Сельское хозяйство/4.Технологии хранения и переработки сельскохозяйственной продукции

Piriev A.U., Ph.D. Gunkova P.I.

ITMO University, Saint Petersburg, Russia

Impact of bacterial preparations on quality and quantity of curds were made from milk with protein concentrate from dairy factories of Leningrad region

At present time in the world there is the problem of protein malnutrition in the nutrition of population. Protein malnutrition results in the disruption of the central nervous system, a reduction in physical and mental stamina and dysbacteriosis. Protein malnutrition affects appearance of man, for example, it results in impairment of the skin and unhealthy complexion. Because of these reasons human must obtain protein of food. The protein content and his biological value ranges widely of a different food. Milk protein has the most biological value because of it composition, balanced essential amino acids (EAA), good digestibleness and assimilability [1].

Curds is one of the most useful cultured milk products. It has good tastes and curative properties for the organism. Curds contains Vitamin В₁, В₂, РР, С etc. Curds provides hemoglobin formation in blood and the normalization of the nervous system function; consolidates bone and cartilage tissue; easily digested by the body; it is recommended for the prevention of metabolic diseases [2]. Human’s diet contents no curds because of his high cost and a shortage of raw milk. This situation must be changed. This can be achieved by increasing the yield of curds from the same quantity of milk without impairment of his quality. One of way to achieve increasing the yield of curds is the use of protein concentrates based on whey protein of milk and casein. Today scientific laboratories produce various protein concentrates with different mechanism of action. These are hydrolysates of whey proteins; L-PFI complexes which contain lactoperoxidase, lactoferrin, immunoglobulin G etc. “Optimilk” is the mixture based on casein, vegetable proteins and water-holding agents; “Milkmix” is the milk protein mixture with mass fraction of protein of 30 to 60%; “Molpro M” is mixture with mass fraction of protein 20%; “Stabiprot” is the mixture with mass fraction of proteins 35% and high [3]. Using protein concentrates in curds production; however, starter cultures of lactic acid bacteria don't always work well.

The goal of the report is the selection of optimal bacterial preparation and technological parameters of it insertion for curds production from milk of various quality with protein concentrate from factories of Leningrad region.

Market research of starter cultures are applied to dairy factories located in the Russian north-west showed that bacterial preparations of Interindustry Scientific Center “VNIMI”, “CHR HANSEN”, “DANISCO”, “SACCO” etc. are used most frequently. These preparations contain various mesophilic lactococcus and sometimes thermophilic lactic streptococci. All bacterial preparations possess acid formation activity and give clots with unequal sineritic properties [2,4].

At the first stage of work development curds production were applied with using of protein concentrate Stabiprot ZCME and bacterial preparations МТт and CHOOZIT TA LYO.

For curds production it was selected milk with various quantitative composition from different factories of Leningrad region. Total protein content in milk samples varied from 3,26% to 3,40%, casein varied from 2,8% to 3,1%, lactose varied from 3,6% до 4,8%, quantity of somatic cells ranged from 260 to 500 thousand per sm³. Curds were made of 1 liter of milk by the acid-rennet way. At the same time it was made curds production with bacterial preparation “MTt” produced by Russia and bacterial preparation “CHOOZIT TA LYO” produced by France. Raw milk was separated at the temperature 38-40^оС and after that obtained fat-free milk with mass fraction of fat 0.05% was pasteurized at the temperature 78^оС during 20 seconds and it was leavened by the bacterial preparation. 5% of the bacterial preparation was added. Leaven mixture was added 1% solution of rennet (1 gram per 1 ton of milk) and 40% solution of calcium chloride (400 grams per 1 ton of milk), previously dissolved in milk protein concentrate (5 grams per 1 ton of milk). The mixture was leavened at the temperature 30±2^оС as long as the titratable acidity of clot was equal 70-75^оТ. Ready clot was cut and was left him alone on 40 minutes for whey isolation. Isolated whey was partly deleted and clot was ladled at mylar bags and it was continued to separate whey by pressing. Obtained curds were cooled and weighed and after that it was determined the titratable acidity, the moisture content and quantity of curds. It was carried out visual and organoleptic estimation of clot, whey and curds.

Using of both types bacterial preparations and 0.5% of protein concentrate, quality and quantity of curds were made from milk with somatic cells low content (300 thousand per sm³ and less) and protein high content (3,35 – 3,40 %, including casein 2,95 – 3,10 %) (the first group of milk) were higher than the second group of milk with somatic cells content of 300 to 500 thousand per sm³, protein content of 3.26-3.3% (casein 2,80 – 2,90%)

Using of bacterial preparation “MTt”, quantity of standard moisture curds amounted to an average of 251 g per 1 liter of the first group of milk. The leaven duration was near 7 hours. Curds quantity amounted to an average of 237 g per 1 liter of the second group of milk and the leaven duration was 7,5-8 hours. Clots were dense, cleavable and well whey isolation. Curds had soft and crumbly consistency.

Using of bacterial preparation CHOOZIT TA LYO, quantity of standard moisture curds was almost the same as using of bacterial preparation “MTt” and it amounted to an average of 251 g and 238 g per 1 liter of milk respectively. The leaven duration of milk (the first group) was near 8 hours and the leaven duration of milk (the second group) was near 8,5-9 hours. Using of bacterial preparation CHOOZIT TA LYO, clots were visually dense and whey isolation was better to compare with bacterial preparation “MTt”. Ready curds consistency had better elastic, pronounced flavour and clean-flavored.

Thus, using of bacterial preparation CHOOZIT TA LYO, the leaven duration increased to approximately 1 hour and curds quantity didn’t change significantly and curds quality were slightly larger to compare with using of bacterial preparation “MTt”.

Bibliography :

1. Gunkova P.I., Gorbatova K.K. Biotechnological properties of milk proteins. –St.Petersburg: GIORD, 2015. – 216 p.

2. Kalinina L.V., Ganina V.I., Dunchenko N.I. Whole-milk products technology: Tutorial. –St.Petersburg: GIORD, 2008. – 248 p.

3. Kashevarova I.A. Quality improvement of cultured milk products and curds products // Dairy industry. – 2012. - №3. – P. 45 - 46.

4. Curds: Classification and microflora. [Electronic resource] http://konctanciya.info/post201668611/