Preparation of yoghurt

Bulk yoghurt starter

Bulk starters are carried in stainless steel vessels or vats with sufficient capacity to contain 2 parts starter for every 100 parts of yoghurt made. The necessary quantity of skim milk is heated to 185 ° – 190 °F for 30 – 45 min, cooled to 110 °F and inoculated with 1% each of S. thermophilus and L. bulgaricus mother culture. The ratio of the two microorganisms in a starter or product has a marked effect on its flavor and odor. A ratio of 1 to 1 is usually preferred. Starters are mixed in the milk and it is incubated at 105 ° – 110 °F until coagulation occurs. Bulk starter is cooled to 50 °F and stored at 40 °F is not used promptly.

Firm-Bodied Type

Nonfat dry milk or skim milk concentrate is added to whole or partly defatted milk to increase the milk-solids-not-fat by 2 – 3% to a total of approximately 12%. The mix is warmed to 140 °F and homogenized, single-stage at 2000 – 2500 psi to disperse the fat. Stabilizers are frequently added to the mix but are not essential and excessive amounts are to be avoided. The mix is heated in the vat to 185 °F for 30 min and then cooled to 110 ⁰ – 112 °F, inoculated with 2% bulk starter and stirred briefly to mix. The incubation temperature of 108 ° – 110 ⁰F is held fairly constant and not allowed to fall much below 106°F during the filling operation. The time interval between inoculation and filling should not exceed 45 min. Yoghurt is incubated in package without further agitation at 106 ° – 108 °F for about 3 hr. Incubation is terminated when a titratable acidity of 0.75% is reached. The yoghurt is then placed under refrigeration to cool to 40 ° – 45° F; approximately 8 hr is required, at which time the product «ready for distribution. A final acidity of about 0.9% is desired in the product.

Viscous or Semiliquid Type

This type is partly or completely incubated in the vat. The preparation of mix ingredients is essentially the same as with firm-bodied yoghurt. Some manufacturers prefer a slower rate of acid development in the vat and therefore reduce the inoculum size to 1%. Incubation temperature may begin at 11Q °F and gradually cool down to 100 °F. After coagulation the yoghurt is chilled as quickly as possible to 50 °F, accompanied by slow and intermittent' stirring. Fruits and flavors may be carefully blended in the yoghurt at this time. The yoghurt is packaged and stored for 16 – 24 hr at 40 ⁰Fand marketed.

Flavored

The addition of flavors, fruits, and preserves to yoghurt has become very popular in recent years.

Flavors for yoghurt are of three types: the synthetic or artificial, natural with synthetics added, and the natural fruit purees. These flavors may be added to the yoghurt in 1 of 3 ways.

(1) By mix blending-the flavoring material, sugar, and color are added.to the mix prior to fermentation.

(2) Fruit on bottom-preserves or fruit are added to the package prior to filling and setting.

(3) Bulk mixing-yoghurt is prepared, bulk chilled, and mixed with a fruit dressing, and packaged. Fresh fruit, preserves, flavors, sugar, and color are blended in after fermentation.

Flavored yoghurt has a definite advantage over the plain yoghurt in that the harsh acidity in the product is less pronounced, the incidence of objectionable off-flavors is reduced, and much of the need for concentrating the milk is eliminated.

Задание 2.Найдите в тексте эквиваленты следующих словосочетаний:

встряхивать урывками; инкубационная температура; конечная кислотность; синтетические добавки; фруктовые пюре; объемное смешивание; йогурт с вкусовыми добавками; определенное преимущество; обычный йогурт; резкая кислотность.

Задание 3. Назовите глаголы, от которых были образованы данные существительные и переведите их на русский язык. Определите, какие суффиксы были использованы при словообразовании:

concentration; pasteurization; homogenization; development; stabilization; package; mixture; preparation; addition.

Задание 4. Сопоставьте английские слова с их переводом:

1) nonfat dry milk; 1) частично обезжиренное молоко;

2) firm-bodied yoghurt; 2) йогуртная закваска;

3) synthetics additions; 3) йогурт со вкусовыми добавками;

4) to chill quickly as possible; 4) синтетические добавки;

5) partly defatted milk; 5) йогурт плотной консистенции;

6) flavored yogurt; 6) обезжиренное сухое молоко;

7) yoghurt starter; 7) охладить как можно быстрее.

Задание 5. Дайте ответы на предлагаемые вопросы по тексту:

1. What kind is necessary for preparation yoghurt starter?

2. What influences on flavor and odor of yoghurt?

3. What mother culture is used in preparation of yoghurt starter?

4. How much time does the process of chilling firm-bodied yoghurt take?

5. Why are flavored yoghurts so popular now?

Вопросы к практическому заданию

1. Какие бывают виды йогуртов?

2. Как производится основная йогуртовая закваска?

3. Какие вкусовые добавки используются в производстве йогуртов?

Практическое занятие 14

КРИСТАЛЛИЗАЦИЯ ЛАКТОЗЫ В СЫВОРОТОЧНОМ ПЕРМЕАТЕ

LACTOSE CRYSTALLIZATION IN WHEY PERMEATE

Теоретическая часть

Данный лексический материал предназначен для того, чтобы студенты могли понимать специальные тексты на иностранном языке, необходимые им для работы в своей области, а также составить собственное высказывание по заданной теме.

ethanol leaching method метод выщелачивания этанолом

high purity lactose лактоза высокой чистоты

provided зд. при условии, что

highly supersaturated solution высокопересыщенный раствор

protein raffinate рафинированный белок

solid state твердое состояние

lactose monohydrate (LMH) моногидрат лактозы

approximately приблизительно

saturation point точка насыщения

in 62% methanol с 62% метанолом

was comparable to that of the была сравнима с теми же

refined milk sugar of commerse показателями для торгового