Spoilage of Cereal and Cereal Product /Bakery product

Cereal and cereal product / Bakery product

Contamination

Microorganism on the surface of grain come from two sources . One from external sources such as insects and other from the original flora of the grain . A Large number of bacteria and fungal spores are found on the surface of the grain . Bateria commonly found include Pseudomonas , Micrococcus ,Lactobacillus , and Bacillus. The milling process and washing remove a number of microorganism from the surface . Bacteria in flour include spore of Bacillus , Coliform bacteria few species of Achromobacter, Flavobacterium, Alkaligenes , Serratiaetc. spores of Penicillium and Aspergillus are also common in wheat flour. the surface of freshly baked bread is free of microorganism. They are subjected to contamination may also occur from other equipment like slicing knife .

Preservation

Asepsis : Sanitization of processing equipment for asepsis . Bread . cake and other bakery product may subject to spoilage by mold spores . Therefore, they should be protected against contamination by mold spores

Use of heat : Heat is applied during baking of bakery product . Complete baking kills most bacteria cells yeast and mold.

Use of low temperatures : In the home , bakery product are usually kept at room temperatures but the keeping of time of some bakery product

Use of chemical preservations :Insecticides antifungal agent , ammonia, and propionic acid are very effective in preventing mold growth and mycotoxin production in grains kept at moist conditions sodium and calcium propionate, sodium diacetate and sorbates are used as mold inhibitors in bread , rolls , cakes and other bakery products.

Use of irradiation :Low-level irradiation can be used to kill the insect in stored grain . Uv light is used to kill or reduce the number of mold spores in the dough and on the surface of baked bread and on slicing knives.

Spoilage

Cereal grain flour and their products are rich in carbohydrates but contain very low amount of moisture . Hence, they are rarely spoiled by the microorganism. However, it these products becomes moistened, the growth of microorganism will occur which result in spoilage. Microbial flour of harvested grain includes naturally as well as contamination from soil, insect , birds , and irrigation water . Usually, bacteria blends to family Bacillaceaceae , Lactobacillaceae , Enterobactraceae , Pseaudomonaceae found in freshly harvested stored grains . Microorganism in grain is removed or kill during procedures employed for flour making.

Cereals and grain : A wet mass of grain or meals will undergo lactic acid fermentation of lactic acid bacteria and coliform bacteria normally present on the surface of the grain . This may be followed by alcoholic fermentation by yeast as soon as acidity has increased enough to favor them . Finally, mold grows on the top surface . If acetic acid bacteria are present , they oxidize alcohol to CH3COOH and inhibit mold . Different types of molds are responsible for spoilage eg, Aspergillus , Penicillium , Mucor , Rhizopus, and Fusarium . Many types of mold produce Mycotoxin.

Flour : white flour is usually bleached by an oxidizing agent such as an oxide of nitrogen , chloride , nitrosyl chloride and benzoyl peroxide . This process server to reduce the number of microorganisms in flour.Low moisture content also discourages microbial growth . Type of spoilage is diffused to predict . Slight increase in moisture initiates molds growth . If acid forming bacteria are present acid fermentation begins followed by alcoholic fermentation by yeast finally acetic acid bacteria oxidize alcohol into acetic acid if they are present .

Dough and bread : Various type of fermentation by the microorganism is a common type of spoilage in dough . Some of the fermentation are desirable and are used for making some bread . If the dough holds for long time scouring occurs by acid fermentation of lactic acid and coliform bacteria . Excessive growth of proteolytic bacteria reduce gas holding capacity and result in sticky dough . The sticky dough also results by overmixing .

a common type of spoilage of bread include ;

• Moldiness :Cause by various species of mold . Moldiness of baked bread is encouraged by having contaminated after baking and storage in humid and warm environment Rhizopus stolonifer ( bread mold ) grow with colony Mycelium and black dots of sporangia Penicillium expanse give green colouration due to green spores . Similarly, Monilia ( Neurospora ) Sithophilagive red colouration due to red conidia Aspergillus niger give greenish or purple brown black clots of conidia and at the same time yellow pigment diffusing into the bread is also found .
• Ropiness : Caused by a mucoid variant of Bacillus subtilis or Bacillus lichen forms . Their spores can withstand the temperature of baking and german read in bread if the condition is favorable. Ropiness is due to the capsule of Bacillus together with hydrolysis of gluten protein and starch by enzymes of bacteria . Area of business is yellow to brown in color and is soft sticky to touch. The rope condition apparently is the result of encapsulation of Bacillus species together with hydrolysis of flour protein . By process, enzymes produce by the organism and off starch by formation . They are of ropiness in yellow to brown in color and soft sticky to touch sometimes a material can be drowned out into a long thread . When the bread is broken and pulled softness , stillness, and unpleasant order are the main characteristic ropiness of bread.
• Red bread :Red bloody bread is caused by red pigmented Serratia marcescence and molds such Monilia Sito Phila .
• Chalky bread :In this case , the spoiled area becomes whites chalky like it is caused by species of Endomycopsis and Trichosporum .

Cake and other bakery product :Molds are main caused by spoilage of cakes and other bakery product. Microorganism on this product become more complicated when they are filled with frostings . Sugary material cream or sauce . The fillings are more susceptible to microbial spoilage then baked portion of this product .

Pasta and Marconi :Pasta is a market and stored dry . Therefore , they usually are not spoiled by the microorganism . Swelling of moist macro- ni is caused by gas-producing bacteria such as Enterobacter cloacae.

Reference

Frazier, WC and Westhoff DC.Food Microbiology.3rd. New Delhi: Tata McGraw-Hill Publishing Company Limited, 1986.

Jay, MJ.Moderen Food Microbiology.Ed. India. 3rd. Delhi: CBS Publications and Distributions, 1987.