large agricultural apiculture operations, readily leave the protection of humans in swarms that can establish successful wild colonies. Much of the effort in commercial beekeeping is dedicated to persuading a hive that is ready to swarm to produce more honeycomb in its present location. This is usually done by adding more space to the colony with honey supers , empty boxes placed on top of an existing colony. The bees can then usually be enticed to develop this empty space instead of dividing their colony through swarming. Honey

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4662-441: Is sometimes adulterated by the addition of other sugars, syrups, or compounds to change its flavor or viscosity, reduce cost, or increase the fructose content to inhibit crystallization . Honey has been adulterated since ancient times, when honey was sometimes blended with plant syrups such as maple , birch , or sorghum and sold to customers as pure honey. Sometimes crystallized honey was mixed with flour or other fillers, hiding

4773-599: Is sweet because of its high concentrations of the monosaccharides fructose and glucose . It has about the same relative sweetness as sucrose (table sugar). One standard tablespoon (15 mL) of honey provides around 190 kilojoules (46 kilocalories) of food energy . It has attractive chemical properties for baking and a distinctive flavor when used as a sweetener. Most microorganisms cannot grow in honey and sealed honey therefore does not spoil . Samples of honey discovered in archaeological contexts have proven edible even after millennia. Honey use and production has

4884-581: Is the dynamic viscosity of the fluid, often simply referred to as the viscosity . It is denoted by the Greek letter mu ( μ ). The dynamic viscosity has the dimensions ( m a s s / l e n g t h ) / t i m e {\displaystyle \mathrm {(mass/length)/time} } , therefore resulting in the SI units and the derived units : The aforementioned ratio u / y {\displaystyle u/y}

4995-408: Is the density, J {\displaystyle \mathbf {J} } and q {\displaystyle \mathbf {q} } are the mass and heat fluxes, and D {\displaystyle D} and k t {\displaystyle k_{t}} are the mass diffusivity and thermal conductivity. The fact that mass, momentum, and energy (heat) transport are among

5106-425: Is the local shear velocity. This expression is referred to as Newton's law of viscosity . In shearing flows with planar symmetry, it is what defines μ {\displaystyle \mu } . It is a special case of the general definition of viscosity (see below), which can be expressed in coordinate-free form. Use of the Greek letter mu ( μ {\displaystyle \mu } ) for

5217-606: Is the ratio of extensional viscosity to shear viscosity . For a Newtonian fluid, the Trouton ratio is 3. Shear-thinning liquids are very commonly, but misleadingly, described as thixotropic. Viscosity may also depend on the fluid's physical state (temperature and pressure) and other, external , factors. For gases and other compressible fluids , it depends on temperature and varies very slowly with pressure. The viscosity of some fluids may depend on other factors. A magnetorheological fluid , for example, becomes thicker when subjected to

5328-554: Is the unit tensor. This equation can be thought of as a generalized form of Newton's law of viscosity. The bulk viscosity (also called volume viscosity) expresses a type of internal friction that resists the shearless compression or expansion of a fluid. Knowledge of κ {\displaystyle \kappa } is frequently not necessary in fluid dynamics problems. For example, an incompressible fluid satisfies ∇ ⋅ v = 0 {\displaystyle \nabla \cdot \mathbf {v} =0} and so

5439-408: Is usually done at the lowest temperature and for the shortest time possible. The average pH of honey is 3.9, but can range from 3.4 to 6.1. Honey contains many kinds of acids, both organic and amino . However, the different types and their amounts vary considerably, depending on the type of honey. These acids may be aromatic or aliphatic (nonaromatic). The aliphatic acids contribute greatly to

5550-461: Is usually somewhat more dilute than nectar. One source describes the water content of honeydew as around 89%. Whether it is feeding on nectar or honeydew, the bee sucks these runny fluids through its proboscis , which delivers the liquid to the bee's honey stomach or "honey crop". This cavity lies just above its food stomach, the latter of which digests pollen and sugars consumed by an individual honey bee for its own nourishment. In Apis mellifera ,

5661-544: Is viscous, it has low surface tension of 50–60 mJ/m, making its wettability similar to water, glycerin , or most other liquids. The high viscosity and wettability of honey cause stickiness , which is a time-dependent process in supercooled liquids between the glass-transition temperature (T g ) and the crystalline-melting temperature. Most types of honey are Newtonian liquids , but a few types have non-Newtonian viscous properties. Honeys from heather or manuka display thixotropic properties. These types of honey enter

