The Effect Of Sous Vide Cooking On The Quality And Safety Of Chicken Legs

Sous vide cooking is a new processing method that heats vacuum-packed food with low temperature and long time.Compared with the traditional cook method,it can make the product keep better taste by reducing the water loss and the damage of thermosensitive nutrients greatly.This method is used in food processing widely,but few studies on the effect of sous vide cooking on the quality and safety of chicken.In this paper,chicken legs were used as raw material to explore the effect of different sous vide heating conditions on the quality of chicken legs meat,and sous-vide samples were compared with traditional boiling and frying products.To investigate the formation of heterocyclic amines under different heating conditions,and the microbial safety of sous-vide products under low temperature and normal temperature were also studied.The results are as follows:Firstly,the effects of heating time,temperature and salt addition on nutrient content were studied.The specific conclusions were as follows: temperature and salt addition had obvious effects on water content(p<0.05).With the increase of temperature,the water content decreased gradually.With the increase of salt content,it showed an upward trend and reaching the maximum value when salt content was 2%.The fat content increased significantly with the rise of temperature(p<0.05),the maximum value was obtained at 80?.With the increase of time and salt content,it had an opposite trend.Time,temperature and salt addition had all significant effects on TBA value and vitamin PP content(p<0.05).TBA value reached maximum value at 75? and then decreased gradually.The content of vitamin PP reduced with the increase of time,temperature and salt addition.The optimum cooking combination of sous vide obtained by the orthogonal test were 75?,6 h and 1% salt.Secondly,the changes of cooking loss,nutritional composition and color difference were analyzed by comparing sous vide cooking with traditional boiling and frying methods.The results showed that the three cooking methods had significant effects on the loss rate of water,protein,vitamin pp and the retention rate of calcium,iron and phosphorus(p<0.05).Among three cooking method,frying had the highest loss rate,and sous vide cooking had the lowest loss.The sous-vide sample had the highest L*,and fried sample had the highest a* and b*.The sensory score showed that sous-vide chicken legs can maintain good tenderness and juiciness and fried samples can have attractive color and flavor,so the further studies should be took to make sous-vide foods have better color and flavor.Thirdly,The microbial indexes of sous-vide chicken legs during different storage conditions were studied.The grow trends of total colonies,lactic acid bacteria and Bacillus cereus in 25 days were determined.The results showed that the storage period could exceed 25 days under refrigerating condition and was about one week at room temperature.Lactobacillus was the dominate bacteria and bacillus cereus was detected at room temperature.So,sous-vide chicken legs stored at room temperature for a long time may have food safety risks,it is recommended to storage under refrigeration conditions.Fourthly,the content of heterocyclic amines in chicken legs under different heating conditions and heating methods were studied,and the inhibition of antioxidants on heterocyclic amines was also determined.The results showed that the heating time,temperature and the salt addition had significant effect on the change of heterocyclic amines content in sous-vide chicken legs(p<0.05).IQ was not detected under any heating conditions,while the contents of MeIQx,4,8-DiMeIQx and total heterocyclic amines increased with the increase of time,temperature and salt addition.The content of heterocyclic amine in chicken meat cooked in three different ways were higher than that in chicken skin.IQ can be detected in fried chicken legs,but not in other two methods.The content of heterocyclic amine in fried chicken legs was significantly higher than that in boiled products and sous-vide samples.The inhibitory effect of synthetic antioxidants was higher than that of natural antioxidants.PG had the best inhibitory effect as single antioxidant,and the inhibitory rate reached 59.8%.The combined use of PG+BHA had the best effect than both other conditions,and the inhibition rate was about 77.5%.