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Similar to fermented milk_ different products .pptx
fermented milk_ different products .pptx
- 2. Milk • precise componentsof raw milk vary by species and by a number of other factors, but it contains significant amounts of saturated fat, protein and calcium as well as vitamin C • Cow's milk has a pH ranging from 6.4 to 6.8, making it slightly acidic • gross composition of cow's milk in the U.S. is 87.7% water, 4.9% lactose (carbohydrate), 3.4% fat, 3.3% protein, and 0.7% minerals (referred to as ash) • Milk composition varies depending on the species (cow, goat, sheep), breed (Holstein, Jersey), the animal's feed, and the stage of lactation
- 3. Milk • Water –87% (lactose, glucose) • Protein – 3.5% (casein) • Fat – 3.9% • Carbohydrate – 4.9% • Ash – 0.7% (calcium, iron) • Vit B, pantothenic acid, riboflavin • pH of fresh milk is 6.6 • If pH falls below 4.6, casein ppts • Liquid – whey
- 4. Processing • Cream • Cheese •Butter • Whole fresh milk – Skim milk (0.5% fat) • Produced by high speed centrifugation following heating to 100°F to remove butter fat and cream • Pasteurized (65.5-68.3°C)and cooled to 4C
- 5. • Evaporated milk– removal of 60% water • Sweetened condensed milk – addition of glucose or sucrose before evaporation • Sugar content of 54% - 64% • Chocolate milk • Fermented milks
- 6. Pasteurization • Objective isdestruction of all disease causing microorganisms by heating • Endospores of C. botulinum, B. cereus not destroyed • LTLT – low temp long time- 63C for 30min - Done by batch method • HTST – high temp short time – 72C for 15s - Done by flash method • UHT – ultra high temperature • 135- 140 C for few seconds - Commercially sterile - Thermodurics – Enterococcus, Streotococcus, Microbacterium, Lactobacillus, Mycobacterium, Corynebacterium and sporeformers survive
- 7. Fermented products • Startercultures • Added to modify aroma and texture • LAB are commonly used but not the only starters • Some starters will produce acid • Propionibacterium shermanii in swiss cheese • Some starters will coagulate proteins • – Thickening of yogurt by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus • Some starters will produce a specific aroma • Penicillium roquefortii in roquefort cheese
- 8. Fermented products • Cheeses •Fresh or unripened • Cottage, Cream, Mozzarella, Neufchatel, several Mexican-style cheeses • Ripened • Soft surface ripened • Camembert, Brie • Semisoft • Muenster, Gouda, Edam, Roquefort, Blue • Hard • Cheddar, Swiss, Ementaler, Gruyere • Hard-grating • Romano, Parmesan
- 9. Fermented products -spoilage • Cheeses • Microbial spoilage limited by combined effect of salt, acid and bacterial activity • Some cheeses may permit growth of anaerobic sporeformers, causing gassy spoilage • Fresh cheeses have a pH >5.0 and aw >0.9 • therefore may be spoiled by Gram-negative psychrotrophic bacteria • Pseudomonas, Flavobacterium, Alcaligenes
- 10. Fermented Milks • Mesophilicmilk fermentations • acid produced through microbial activity-protein denaturation • inoculate milk with the desired starter culture ; optimum temperature (approximately 20 to 30°C), and • then stops microbial growth by cooling • Lactobacillus spp. ,Lactococcus lactis - aroma and acid production. • The organism Lactococcus lactis subsp. diacetilactis converts • milk citrate to diacetyl- buttery flavor • skim milk produces cultured buttermilk, • when cream is used -sour cream
- 11. • Buttermilk- Pasteurisedlow fat/skim milk • Streptococcus lactis- • 20-22 degree cel • Till 0.8-0.9 % acidity, pH 4.6
- 14. • Thermophilic- attemperatures around 43- 45°C. • Yogurt -starter culture - 1:1 ratio: S. thermophilus and L. bulgaricus.
- 15. yogurt • Homogenized milk(12% TS) + stabilizer (l %).- give desired gel structure. • Heated to 185°F (85°C) for 30 min. -cooled to llOoF (43.3°C) • helps destroy vegetative microbes and slightly destabilize casein for good gel formation. • Starter added, incubated at (43.3°C) to pH 4.8 for ca. 6 h, acidity ca. 0.9%. • Quickly cooled to 85°F(~30C)in ca. 30 min to slow down further starter growth and acid production, especially by Lactobacillus species, agitated, and pumped to filler machine. • Packaged in containers, and cooled by forced air to 40°F (4.4°C). • Final cooling by forced air results in a rapid drop in temperature to stop the growth of starters. • Held for 24 h; pH drops to 4.3.
- 16.
- 17. probiotics • Microbes indiet- dietery adjunct-health benefits- control of diarrhea, inflammatory bowel disease, anticancer, immunomodulation ,Stabilize intestinal microflora • Acidophilus milk- Lactobacillus acidophilus- stabilize the bowel microflora, antimicrobial properties, minimizing lactose intolerance, lowering serum cholesterol, and possibly anticancer activity- colon cancer
- 18. Probiotics • Consumable productthat contains live organisms that are beneficial to consumers • Ingestion of live organisms – yogurt, fermented milk • Inhibitory effect for pathogens • pH reduction, bacteriocins, organic acid toxicity
- 19. Acidophilus milk • Inoculationof L. acidophilus into sterile skim milk • 1-2% , 37C • Smooth curd develops
- 20. Prebiotics • Not microorganismsbut they are substrates for indigenous probiotic- type bacteria that reside in the colon • Substrates are nondigestible as they pass through small intestine • Oligosaccharides – fructooligosaccharides eg. Inulin • Metabolized by bifidobacteria and anaerobic lactobacilli (colon) • Can be added to number of food types that do not support cell viability over long periods of time
- 21. Microscopic views ofstained bacteria Lactobacillus spp. Lactococcus spp.
- 23. • Bifidobacterium • nonsporing,gram-positive rods that may be club- shaped or forked at the end, nonmotile, anaerobic, and ferment lactose and other sugars to acetic and lactic acids. • They are typical residents of the human intestinal tract- maintain the normal intestinal balance, while improving lactose tolerance; to antitumorigenic activity; and to reduce serum cholesterol Levels, promote calcium absorption, synthesis of B- complex vitamins,reduce or prevent the excretion of rotaviruses, a cause of diarrhea among children
- 25. • Yeast-lactic fermentations-kefir, a product with an ethanol concentration of up to 2%. • foamy and frothy, due to active CO2 • fresh milk + Kefir “grains” - inoculum-coagulated lumps of casein that contain yeasts, lactic acid bacteria, and acetic acid bacteria • contain a water soluble polysaccharide known as kefiran, which imparts a rope-like texture and feeling in the mouth • Originally,- leather sacks hung by the front door during the day, and passersby were expected to push and knead the sack to mix and stimulate the fermentation.
- 28. Fermented Milk Products •Kumiss • traditionally made from mare's milk • produced from a liquid starter culture, in contrast to the solid kefir "grains“ • Because mare's milk contains more sugars than the cow's or goat's milk fermented into kefir, kumis has a higher, though still mild, alcohol content – 2%
- 29.
- 30. • Mold-lactic fermentation– viili • milk + a mixture of the fungus Geotrichium candidum and lactic acidbacteria • cream rises to the surface, and after incubation at 18 to 20°C for 24 hours, lactic acid reaches a concentration of0.9%. • The fungus forms a velvety layer across the top