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5772-505: The Hadza people ranking honey as their favorite food. Honey hunters in Africa have a mutualistic relationship with certain species of honeyguide birds. Possibly the world's oldest fermented beverage , dating from 9,000 years ago, mead ("honey wine") is the alcoholic product made by adding yeast to honey-water must and fermenting it for weeks or months. The yeast Saccharomyces cerevisiae

5883-577: The Zahn cup and the Ford viscosity cup —with the usage of each type varying mainly according to the industry. Also used in coatings, a Stormer viscometer employs load-based rotation to determine viscosity. The viscosity is reported in Krebs units (KU), which are unique to Stormer viscometers. Vibrating viscometers can also be used to measure viscosity. Resonant, or vibrational viscometers work by creating shear waves within

5994-425: The density of the fluid ( ρ ). It is usually denoted by the Greek letter nu ( ν ): and has the dimensions ( l e n g t h ) 2 / t i m e {\displaystyle \mathrm {(length)^{2}/time} } , therefore resulting in the SI units and the derived units : In very general terms, the viscous stresses in a fluid are defined as those resulting from

6105-485: The imago . Others, such as the family Micropterigidae , have mouth parts of the chewing kind. The study of insect mouthparts was helpful for the understanding of the functional mechanism of the proboscis of butterflies (Lepidoptera) to elucidate the evolution of new form-function. The study of the proboscis of butterflies revealed surprising examples of adaptations to different kinds of fluid food, including nectar , plant sap , tree sap, dung and of adaptations to

6216-729: The latinisation of the Ancient Greek προβοσκίς ( proboskis ), which comes from πρό ( pro ) 'forth, forward, before' + βόσκω ( bosko ), 'to feed, to nourish'. The plural as derived from the Greek is proboscides , but in English the plural form proboscises occurs frequently. The most common usage is to refer to the tubular feeding and sucking organ of certain invertebrates such as insects (e.g., moths, butterflies , and mosquitoes), worms (including Acanthocephala , proboscis worms ) and gastropod molluscs . The Acanthocephala ,

6327-442: The nucleation of microscopic seed-crystals is greatest between 5 and 8 °C (41 and 46 °F). Therefore, larger but fewer crystals tend to form at higher temperatures, while smaller but more-numerous crystals usually form at lower temperatures. Below 5 °C, the honey will not crystallize, thus the original texture and flavor can be preserved indefinitely. Honey is a supercooled liquid when stored below its melting point, as

6438-431: The shear viscosity . However, at least one author discourages the use of this terminology, noting that μ {\displaystyle \mu } can appear in non-shearing flows in addition to shearing flows. In fluid dynamics, it is sometimes more appropriate to work in terms of kinematic viscosity (sometimes also called the momentum diffusivity ), defined as the ratio of the dynamic viscosity ( μ ) over

6549-491: The BG and EE systems. Nonstandard units include the reyn (lbf·s/in ), a British unit of dynamic viscosity. In the automotive industry the viscosity index is used to describe the change of viscosity with temperature. The reciprocal of viscosity is fluidity , usually symbolized by ϕ = 1 / μ {\displaystyle \phi =1/\mu } or F = 1 / μ {\displaystyle F=1/\mu } , depending on

6660-463: The Couette flow, a fluid is trapped between two infinitely large plates, one fixed and one in parallel motion at constant speed u {\displaystyle u} (see illustration to the right). If the speed of the top plate is low enough (to avoid turbulence), then in steady state the fluid particles move parallel to it, and their speed varies from 0 {\displaystyle 0} at

6771-570: The United States, according to the National Honey Board, "Ensuring honey authenticity is one of the great challenges facing the honey industry today. Over the past half century, a number of honey testing methods have been developed to detect food fraud. To date, there is no single universal analytical method available which is capable of detecting all types of adulteration with adequate sensitivity." Isotope ratio mass spectrometry can be used to detect addition of corn syrup and cane sugar by

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6882-538: The adulteration from buyers until the honey was liquefied. In modern times, the most common adulterant became clear, almost-flavorless corn syrup; the adulterated mixture can be very difficult to distinguish from pure honey. According to the Codex Alimentarius of the United Nations, any product labeled as "honey" or "pure honey" must be a wholly natural product, although labeling laws differ between countries. In

6993-514: The arithmetic and the reference table provided in ASTM D 2161. Proboscis A proboscis ( / p r oʊ ˈ b ɒ s ɪ s , - k ɪ s / ) is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate . In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elongated nose or snout. First attested in English in 1609 from Latin proboscis ,

