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CONTAMINATION, PRESERVATION AND SPOILAGE OF SUGAR AND SUGAR PRODUCTS

DRASHTI AIYA ROLL NO. : 01 CONTAMINATION

1. SUCROSE The raw juice expressed from sugarcane may become high in microbial content unless processing is prompt. Source of microorganisms are usually from the sugarcane and soil contaminating it. Much contamination may come from debris or fine particles on the sides or joints of troughs at the plant. Activity of organisms continues from cutting of cane through extraction to clarification of the juice, a process which kills vegetative cells of bacteria. Bacterial spores are present from then on, through sedimentation, filtration, evaporation, crystallization, and centrifugation, but may be reduced in numbers by these processes, although spores of thermophiles may be added from the equipment. Bagging of the raw sugar also may add some micro organisms. During refining of the sugar, contamination may come from equipment, and organisms are added during bagging. Contaminating organisms include: slime producers, such as species of Leuconostoc and Bacillus; organisms from the genera Micrococcus, Flavobacterium, Alcaligenes, Xanthomonas, Pseudomonas, Erwinia, and Enterobacter; a variety of yeasts, chiefly in the genera Saccharomyces, Candida, and Pichia; and a few molds. Effects of microbial contamination: inversion of sucrose or destruction of sugar.

2. MAPLE SYRUP Source of contamination: Sap of the sugar maple in the vascular bundles is sterile or so but becomes contaminated from outside sources in the tapholes and by the spout, plastic tubings, and buckets or other collection vessels. If a period of unusual warmth occurs before the sap is collected, considerable growth of yeasts and bacteria may take place in the sap. Contaminating microorganisms: Microorganisms entering sap between its flow from the tree and being boiled and concentrated are mostly psychrotropic, Gram negative rods of Psuedomonas, Alcaligenes, and Flavobacterium, plus yeasts and molds. Prevention of contamination- Paraformaldehyde taphole pellets are inserted into the drilled hole to prevent microbial growth from blocking the flow. In sugar-bush locations that are exposed to unusual dust and air contamination, collection of sap by a series of plastic tubes results in lower contamination. Sap gathering tanks, usually mobile, should be sanitized regularly to prevent development of high numbers of bacteria in the sap. Bacterial counts in the sap are usually less than 10,000 per millilitre, but higher numbers can develop as a result of warmer temperatures near the end of the season and poor sanitation.

3. HONEY

Source of microorganisms in honey are the nectar of flowers and the honeybee. Yeasts have been shown to come from the nectar and from the intestinal content of the bee; bacteria also come from the latter source. Contaminating organisms: common isolates are usually acidophilic and glycolytic yeasts, which can damage the product. Honey rarely contains Staphylococci or Enteric bacteria. Honey has been found to contain lysozyme, an enzyme with a bacteriostatic as well as a lytic effect on most Gram positive bacteria. The use of antibiotics such as neomycin and streptomycin is widespread in beekeeping, and these antibiotics have been found in the honey obtained from treated larvae and bees. The traces of these antibiotics in the honey would, of course, have an effect on its microbial flora. Honey is one of the suspected food vehicles for the source of C. botulinum spores in the case of infant botulism.

4. CANDY Candies and confections can be divided into two categories for microbiological considerations: A. Cold processed - Molded chocolate and chocolate coatings for creamed centers fall into the first category. Temperatures during processing may only approach pasteurization temperature. B. Hot processed - Examples of this category include hard candy, jellies, fudge and caramels. Processing temperatures for these items vary, but they are all exposed to a more severe heat treatment than items in first category. Source of microorganisms: The candies receive most of their contamination from their ingredients, although some contamination may be added to unwrapped pieces by air, dust and handling. Effects of contamination: Candies are infrequently associated with food poisoning outbreaks, but chocolate candies may include cases of Salmonellosis. The problem can be due to cross contamination in plant between raw and roasted cocoa beans, with the raw beans or environmental isolates serving as the source of contamination.

