| With the continuous improvement of people's living standards and the increasing awareness of nutrition and health consumption,yak milk is increasingly valued and welcomed by consumers as a nutritious high-end dairy product.The yak(Bos grunniens)lives in the high-altitude areas in the northwest of China.Due to the restriction of transportation conditions and economic development level,the development of yak milk is still based on storage-resistant products such as milk powder,casein and UHT milk.The yoghurt with higher economic value is limited by the shelf life and storage and transportation conditions,and can only be sold in the yak milk producing area and surrounding areas,which severely limits the development of the yak milk industry.The CS content in yak milk is 79.5%,which makes yak milk have good curdiness,which is very suitable for processing solidified yoghurt.However,the yak yoghurt currently circulating in the market is not suitable for storage at room temperature,even under refrigeration conditions.It is only about 21 d,and the requirements of the whole process of cold chain also bring a lot of inconvenience to the transportation,storage and sales of yak yogurt.The subject introduces microwave sterilization technology into the processing of solidified long-acting yak yoghurt,which can retain the nutrients and flavor substances of yak yoghurt as much as possible,and maintain the condensed state of yoghurt.Entrusted by Gansu Xueyu Maozhen Co.,Ltd.,Gansu Light Industry Research Institute Co.,Ltd.is responsible for the research and development of long-acting solidified yak yogurt products.This study used yak milk as the research object.Through the single factor experiment,five strains suitable for the nutritional characteristics of high altitude hypoxia and yak milk were determined.Based on this,the best fermentation strains were determined by orthogonal test.Proportion;the test results were amplified by the test results of the strains,and the fermentation effect and fermentation stability of the compound strains were determined;the material thickness and microwave power were used as test parameters,and the material temperature,microbial lethal time,and production efficiency were Indicators,determine the optimal microwave sterilization parameters;determine the shelf life of the product through the shelf life test to develop a long-acting yak yogurt.The main conclusions are as follows:(1)The lactic acid bacteria of yak milk fermented by the single factor experiment were selected as Hansen No.2,Danisco 1,Rhodia No.1,Rhodia No.4 and Rhodia No.5;Cross-test to determine the optimal strain ratio of yak yogurt fermentation:Danisco 1: Rhodia 1: Rhodia 5: Hansen 2: Rhodia 4 = 1:1:1:2:6.According to the results of the best strain compound test,the pilot test of the pilot test was carried out to determine the optimal fermentation end point of the product was 72-78 °T.After 24 hours of fermentation,the obtained product acidity was 88-96 °T,and the sensory indexes of the finished products.Both reached a high level.(2)The microwave power and material thickness were used as parameters to determine the optimal microwave sterilization parameters of yak yogurt: microwave power 600 W,material layer thickness 53.08mm(bottom diameter 60 mm,ie 150ml),action time 1.55 min,in this condition Next,the number of lactic acid bacteria of the coagulated yak yoghurt is less than 10.(3)Accelerate the destructive test and long-term stability test through the shelf life,determine the shelf life of the microwave sterilization-solidified yak yoghurt,and determine its shelf life to be ?90d at normal temperature and ?180d under refrigeration.The solidified long-acting yak acid color produced by the process is white and yellowish,has the unique odor of the yak fermented milk,the structure is fine and uniform,the product quality is stable,and the product design,production and inspection standards are in line with the product quality standard GB19302-2010 Requirements for National Standards for Food Safety Fermented Milk.(4)The technology of this subject has been successfully transformed by Gansu Xueyu Zhenzhen Dairy Co.,Ltd.The company has an annual production capacity of2500 t solidified long-acting yak yoghurt.The product packaging specification is150g/cup,and the selling price is 6.0 yuan/cup.It can realize sales income of 71.25 million yuan,net profit of 5,500,600 yuan,and tax payment of 7,430,100 yuan.This topic has passed the evaluation of scientific and technological achievements in Gansu Province on December 12,2018,and completed the registration of scientific and technological achievements(Ganke promoted evaluation [2018] No.013).The evaluation results are: technical maturity level 13,technological innovation.Level 5,technical advancement level 5,ecological benefits,significant economic benefits. |
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