7104-438: The available honey and replace the entire colony the next spring. Since the invention of removable frames, the principles of husbandry led most beekeepers to ensure that their bees have enough stores to survive the winter, either by leaving some honey in the beehive or by providing the colony with a honey substitute such as sugar water or crystalline sugar (often in the form of a "candyboard"). The amount of food necessary to survive

7215-425: The bottom to u {\displaystyle u} at the top. Each layer of fluid moves faster than the one just below it, and friction between them gives rise to a force resisting their relative motion. In particular, the fluid applies on the top plate a force in the direction opposite to its motion, and an equal but opposite force on the bottom plate. An external force is therefore required in order to keep

7326-479: The carbon isotopic signature . Addition of sugars originating from corn or sugar cane ( C4 plants , unlike the plants used by bees, and also sugar beet , which are predominantly C3 plants ) skews the isotopic ratio of sugars present in honey, but does not influence the isotopic ratio of proteins. In an unadulterated honey, the carbon isotopic ratios of sugars and proteins should match. Levels as low as 7% of addition can be detected. In 2020, global production of honey

7437-427: The colony to a site for a new hive. Bees generally swarm before a suitable location for another hive has been discovered by scouts sent out for this purpose. Until such a location is found the swarm will simply conglomerate near the former hive, often from tree branches. These swarms are unusually docile and amenable to transport by humans. When provided with a suitable nesting site, such as a commercial Langstroth hive ,

7548-446: The composition, but is typically between 70 and 110 °C (158 and 230 °F). Honey also contains acids, which act as catalysts for caramelization. The specific types of acids and their amounts play a primary role in determining the exact temperature. Of these acids, the amino acids, which occur in very small amounts, play an important role in the darkening of honey. The amino acids form darkened compounds called melanoidins , during

7659-597: The convention used, measured in reciprocal poise (P , or cm · s · g ), sometimes called the rhe . Fluidity is seldom used in engineering practice. At one time the petroleum industry relied on measuring kinematic viscosity by means of the Saybolt viscometer , and expressing kinematic viscosity in units of Saybolt universal seconds (SUS). Other abbreviations such as SSU ( Saybolt seconds universal ) or SUV ( Saybolt universal viscosity ) are sometimes used. Kinematic viscosity in centistokes can be converted from SUS according to

7770-461: The dynamic viscosity (sometimes also called the absolute viscosity ) is common among mechanical and chemical engineers , as well as mathematicians and physicists. However, the Greek letter eta ( η {\displaystyle \eta } ) is also used by chemists, physicists, and the IUPAC . The viscosity μ {\displaystyle \mu } is sometimes also called

7881-409: The environment, and in some cases, capturing prey or attaching to hosts. Three major types of proboscises have been identified: pleurembolic (partially retractable), acrembolic (fully retractable), and intraembolic (variable in structure). Acrembolic proboscises are usually found in parasitic gastropods. The elephant's trunk and the tapir 's elongated nose are called "proboscis", as is the snout of

7992-407: The equivalent forms pascal - second (Pa·s), kilogram per meter per second (kg·m ·s ) and poiseuille (Pl). The CGS unit is the poise (P, or g·cm ·s = 0.1 Pa·s), named after Jean Léonard Marie Poiseuille . It is commonly expressed, particularly in ASTM standards, as centipoise (cP). The centipoise is convenient because the viscosity of water at 20 °C is about 1 cP, and one centipoise

8103-592: The flavor of honey by interacting with the flavors of other ingredients. Organic acids comprise most of the acids in honey, accounting for 0.17–1.17% of the mixture, with gluconic acid formed by the actions of glucose oxidase as the most prevalent. Minor amounts of other organic acids are present, consisting of formic , acetic , butyric , citric , lactic , malic , pyroglutamic , propionic , valeric , capronic , palmitic , and succinic , among many others. Individual honeys from different plant sources contain over 100 volatile organic compounds (VOCs), which play

8214-494: The flora also have an effect on honey aroma properties, such as a "fruity" or "grassy" aroma from longan honey, or a "waxy" aroma from sunflower honey. Dominant VOCs in one study were linalool oxide , trans-linalool oxide, 2- phenylacetaldehyde , benzyl ethanol , isophorone , and methyl nonanoate . VOCs can also be introduced from the bodies of the bees, be produced by the enzymatic actions of digestion, or from chemical reactions that occur between different substances within

