Bottle way of receiving ferments of true cultures.

The ferment received from laboratory is brought in the prepared milk which is spilled in seven sterile bottles. Bottles with skvashenny milk store in the refrigerator. The next day from the first bottle prepare secondary culture. For the third day from the secondary culture which was in the first bottle prepare working ferment and on the same day from the second bottle prepare secondary culture. For the fourth day working ferment is received from secondary culture of the second bottle, and from the third bottle - secondary culture the next day. Act daily this way, receiving working ferment for the present day and preparing culture on following.

In all cases of emergence in ferments of defects (a flabby clot, foreign smack, the slowed-down folding) from laboratory culture prepare maternal and the subsequent ferments again.

The worker and parallel ferments is stored at 8-10 °C no more than two days. Through each 10-12 changes ferment is changed. Some feature is represented by kefiric fungi. Microflora of kefiric fungi consists of a symbiotic combination of lactic streptococci and sticks, the aromatobrazuyushchikh of bacteria, milk yeast, microtherms (filmy yeast) and acetic bacteria. Kefiric grains serve as maternal ferment from which the subsequent receive all for production of kefir. Technical progress of poseshas allowed to receive continuously fungal ferment and to create the automated product line on production of kefir. Advantage of this method is that favorable conditions for development of all components of microflora of kefiric ferment (lactic streptococci, sticks, yeast) are created.

Control questions:

1. What types of ferments you know?

2. Give the characteristic of working ferment?

3. Characterize a bottle way of receiving ferments.

Laboratory work №9

Studying of technological features of liquid fermented milk products.

Work purpose: To examine the main technological processes of production of liquid fermented milk products, to study influence of the technological modes on quality of a ready-made product.

Task:

1. To define influence of temperature of pasteurization of milk on quality of finished fermented milk product.

2. To define influence of temperature of souring on quality of finished fermented milk product.

3. To carry out assessment of quality of finished fermented milk products on the following indicators: organoleptic assessment; acidity; amount of the emitted serum.

Short theoretical data

Dietary fermented milk products of all types develop according to the general technological scheme. The prepared milk skvashivatsya by ferments of true cultures then the received clot is cooled and ripens. Distinctions by production of separate types of products can be in temperature conditions of preparation of milk, souring and maturing, and also in use of ferments of various structure and introduction of fillers.

Develop liquid fermented milk products in the thermostately and reservoir way according to the technological scheme (figure 1.1).

When carrying out process of normalization the mass share of fat of ferment which is contributed in milk is considered. A mass fraction of fat to which it is necessary to normalize milk, determine by a formula:

,

where Zhn.M. – a mass fraction of fat in the normalized mix, %;

Zhpr. – a mass fraction of fat in a ready-made product, %;

Кз – the mass of the brought ferment, %;

Жз – a mass fraction of fat in ferment, %.

When using ferment of direct introduction the mass fraction of fat of the normalized mix is equal a mass fraction of fat of a ready-made product. By production of fermented milk products with fillers the composition of mix is counted on compoundings.

To receive a quality product, with the dense clot which is well holding serum a certain thermal impact on proteins of milk as the main water connecting milk components is necessary. Such impact on proteins of milk is reached when heating him higher than 85 C and amplifies at his long endurance at these temperatures. Besides, for receiving a product with a dense uniform clot, it is necessary to maintain temperature of a zakvashivaniye, optimum for this type of a product, and souring.

Acceptance and preparation of raw material

Normalization

Cleaning

Pasteurization

Homogenization

Cooling up to the zakvashivaniye temperature

Souring

Tank method

Thermostately method

Souring

Pouring

Hashing

Souring

Cooling

Cooling

Maturing

(for kefir, koumiss)

Maturing

Pouring

Quality check

Storage

Realization

Figure 9.1 – Technological scheme of production of dairy drinks

 

Duration of souring of milk depends on a type of the developed product and fluctuates ranging from 4 till 20 o'clock. The end of souring is determined by acidity of a clot which has to be slightly lower, than in a ready-made product, and on character of a clot – he has to be gentle, moderately dense, without office of serum.

Equipment, devices and technical means:

Work performance order

1. To carry out assessment of quality of the prepared ferments (organoleptic assessment and acidity).

2. To receive milk, to carry out assessment of his quality.

3. To normalize milk to the set mass fraction of fat.

Definition of influence of temperature of pasteurization of milk on quality of finished fermented milk product.

The normalized mix is spilled in two flasks. Milk in the first flask will be pasteurized at a temperature and endurance according to the technological instruction for this type of a product. Milk in other flask will be pasteurized at a temperature at 10-15 °C below, without endurance. To carry out a zakvashivaniye and souring at an optimum temperature for this type of a product.To give an assessment of quality of a ready-made product.

It is necessary for definition of influence of temperature of souring on quality of finished fermented milk product - the normalized mix is spilled in two flasks. Milk in both flasks will be pasteurized at a temperature and endurance according to the technological instruction for this type of a product. Carry out a zakvashivaniye and souring of milk in the first flask at an optimum temperature for this type of a product, in the second flask at a temperature at 5-8 °C below optimum.

To carry out assessment of quality of finished fermented milk products on the following indicators:

- organoleptic assessment;

- acidity;

- a mass fraction of fat for fat-containing products;

- amount of the emitted serum.

It is necessary for determination of amount of the emitted serum a clot of fermented milk product carefully mix to a uniform state. The shattered clot is filled in in three centrifugal test tubes on 10 ml to a tag. Test tubes establish for 10 min. in a water bath at a temperature of 30-35 C then they centrifuge within 30 min. and define amount of the emitted serum. Take average value of three test tubes for final result.

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