SPOILAGE

The spoilage of sugars or concentrated solutions of sugars is limited to that caused by osmophilic or xerotolerant microorganisms. Certain yeasts, especially those of the genus Saccharomyces, and certain molds would be the principal spoilage flora. Some species of bacteria also have been suggested as possible spoilage problems, including species of Bacillus and Leuconostoc. As the sugar concentrations decrease, increasing kinds of organisms can grow. 1. SUCROSE During the manufacture of sugar, the original cane or beet juice becomes more and more purified toward sucrose and the concentration of sugar in solution becomes greater and greater until finally crystalline sugar is attained plus molasses that is high in sugar. The purer the product, the poorer it becomes as a culture medium for microorganisms; the more concentrated it gets, the fewer kinds of organisms can grow in it. 2. RAW JUICE The raw cane or beet juice is not high in sugar and contains good supply of accessory foods for microorganisms; it therefore is readily deteriorated by the numerous organisms if sufficient time is allowed. Until clarification, gum and slime may be formed, e.g., dextran by Leuconostoc mesenteroides or L. dexranicum, less commonly, by yeasts or molds. 3. SUGAR IN STORAGE Liquid sugar with sugar content as high as 67-72 brix will support the growth of yeasts (Saccharomyces, Candida, Rhodotorula) and molds which may enter from the air. Dilution by absorption of moisture at the surface may result in growth of microorganisms and hence deterioration of the product. This can be prevented by circulation of filtered sterile air across the top of the storage tank or exposure to UV lamps. 4. MOLASSES AND SYRUPS Microbial spoilage of molasses is not common, although it is difficult to sterilize by heat because of protective effect of the sugar. Canned molasses or syrup may be subject to spoilage by osmophilic yeasts that survive the heat process. Molasses or syrup exposed to air will mold, in time, on the surface, and this also may occur at the surface of a bottled or canned syrup if air is left there and contamination has taken place prior to sealing. Some kinds of molasses are acid enough to cause hydrogen swells upon long storage.

5. MAPLE SYRUP

Five chief types of spoilage are recognized: SR. NO .

SPOILAGE TYPE

CAUSATIVE AGENT

1.

Ropy or stringy sap

Enterobacteraerogenes, Leuconostocspp.

2.

Cloudy, sometimes greenish sap

Pseudomonas fluorescens, spp. of Flavobacterium

3.

Red sap ( due to pigments of red bacteria )

Micrococcusroseus, or yeast or yeast like fungi

4.

Sour sap (sour odour)

Any kind of bacteria or yeasts

5.

Alcaligenes &

Moldy sap Molds (Aspergillus spp. or Penicillium spp.) The syrup may sometimes become dark because of alkalinity produced by bacteria growing in the sap and inversion of sucrose. 6. HONEY Honey is variable in composition but must contain no more than 25% moisture. Because of its high sugar content (70-80%), mostly glucose and levulose, and its acidity ( pH3.2 to 4.2 ), the chief cause of its spoilage is osmophilic yeasts of species of Zygosaccharomyces, such as Z.mellis, richteri, or nussbaumeri, or Torula (Cryptococcus) mellis. Most molds do not grow well on honey, although species of Penicillium and Mucor have developed slowly. Most honey yeasts do not grow in the laboratory in sugar concentrations as high as those found in honey. Therefore, special theories for the initiation of growth of yeasts in honey have been advanced: A. Honey, being hygroscopic, becomes diluted at the surface, where yeasts begin to multiply and soon adapt to high sugar concentrations. B. Crystallization of glucose hydrate from honey leaves a lowered concentration of sugars in the solution. C. On long standing, yeasts gradually become adapted to the high sugar concentrations. The critical moisture content for the initiation of yeast growth has been placed at 21%. The fermentation process is usually slow, lasting for months, and the chief products are carbon dioxide, alcohol, and non-volatile acids which give an off-flavor to the honey. Darkening and crystallization usually accompany the fermentation.