8325-409: The fluid do not depend on the distance the fluid has been sheared; rather, they depend on how quickly the shearing occurs. Viscosity is the material property which relates the viscous stresses in a material to the rate of change of a deformation (the strain rate). Although it applies to general flows, it is easy to visualize and define in a simple shearing flow, such as a planar Couette flow . In

8436-459: The fluid is essential to obtain accurate measurements, particularly in materials like lubricants, whose viscosity can double with a change of only 5 °C. A rheometer is used for fluids that cannot be defined by a single value of viscosity and therefore require more parameters to be set and measured than is the case for a viscometer. For some fluids, the viscosity is constant over a wide range of shear rates ( Newtonian fluids ). The fluids without

8547-426: The force experienced by a spring is proportional to the distance displaced from equilibrium. Stresses which can be attributed to the deformation of a material from some rest state are called elastic stresses. In other materials, stresses are present which can be attributed to the deformation rate over time . These are called viscous stresses. For instance, in a fluid such as water the stresses which arise from shearing

8658-469: The hive and after its removal by a beekeeper . Honey bees are not the only eusocial insects to produce honey. All non-parasitic bumblebees and stingless bees produce honey. Some wasp species, such as Brachygastra lecheguana and Brachygastra mellifica , found in South and Central America, are known to feed on nectar and produce honey. Other wasps, such as Polistes versicolor , also consume honey. In

8769-425: The hive, through water evaporation that concentrates the honey's sugars until it is thick and viscous. Honey bees stockpile honey in the hive . Within the hive is a structure made from wax called honeycomb . The honeycomb is made up of hundreds or thousands of hexagonal cells, into which the bees regurgitate honey for storage. Other honey-producing species of bee store the substance in different structures, such as

8880-457: The honey during storage, and therefore may change, increase, or decrease over long periods of time. VOCs may be produced, altered, or greatly affected by temperature and processing. Some VOCs are heat labile, and are destroyed at elevated temperatures, while others can be created during non-enzymatic reactions, such as the Maillard reaction . VOCs are responsible for nearly all of the aroma produced by

8991-404: The honey stomach holds about 40 mg of liquid. This is about half the weight of an unladen bee. Collecting this quantity in nectar can require visits to more than a thousand flowers. When nectar is plentiful, it can take a bee more than an hour of ceaseless work to collect enough nectar to fill its honey crop. Salivary enzymes and proteins from the bee's hypopharyngeal gland are secreted into

9102-402: The honey's water content rises much above 25%. Honey tends to absorb more water in this manner than the individual sugars allow on their own, which may be due to other ingredients it contains. Fermentation of honey usually occurs after crystallization, because without the glucose, the liquid portion of the honey primarily consists of a concentrated mixture of fructose, acids, and water, providing

9213-431: The honey-storage areas. This temperature is regulated either by generating heat with their bodies or removing it through water evaporation. The evaporation removes water from the stored honey, drawing heat from the colony. The bees use their wings to govern hive cooling. Coordinated wing beating moves air across the wet honey, drawing out water and heat. Ventilation of the hive eventually expels both excess water and heat into

9324-529: The liquid. In this method, the sensor is submerged in the fluid and is made to resonate at a specific frequency. As the surface of the sensor shears through the liquid, energy is lost due to its viscosity. This dissipated energy is then measured and converted into a viscosity reading. A higher viscosity causes a greater loss of energy. Extensional viscosity can be measured with various rheometers that apply extensional stress . Volume viscosity can be measured with an acoustic rheometer . Apparent viscosity

9435-431: The melting point than at elevated temperatures. Melting 20 kg (44 lb) of crystallized honey at 40 °C (104 °F) can take up to 24 hours, while 50 kg (110 lb) may take twice as long. These times can be cut nearly in half by heating at 50 °C (122 °F); however, many of the minor substances in honey can be affected greatly by heating, changing the flavor, aroma, or other properties, so heating

9546-493: The middle of their life cycles they alternate between feeding on protein-rich pollen and feeding on honey, which is a far denser source of food energy . Human beings have semi-domesticated several species of honey bee by taking advantage of their swarming stage. Swarming is the means by which new colonies are established when there is no longer space for expansion in the colony's present hive. The old queen lays eggs that will develop into new queens and then leads as many as half

9657-559: The mixture of VOCs in different honeys in one review, longan honey had a higher amount of volatiles (48 VOCs), while sunflower honey had the lowest number of volatiles (8 VOCs). VOCs are primarily introduced into the honey from the nectar, where they are excreted by the flowers imparting individual scents. The specific types and concentrations of certain VOCs can be used to determine the type of flora used to produce monofloral honeys. The specific geography, soil composition and acidity used to grow

