commercial yogurt production process pdf

Introduction to Yogurt 2. Preferably the culture should be transferred daily. In some countries the product made from these concentrated milk preparations is called “Bulgarian yogurt” to distinguish it from the “milk yogurt” prepared from un-concentrated milk. Share Your Word File Undesired bitter flavours in yogurt sometimes result from the use of poor quality milk or contaminated starter culture.

What are the general characters of pteridophytes? It has been further shown that Streptococcus thermophilus grown in association with Lactobacillus bulgaricus produces considerably more acid per cell than does the same culture when grown alone.

Why is the anterior pituitary considered to be a true endocrine gland, whereas the posterior pituitary is not? Under the conditions described here an active microbial culture requires only 2.5 to 3.5 hours to produce the desired amount of acid. Gorner et al. Yogurt starter cultures should be carried in sterile skim or whole milk. Welcome to BiologyDiscussion! Defects. It has been shown that the bacilli stimulate growth of Streptococcus thermophilus by releasing essential amino acids, especially valine, from the milk proteins. instead of being disposed [1]. nutrients developed during the fermentation process. Streptococcus thermophilus is considered to improve the body of yogurt by reducing the viscosity characteristic of milk cultures of Lactobacillus bulgaricus. The milk, having been thermised and cooled and containing the adequate fat content, has its solids standardised in a mixing line in which powdered milk along with other necessary dairy ingredients and required additives are added. When the mixture of yogurt microorganisms is inoculated into milk, the streptococci grow much more fastly than do the lactobacilli, often outnumbering the latter by 3 or 4 to 1 at the end of the first hour of incubation at 45°C (113°F). Addition of a small amount of rennet also increases firmness, but it harms the flavour and texture of the yogurt. Yogurt manufacture was initially based on knowledge and empirical processes without standard procedures or investigation of the steps that occur during the entire process. The yogurt is cooled to about 5°C (41°F) and held at this temperature until distributed to the consumer. Share Your PDF File Yogurt is made with a variety of ingredients including milk, proteins, fats, sugars, stabilizers, emulsifiers, fruits, flavors and bacterial cultures Yogurt is going through a rapid period of change with new raw materials being marketed with superpowers such as the ability to kill yeasts and moulds. Slow acid formation by yogurt cultures has been traced to bacteriophage-attack to the cells of Streptococcus thermophilus. What is seed dormancy? What are the modifications that are observed in birds that help them fly? Good quality milk is heated to reduce its microbial content as well as to improve it generally for growth of the yogurt microorganisms. Other workers, on the other hand, attribute all of the yogurt aroma and most of the flavour development to lactobacilli. Acid production during the latter part of the incubation period is accomplished by Lactobacillus. What is the reserve food material in red algae? Traditionally, yogurt was prepared from milk boiled for a considerable period of time to evaporate off part of the water and thus concentrate the solids. Whatever its specific role may be, Streptococcus thermophilus is necessary for production of good quality yogurt. Typical yogurt manufacturing entails the following: 1. Privacy Policy3. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Sausage Fermentation: Process, Production and Commercial Cultures | Industrial Microbiology, Classification of Milk: 3 Types | Milk Microbiology, Contamination of Milk by Microorganisms | Milk Microbiology. Assuming that the starter culture contains the desired balance of streptococci and lactobacilli, insufficient flavour development in the final product usually results from inadequate acid formation. (1968) reported that acetaldehyde production in yogurt takes place predominantly in the first 1-2 hr of incubation. Bulk starter culture is prepared in the same way, using larger quantities of milk. non-commercial research and educ ational use ... and process on yogurt texture: a review. Weak curd formation is a serious problem with yogurt made from milk of normal solids content.

For best results these microorganisms should be in approximately equal numbers in the culture; otherwise the yogurt will lack the most desirable consistency, flavour, and odor. Yogurt normally has a heavy consistency and resembles to custard.

C, fortified with 3% (w/v) nonfat dry milk, Although phage-resistant cultures have been developed, but the body of yogurt produced with these cultures is not as firm as is desired. Microorganisms in Yogurt and their Specific Role 4. Answer Now and help others. Disclaimer Copyright, Share Your Knowledge

Biology, Microbiology, Milk Microbiology, Yogurt. To achieve this range of acidity many producers remove the yogurt from the incubator when the acidity reaches 0.65 to 0.70 per cent.

Content Guidelines 2. Name the types of nitrogenous bases present in the RNA. 1. Good quality milk is heated to reduce its microbial content as well as to improve it generally for growth of the yogurt microorganisms. Control yoghurt and bio-yoghurts were manufactured using five commercial starter cultures. Firmness of the curd from “weak curd” milks can be increased by adding 1 to 2 per cent of dry milk solids or by homogenizing the milk at about 54°C (129.2°F) and a pressure of 3,000 pounds per square inch just before inoculation. Manufacture of Experimental Bio-Yoghurt. TOS4. The inoculum is mixed well with the milk, the mixture is dispensed in the final retail containers, usually jars or cartons, and these are incubated at 45°C (113°F). Streptococcus thermophilus and Lactobacillus bulgaricus are the microorganisms essential for yogurt preparation. 3. In addition to being acid, yogurt is said to have a mildly nut-like flavour and a typical “yogurt” aroma. Sample code, the microorganisms used in commercial starter cultures and incubation conditions were described in Table I. Why does plant cell possess large sized vacuole? Commercial Production of Yogurt 3. Also, some cows give milk that inherently forms a weak curd.

In this article we will discuss about:- 1. But most commercial yogurt starter cultures are supplied as mixtures of the desired microorganisms. The final acidity desired in the yogurt depends on the tastes of the consumer, but most seem to prefer a product with a titratable acidity of 0.85 to 0.90 per cent. The production of flavor by yogurt cultures is a function of time as well as the sugar content of yogurt mix. Gradually, the lactobacilli increase in numbers until at the end of the incubation period they again approximate the streptococci in numbers. What are the general characters of bryophytes? Absence of typical yogurt flavour and aroma also can result from use of such strains of Lactobacillus bulgaricus which produce little of the flavour and aroma substances. Attempts to popularize yogurt in the United States and Canada were first successful in the 1940’s. Optimum flavour development takes place only after the acidity reaches about 0.85 per cent, but ripening much beyond 0.95 per cent yields a product that is too sour. The separate pure cultures can be obtained either from stock culture collections or by isolating them from a good yogurt culture. The culture of lactobacilli produces enough acid to give the product its desired final characteristics and in addition releases the volatile products responsible for the typical yogurt flavour and aroma. Ideally the curd is smooth and firm. It is similar to fermented milks called “leben” in Egypt, “lebeny” in Syria, “dadhi” in India, and “mazun” in Armenia. Under these conditions the product can be kept satisfactorily for 1 to 2 weeks. Further acid formation takes place while the product is being cooled. Yogurt is one of the oldest fermented milk-product and has been an important food item of peoples in the Middle East since early times, especially in those countries bordering the eastern Mediterranean coast. Thus the initial acid production is due largely to the activity of Streptococcus thermophilus. Distributors of these cultures usually advise Yogurt producers to obtain new starter cultures each week or two, rather than attempt to carry the cultures in the dairy plant and run the risk of changes in the characteristics of the starter culture.

Hello world!

Click to share thisClick to share this