CONTAMINATION, SPOILAGE & PRESERVATION

SUGAR & SUGAR PRODUCTS

CONTAMINATION

• Latin word contaminat = “made impure.”

• Contaminate = pollute

• Contaminate something = impure or hazardous. 

SPOILAGE

• The action or process of spoiling of perishable goods.

• Spoiled food = damaged/ injured food undesirable for human consumption

• Food spoilage causes:-Physical injuryEnzyme activityMicrobes

PRESERVATION

• The action of preserving something.

• Food preservation – action of preserving food in order to maintain it as desirable for human consumption.

CONTAMINATION

Sucrose Maple sugar

• Honey

Candy Honey

SUCROSE

Contaminating sources

• Sugarcane • Soil• Handlers• Transportation• Air• Debris/ fine particles on the sides/ joints of

troughs at the plant• Industrial equipments & machines

Contaminants • Slime producers, like species of Leuconostoc

and Bacillus; representatives of the genera Micrococcus, Flavobacterium, Alcaligenes, Xanthomonas, Pseudomonas, Erwinia, & Enterobacter.

• A variety of yeast, chiefly in the genera Saccharomyces, Candida, & Pichia.

• A few moulds.

Stages when organism gets added

• Bagging of raw sugar

• Sugar refining

• From equipment

• From flume & diffusion battery waste

Microbial action

Cutting of cane

Extraction

Clarification

Result

• Sucrose inversion

• Sugar destruction

MAPLE SUGAR

Contaminating sources

Tree

Collection bucket

Handlers

Instruments

Air

Plastic tubings

spouts

Contaminants • Enter between its flow & being boiled &

concentrated• A moderate amount of growth - improve flavor

and color • The sap often stands under conditions that favor

excessive growth of micro organisms and hence spoilage.

• Mostly psychrotrophic, G - rods + yeasts + molds• Bacterial count - <10,000/ml

Prevention of contamination

• Paraformaldehyde taphole pellet

• Plastic tubing

HONEY

Contaminats

Yeast Bacteria

Bee(intestine) Nectar

Contaminats• Streptococci/ enteric bacteria – rare

• Common isolates – lysosome +

• Antibiotics- streptomycin, neomycin

• C. botulinum – infant botulism

• Gluconobacter & Lactobacillus – present during maturation of nectar to honey

CANDY

Contaminating sources

MICROBIAL LOAD – 0-2 MILLION BACTERIA/ PIECE

Classification of candies & confectionaries• Cold processed • Hot processed

Result of contamination

• Food poisoning outbreaks

• Salmonellosis

SPOILAGE• Osmophilic/ xerotolerant microbes

• Principle spoilage flora : Saccharomyces spp. & certain moulds.

• Bacterial spoilers – Bacillus spp. & Leuconostoc spp.

• Sugar concentration ∞ 1/micrbial load

SUCROSE

• At each processing stage it get more n more purified

• Sugar concentration increases – crystallization – sugar crystals + molasses

• Purity ∞ 1/micrbial load

Raw sugar cane juice• Low sugar content

• Good source of accessory foods for microbes

• Readily deteriorates

• Spoilages until clarificationGum/ slime : L. mesenteroids/ L.dextranicumLevan : Bacillus spp. (mostly); yeasts/ molds(rarely)

Sugar in storage• Liquid sugar :-i. 67 – 72 brix sugarii. support yeast’s growth (Saccharomyces,

Candida & Rhodotorula) & molds from air.

• Absorption of atmospheric moisture at surface – microbial growth – product deterioration.

Preservation : circulation of filtered sterile air

Molasses & syrups

• Microbial spoilage – not common

• Tough to heat sterilize

• Canned one’s : spoiler’s osmophilic yeasts

• Exposure to air – air left in containers –

spoilage before sealing

• Acidic one’s – hydrogen swells on storage

SL.NO.

SPOILAGE TYPE CAUSATIVE AGENT

1 Ropy or stingy sap Enterobacter aerogenes (mostly), Leuconostoc (responsible)

2 Cloudy, sometimes greenish sap P. fluorescens + Alcaligenes spp. + Flavobacterium spp.

3 Red sap Colored by pigments of red bacteria, e.g. Micrococcus roseus, /of yeasts / yeast like fungi,

4 Sour sap (a group o spoilages without marked color change but have a sour odor)

Variety kinds of bacteria or yeasts

5 Moldy sap Molds

Honey

• ≤ 25% moisture• 70 – 80 % sugar• Sugars : glucose(mostly) & levulose• Ph : 3.2 – 4.2• Chief spoilers : Zygosaccharomyces, such as

Z. mellis, richteri, or nussbaumeri, or Torula (Cryptococcus) mellis.

• Penicillium spp. and Mucor spp. have develop slowly.

Special theories for initiation of growth of yeast/ causes of spoilage of honey

• Honey- hygroscopic- surface dilution- yeasts multiplication & adaptation to high sugar concentrations.

• Crystallization of glucose hydrate from honey- lowers sugar concentration in solution

• Long standing- yeast’s gradual adaption to high sugar concentrations.

Factors effecting microbial growth in honey

• Critical moisture content of yeast – 21%

• Degree of sucrose inversion to by bees

• Available N content

Honey fermentaion

• Slow, lasts for months

• Chief products : CO2, alcohol, & non-volatile acids (give off-flavor)

• Usually accompanied by darkening & crystallization

Candy • Not subject to microbial spoilage - high sugar

& low moisture content.• Exceptions - soft fondant/ inverted sugar

centered chocolate- burst or explode.• Yeast growth develops a gas pressure - disrupt

the entire candy/ push out some of sirup or fondant through a weak spot in chocolate coating.

• Often this weak spot is on the poorly covered bottom of the chocolate coating.

PRESERVATION

• Storage conditions: keep out vermin -the sugar remains dry.

• Can or sugar beet - stored in a controlled atmosphere.

• Fungal growth inhibition by 6% CO2 & 5% O2.• During sugar manufacturing the refining processes

reduce microbial load present

• Chemical preservatives used in sugar refining.

• Care to avoid buildup of organisms and their spores during processing.

• Numbers may be reduced by irradiation with UV/ heat + H2O2

• Chocolate bursting - prevented by a uniform, thick chocolate coating & use of fondant/ other filling.

•

• Sirups and molasses - stored at cool T.• The boiling process (evaporation of maple sap

to maple sirup) kills the important spoilage organisms.

• Honey crystallization: heat to at least 71 C, hold there for 5 minutes, and cool promptly to 32.2 to 38 C.

• Molasses & sirups : high osmotic P (∞ degree of sucrose inversion). Mold growth prevented by complete filling of container & reduced by their periodic mixing.

REFERENCES

• Dennis C. Westhoff, William C. Frazier – Food Microbiology – fourth edition - The McGraw Hill companies – NewDelhi- pg.no. : 187 – 195.

• James M. Jay– Modern Food Microbiology –third edition – AVI book publications– usa- pg.no. : 193, 244-245

HIMA HARIDASAN