9768-435: The most relevant processes in continuum mechanics is not a coincidence: these are among the few physical quantities that are conserved at the microscopic level in interparticle collisions. Thus, rather than being dictated by the fast and complex microscopic interaction timescale, their dynamics occurs on macroscopic timescales, as described by the various equations of transport theory and hydrodynamics. Newton's law of viscosity

9879-400: The nectar once it is in the bee's honey stomach. These substances begin cleaving complex sugars like sucrose and starches into simpler sugars such as glucose and fructose . This process slightly raises the water content and the acidity of the partially digested nectar. Once filled, the forager bees return to the hive. There they regurgitate and transfer nectar to hive bees. Once it

9990-401: The outside world. The process of evaporating continues until the honey reaches its final water content of between 15.5% to 18%. This concentrates the sugars far beyond the saturation point of water, which is to say there is far more sugar dissolved in what little water remains in honey than ever could be dissolved in an equivalent volume of water. Honey, even at hive temperatures, is therefore

10101-521: The packaging and processing used. Regional honeys are also identified. In the US, honey is also graded on its color and optical density by USDA standards, graded on the Pfund scale, which ranges from 0 for "water white" honey to more than 114 for "dark amber" honey. Viscosity Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when

10212-452: The pots made of wax and resin used by the stingless bee . Honey for human consumption is collected from wild bee colonies, or from the hives of domesticated bees. The honey produced by honey bees is the most familiar to humans, thanks to its worldwide commercial production and availability. The husbandry of bees is known as beekeeping or apiculture, with the cultivation of stingless bees usually referred to as meliponiculture . Honey

10323-430: The processed nectar to bubbling and then passing the refined liquid on to others. It can take as long as 20 minutes of continuous regurgitation, digestion and evaporation until the product reaches storage quality. The new honey is then placed in honeycomb cells, which are left uncapped. This honey still has a very high water content, up to 70%, depending on the concentration of nectar gathered. At this stage of its refinement

10434-515: The relative velocity of different fluid particles. As such, the viscous stresses must depend on spatial gradients of the flow velocity. If the velocity gradients are small, then to a first approximation the viscous stresses depend only on the first derivatives of the velocity. (For Newtonian fluids, this is also a linear dependence.) In Cartesian coordinates, the general relationship can then be written as where μ i j k ℓ {\displaystyle \mu _{ijk\ell }}

10545-436: The strength of the compensating force is proportional to the fluid's viscosity. In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties is negligible in certain cases. For example, the viscosity of a Newtonian fluid does not vary significantly with the rate of deformation. Zero viscosity (no resistance to shear stress )

10656-509: The sugar source. Bee colonies that forage on Kudzu ( Pueraria montana var. lobata ) flowers, for example, produce honey that varies in color from red to purple. Honey has the ability to absorb moisture directly from the air, a phenomenon called hygroscopy . The amount of water the honey absorbs is dependent on the relative humidity of the air. Because honey contains yeast, this hygroscopic nature requires that honey be stored in sealed containers to prevent fermentation, which usually begins if

10767-440: The swarm will readily form a new colony in artificial surroundings. These semi-domesticated colonies are then looked after by humans practicing apiculture or meliponiculture. Captured bees are encouraged to forage, often in agricultural settings such as orchards, where pollinators are highly valued. The honey, pollen , wax and resins the bees produce are all harvested by humans for a variety of uses. The term "semi-domesticated"

10878-555: The term fugitive elasticity for fluid viscosity. However, many liquids (including water) will briefly react like elastic solids when subjected to sudden stress. Conversely, many "solids" (even granite ) will flow like liquids, albeit very slowly, even under arbitrarily small stress. Such materials are best described as viscoelastic —that is, possessing both elasticity (reaction to deformation) and viscosity (reaction to rate of deformation). Viscoelastic solids may exhibit both shear viscosity and bulk viscosity. The extensional viscosity

10989-715: The term containing κ {\displaystyle \kappa } drops out. Moreover, κ {\displaystyle \kappa } is often assumed to be negligible for gases since it is 0 {\displaystyle 0} in a monatomic ideal gas . One situation in which κ {\displaystyle \kappa } can be important is the calculation of energy loss in sound and shock waves , described by Stokes' law of sound attenuation , since these phenomena involve rapid expansions and compressions. The defining equations for viscosity are not fundamental laws of nature, so their usefulness, as well as methods for measuring or calculating

