4 - Food Fermentations

4 - Food Fermentations - Food Fermentations Jan 18 Jan 20,...

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Food Fermentations Jan 18 – Jan 20, 2010 Food preservation using fermentation What is fermentation? Involves the conversions of food components into a more stable form through the use of microorganisms Produces amino acids, acids, alcohols, other small organic compounds and gases o Use of yeast, bacteria, mold, etc Results of fermentation? Will generally reduce the likelihood of foodborne pathogens growing in the food o Related to acid production o Can also extend shelf-life of product o Related to inhibition of spoilage organisms due to acid or alcohol production Will produce a new food product from raw materials: o Grapes -->> yeast -->> wine o Milk -->> mold -->> Camembert cheese o Cabbage -->> bacteria -->> sauerkraut or kimchi o Wheat -->> yeast-->> bread Types of fermentations: I. Natural or “wild” fermentations Microorganisms of interest is naturally present on starting material food: o Ex. sauerkraut, pickles, olives II. Controlled or “inoculated” fermentations An innoculum or “starter culture” is added to the starting food material, using a dose of the microorganism of interest o Ex. cheese, yogurt, beer, wine, vinegar, bread, sausage From a commercial perspective, you want the product to be consistent, and therefore, wild micro flora isn’t reliable (use of controlled fermentation is preferred in industrial settings) Bacterial fermentations Lactic acid bacteria: Most important bacteria in desirable fermentations Gram positive cocci or bacilli Microaerophillic (little bit of O 2 ) Non-sporeformers Lactic acid id a major metabolic end-product o Responsible for pH change, flavour changes, sourness change Homofermentative : C 6 H 12 O 6 2 CH 3 CHOHCOOH o Lactic acid is the main product o Conversion to TWO molecules of lactic acid Heterofermentative : C 6 H 12 O 6 2 CH 3 CHOHCOOH + C 2 H 5 OH + CO 2 + CO 3 COOH o Lactic acid isn’t the only product; products vary o ~50% of product is lactic acid, 25% product is CO 2 , 25% product potentially ethanol or acetic acid Lactobacillus spp. o Heterofermentative = intermediate acid level in product moderate pH change from original product o Homofermenatative = most acid level in product bigger pH change from original product Leuconostoc spp. o Heterofermentative = intermediate acid level in product moderate pH change from original product Pediococcus spp. o Heterofermentative = intermediate acid level in product moderate pH change from original product Streptococcus spp o Heterofermentative = intermediate acid level in product moderate pH change from original product Leuconostoc mesenteroides o Sauerkraut and pickle production
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This note was uploaded on 12/26/2011 for the course FND 100 taught by Professor Y.yuan during the Winter '10 term at Ryerson.

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4 - Food Fermentations - Food Fermentations Jan 18 Jan 20,...

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