7. CANDY

Most candies are not subject to microbial spoilage because of their comparatively high sugar and low moisture content. Exceptions are chocolates with soft centres of fondants or of inverted sugar, which, under certain conditions, burst or explode. Yeasts growing in these candies develop a gas pressure which may disrupt the entire candy or more often will push out some of the syrup or fondant through a weak spot in the chocolate coating. The defect is prevented by using a filling that will not support growth of gas formers and be coating the candy with a uniformly thick and strong layer of chocolate.

PRESERVATION

Sugars normally have water activity so low that microorganisms cannot grow. Only when water has been absorbed is there a chance for microbial spoilage. Storage conditions must be such that vermin are kept out and the sugar remains dry. Cane or sugar beets may be store in a controlled atmosphere. Fungal growth is inhibited by 6% CO2 and 5% O2. Raw sugar- During the manufacture of raw sugar and subsequent refining process the number of microorganisms present, which may have been large during extraction from cane or beet sugar, are reduced by most subsequent processes, e.g. clarification, evaporation, crystallization, centrifugation, and filtration. Chemical preservatives are effective in reducing, microbial numbers during sugar refining. Care is taken to avoid buildup of organisms and their spores during processing, and the numbers may be reduced by irradiation with ultraviolet rays or combined action of heat and hydrogen peroxide. Candies- Because of their high sugar concentration and low water activity, most candies are not subject to microbial spoilage, although soft fillings of chocolate-covered candies may support the growth of microorganisms. The bursting of chocolates is prevented by a uniform and fairly heavy chocolate coating and use of fondant or other fillings that will not permit the growth of gas formers. Syrups and molasses- These usually have undergone enough heating to destroy most microorganisms but should be stored at cool temperatures to prevent or slow chemical changes and microbial growth. Some molasses may contain enough sulphur dioxide to inhibit microorganisms, but most of them contain no added preservatives and prevent microbial growth because of high osmotic pressure of sugar solution. The osmotic pressure increases with the extent of inversion of sucrose. Mold growth on the surface is prevented by a complete fill of the container and is reduced by periodic mixing of the syrup or molasses. Maple sap and syrup- The boiling process during evaporation of maple sap to maple syrup kills the important spoilage organisms. Such syrup, bottled hot and in a completely filled container, usually keeps well. Honey- Commercially distributed honey is pasteurized at 71°C to 77°C for a few minutes. A recommended treatment is to heat fairly rapidly to at least 71°C, hold for 5 minutes, and cool promptly to 32.2 to 38°C.

RECENT STUDIES

Penicillin and Tetracycline as Contamination Control Agents in Alcoholic Fermentation of Sugar Cane Molasses Experiments were carried out in an attempt to determine the influence of penicillin and tetracycline as contamination inhibitors in the alcoholic fermentation of molasses. Penicillin is a good contamination control agent in fermentation of molasses.Highly contaminated mashes can be recuperated by seeding-back with mashes containing penicillin. This antibiotic does not directly influence the yeast activity even when present in a concentration of 500,000 units per L. Tetracycline does not influence the fermentation time. This antibiotic acts as a contamination inhibitor when present in concentrations from 1 to 30 mg per L. (Aquarone, 1959)

Lead, cadmium and nickel in chocolates and candies from suburban areas of Mumbai, India Nickel, lead and cadmium contents were determined in 69 different brands of chocolates and candies available in local markets of suburban areas of Mumbai, India. Cocoa-based chocolates are found to have higher contents of the analysed heavy metals than milk-based chocolates, fruit flavour- or sugar-based candies. (Dahiya S. et al, 2005)

REFERENCES 1. Aquarone E., 1959, Penicillin and Tetracycline as Contamination Control Agents in Alcoholic Fermentation of Sugar Cane Molasses' Departnment of Chemiiistry, Escola Politenica, University of Sao Paulo, Sao Paulo, Brazil

2. Dahiya S., Karpe R., Hegde A., Sharma R., 2005, Lead, cadmium and nickel in chocolates and candies from suburban areas of Mumbai, India, Journal of food composition and analysis, Environmental Studies Section, Health Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India, Volume 18, issue 6

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