11100-485: The thorny-headed worms or spiny-headed worms, are characterized by the presence of an eversible proboscis, armed with spines, which they use to pierce and hold the gut wall of their host. The mouth parts of Lepidoptera ( butterflies and moths ) mainly consist of the sucking kind; this part is known as the proboscis or 'haustellum'. The proboscis consists of two tubes held together by hooks and separable for cleaning. The proboscis contains muscles for operating. Each tube

11211-583: The top plate moving at constant speed. In many fluids, the flow velocity is observed to vary linearly from zero at the bottom to u {\displaystyle u} at the top. Moreover, the magnitude of the force, F {\displaystyle F} , acting on the top plate is found to be proportional to the speed u {\displaystyle u} and the area A {\displaystyle A} of each plate, and inversely proportional to their separation y {\displaystyle y} : The proportionality factor

11322-507: The two systems differ only in how force and mass are defined. In the BG system the pound is a basic unit from which the unit of mass (the slug ) is defined by Newton's Second Law , whereas in the EE system the units of force and mass (the pound-force and pound-mass respectively) are defined independently through the Second Law using the proportionality constant g c . Kinematic viscosity has units of square feet per second (ft /s) in both

11433-425: The type of flora used to produce it (pasturage), temperature, and the proportion of the specific sugars it contains. Fresh honey is a supersaturated liquid, containing more sugar than the water can typically dissolve at ambient temperatures. At room temperature, honey is a supercooled liquid, in which the glucose precipitates into solid granules. This forms a semisolid solution of precipitated glucose crystals in

11544-450: The use of pollen as complementary food in Heliconius butterflies. An extremely long proboscis appears within different groups of flower-visiting insects, but is relatively rare. Some evolutionary lineages of gastropods have evolved a proboscis. In gastropods, the proboscis is an elongation of the snout with the ability to retract inside the body; it can be used for feeding, sensing

11655-403: The viscosity depends only space- and time-dependent macroscopic fields (such as temperature and density) defining local equilibrium. Nevertheless, viscosity may still carry a non-negligible dependence on several system properties, such as temperature, pressure, and the amplitude and frequency of any external forcing. Therefore, precision measurements of viscosity are only defined with respect to

11766-571: The viscosity rank-2 tensor is isotropic reduces these 81 coefficients to three independent parameters α {\displaystyle \alpha } , β {\displaystyle \beta } , γ {\displaystyle \gamma } : and furthermore, it is assumed that no viscous forces may arise when the fluid is undergoing simple rigid-body rotation, thus β = γ {\displaystyle \beta =\gamma } , leaving only two independent parameters. The most usual decomposition

11877-500: The viscosity, must be established using separate means. A potential issue is that viscosity depends, in principle, on the full microscopic state of the fluid, which encompasses the positions and momenta of every particle in the system. Such highly detailed information is typically not available in realistic systems. However, under certain conditions most of this information can be shown to be negligible. In particular, for Newtonian fluids near equilibrium and far from boundaries (bulk state),

11988-499: The water content of the honey is high enough that ubiquitous yeast spores can reproduce in it, a process which, if left unchecked, would rapidly consume the new honey's sugars. To combat this, bees use an ability rare among insects: the endogenous generation of heat. Bees are among the few insects that can create large amounts of body heat. They use this ability to produce a constant ambient temperature in their hives. Hive temperatures are usually around 35 °C (95 °F) in

12099-604: The winter depends on the variety of bees and on the length and severity of local winters. Many animal species are attracted to wild or domestic sources of honey. Because of its composition and chemical properties, honey is suitable for long-term storage, and is easily assimilated even after long preservation. Honey, and objects immersed in honey, have been preserved for centuries. (However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.) The key to preservation

12210-509: The yeast with enough of an increase in the water percentage for growth. Honey that is to be stored at room temperature for long periods of time is often pasteurized , to kill any yeast, by heating it above 70 °C (158 °F). Like all sugar compounds, honey caramelizes if heated sufficiently, becoming darker in color, and eventually burns. However, honey contains fructose, which caramelizes at lower temperatures than glucose. The temperature at which caramelization begins varies, depending on

12321-486: Was 1.8   million tonnes , led by China with 26% of the world total (table). Other major producers were Turkey , Iran , Argentina , and Ukraine . Over its history as a food, the main uses of honey are in cooking, baking, desserts, as a spread on bread, as an addition to various beverages such as tea, and as a sweetener in some commercial beverages. Due to its energy density, honey is an important food for virtually all hunter-gatherer cultures in warm climates, with

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