The Study On The Processing Technology Of Direct-acidified Quark Cheese

The Quark cheese with the mildly acidic flavour is one kind of low fat. high calcium and protein dairy product,which is easily digested and popular with people. The high quality Quark should be smooth and easy to be spreaded. It is usually mixed with cream and consumed in various family dishes. The traditional Quark cheese is curd by rennin. The culture preserved condition has increased the pruduction cost, has the long time on manufacture, moreover the yield is low. Rennin is shortage now, so it is very important, moreover the cost of Quark cheese is very high, mostly consumer reject it. In this study a method of adding organic acids directly to produce quark cheese, replaces the use of rennet, saving production costs, is a new type of cheese making.For study of the process optimization of direct-acidified quark cheese, the citric acid was found to be the best acidifier acidified for the production of fresh-acid cheese by determinating the content of Ca,the content of moisture and the content of fat in this study. Maximum of 60.12% moisture content of direct-acidified quark cheese by using citric acid as acidifier, Least of 52.98% moisture content of direct-acidified quark cheese by using hydrochloric acid as acidifier, P>0.05 compared with the enzyme cheese, has no significant difference; Frankincense which the production of citric acid as acidifier is good, but the fine is not enough, sensory score is maximum of 88.12 points, frankincense which the production of hydrochloric acid as acidifier is no significant, quark cheese has irritation sour and very bitter, sense of significant gravel and has excellent texture and loose friable, sensory score is least of 71.53 points; Maximum of 106.32 mg/100g cheese the content of Ca of direct-acidified quark cheese by using hydrochloric acid as acidifier, least of 61.38 mg/100g cheese the content of Ca of direct-acidified quark cheese by using citric acid as acidifier, P<0.05 compared with the enzyme cheese, has significant difference; Maximum of 13.03% the content of fat of direct-acidified quark cheese by using hydrochloric acid as acidifier, Least of 11.02%the content of fat of direct-acidified quark cheese by using citric acid as acidifier, P<0.05 compared with the enzyme cheese, has significant difference.Compared to the traditional Quark cheese is curd by rennin, a method of adding citric acids directly to produce quark cheese, yield is 16.23% and corrected yield is 16.15% of acid coagulated cheese, lower than the enzyme coagulated cheese, solid content is 41.33% of acid coagulated cheese, lower than enzyme coagulated cheese, has difference about 4% between them, P> 0.5 no significant difference between them, content of Protein is 75.63% of acid coagulated cheese, has the less protein content, has difference about 1% between them, P> 0.5 no significant difference between them. And whey solids of direct-acidified Quark cheese is 57.46%, has to be slightly larger, a difference about 3%, P <0.05 has significant difference between them, acid coagulated cheese whey protein partial small is 24.22%, a difference about 0.4%, P> 0.5 no significant difference between them. Produced by direct acidification of the quark cheese Reduced production time, production time of enzyme coagulated cheese is 428min, production time of acid coagulated cheese is 175min, a difference about 4h, P =0 has significant difference between them.Different types of food gum such as starch, pectin, carrageenan, gelatin and xanthan gum, were used in direct-acidified quark cheese. The optimum food gum is A, Raw milk (Increases food gum)→Bactericidal(85℃,20min)→Plus CaCl2(0.02%)→Add citric acid(toPH4.6)→Cutting clot,Stir (10min)→Separate,Excluding whey→Cooling→Press forming→Packaging product, which was added before the bactericidal of food in plastic quark cheese by sensory evaluation to determine. The best dosage of modified starch is 0.5%; best dosage of pectin is 0.4%; optimum amount oxanthan gum is 0.3 %; best dosage of carrageenan is 0.4%; best dosage of gelatin is 0.3% were determined by OD value of whey, hardness, moisture content and sensory scores of Quark cheese. With increasing in the amount of starch of Quark cheese, yield and moisture content increased and no obvious improvement in hardness of cheese; With increasing in the amount of pectin of Quark cheese , hardness decreases, the moisture content of cheese followed by Great, but not significant increasing on cheese yield; with the addition of xanthan gum increasing, yield and moisture content increase with it, hardness decreases too; With increasing in the amount of gelatin, production rate and water content increase with it, hardness decreases with the addition of carrageenan, yield and moisture content of cheese increased with it, the hardness of cheese is not enough to improve significantly.To select starch, pectin and xanthan gum mixture each other, which has better effect by single factor experiments, measuring the compound in the colloidal synthesis by the OD values of whey, hardness, moisture content and sensory scorer,in order to determine the the bes production system when the total was 3% of food gum was:the modified starch and xanthan gum ratio of 7 : 5, the deformation of starch and pectin addition was 8 : 5, the pectin with the addition of xanthan gum ratio of 7 : 5.The best process parameters of direct-acidified fresh cheese were filtered out, that is processing factors influence the sensory quality of products as follows: the curd temperature>CaCl2 dosage> sterilization temperature, the optimum combination of: sterilization temperature is 83℃, CaCl2 0.02% addition level, the curd temperature is 55℃, the quality of fresh acid coagulated cheese the best.The final product was identified, the results show that the final product composition and health indicators are in line with the national department of agriculture soft cheese NY478-2002 standards. The direct-acidified quark cheese can be used in producing actually.