Honey - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 125

table 5.2 honey Grading Scale

Grade Moisture taste Clarity Quality Defects

A <18.6% Very good Very clear Free of quality defects

B <18.6% Good Clear Fairly free of quality defects

C <20.0% Fairly good Fairly clear Some quality defects

Below
standard

>20.0% Not good Not clear Quality defects

Source: Modiied from Grout, R. A. The Hive and the Honey Bee, Revised Edition , Dadant and Sons, Hamilton, IL,
1992.

above criteria, as shown in Table 5.2, according to how the honey lows without breaking into
separatedrops.Honeywithlowwatercontentissuitableforlongpreservationbecauseofitsunique
compositionandphysical,biological,andchemicalproperties.
Excessive heat (37°C-50°C or 98°F-122°F) causes the loss of important antibacterial, nutri-
tional,andenzymaticcomponents.Ontheotherhand,crystallizationdoesnotaffectthenutritional
aspectsofthehoneyandisafunctionoffactorssuchastemperatureandotherspeciiccompounds
(sugarsandtraces)inthehoney.
Inmedicine,honeyhasbeenusedtotreatvariousailmentstohumansthroughitsantisepticand
antimicrobialproperties,whicharetheresultoflowwateractivity(causingosmosis),ahydrogen
peroxideeffect,highacid,andmethylglyoxal(MGO;anactiveantimicrobial).
Honeyisamixtureoftwoprimarilysaturatedmonosaccharides(fructoseandglucose).Itslow
wateractivityisassociatedwithcontainedsugars,andtherefore,fewwatermoleculesremainavail-
ableformicrobialgrowth.
Whenhoneyisappliedtoawound,hydrogenperoxideisreleasedbytheenzymeglucoseoxi-
dase(presentinhoney)bythedilutionofthehoneywithbodyluidsandactsasanantisepticagent.
Thisisdescribedinthefollowingequation,whichshowstheglucoseoxidasereaction:

C H O H O O + + → C H O H O +

(5.1)

6 12 6 2 2 6 12 7 2 2

Inaddition,therelativelylowacidicpHofhoney(3.2-4.5)preventsthegrowthofmanybac-
teria,yeast,andmolds(WaikatoHoneyResearchUnit2011).Theantibioticactivityofhoneyisa
result of MGO and a synergistic unknown component. In addition, honey has functional effects
throughitsantioxidantsimplicatedinreducingdamagesfromcolonproblems(diseasecolitis).

5.8 MICrOBIOLOGICaL aSpeCtS

Thequalityandsafetyofhoneyisinluencedbymicrobes,butofmostconcernarethefollow-
ing:(1)microbescommonlyformedpostharvest(yeastsandspore-formingbacteria);(2)microbes
thatindicatethecommercialqualityofhoney(coliformsandyeasts);and(3)microbesthatcause
humanillness(SnowdonandCliver1996).
Sourcesofhoney'smicrobialcontaminationarebothprimary(e.g.,pollen,digestivebeetracts,
andnectarairpollution)andsecondary(e.g.,air,handling,andequipment).Microbesoftenfound
invarioushoneysareprimarilyofconcern;theyareyeasts(fromverylowtoveryhighnumbers)
andspore-formingbacteria(usuallyoftheBacillusgenusandlessoftenoftheClostridiumgenus).
However,nosuchvegetativedisease-causedbacterialspecieshavebeenfoundbecauseoftheanti-
microbialpropertiesofhoneys.Severaltests,suchasstandardplatecount(SPC)andotherspecial-
ized tests (yeast and coliform counts), may be useful as an indicator of honey's sanitary quality
(WaikatoHoneyResearchUnit2011).