不同温度和时间下散养鸡鸡蛋感官、微生物以及氨基酸变化分析

Research on change of sensory,bacterial and amino acids index of randomly rearing chicken’s eggs in different storage temperature/duration

为研究散养鸡鸡蛋在不同温度和时间下感官指标、微生物数目以及氨基酸成分的变化,试验选取信阳市不同散养鸡场随机采集同一日龄、大小均匀、品质良好的鸡蛋200枚进行试验。将200枚鸡蛋随机分为2组,每组100枚,分别放置在4℃冰箱和25℃恒温箱两种条件下储存,每隔7 d取样,测定所取样品的蛋重、蛋黄指数、蛋清pH、菌落总数、大肠杆菌和沙门氏菌的数目,同时每隔14 d取样分析氨基酸成分的变化。结果表明:4℃和25℃条件下贮藏的鸡蛋其蛋重、蛋黄指数会随储存时间的延长而降低,4℃条件下,28 d时蛋重较1 d时下降了8.09%,但差异不显著(P>0.05),35 d时蛋黄指数较1 d时下降了14.89%,差异显著(P<0.05),25℃条件,28 d时蛋重最低和1 d相比降低了14.86%,差异显著(P<0.05);14 d时蛋黄指数较1 d降低了31.91%,在21 d时蛋清pH较1 d时增加了19.50%,差异显著(P<0.05)。鸡蛋内部微生物的数量也会随储存时间的延长而明显增加,4℃条件下,35 d时蛋黄中沙门氏菌、蛋清中的大肠杆菌和沙门氏菌数目分别是28 d的53.37倍、5.27倍和3.44倍(P<0.05)。25℃条件下,28 d时蛋黄中菌落总数、蛋清中菌落总数、蛋黄中大肠杆菌和沙门氏菌数目、蛋清中大肠杆菌和沙门氏菌数目分别是21 d的19.71倍、17.65倍、6.43倍、3.70倍、52.67倍和17.15倍;氨基酸总量(TAA)、必需氨基酸(EAA)含量、非必需氨基酸(NEAA)含量均有所降低,4℃下储存的鸡蛋各氨基酸含量无显著变化,25℃下的鸡蛋在储藏过程中其苯丙氨酸(Phe)、蛋氨酸(Met)、赖氨酸(Lys)含量出现显著差异(P<0.05)。综上,散养鸡鸡蛋感官品质、微生物数量以及氨基酸含量与储存时间呈正相关,与储存温度呈负相关,其4℃条件下鸡蛋品质下降程度较小。

In order to study the changes of sensory index,microorganism number and amino acid composition of eggs at different temperature and time,200 eggs from several chicken farms in Xinyang city were randomly divided into 2 groups.The eggs were stored in 4℃refrigerator and 25℃thermostat,respectively.Samples were taken every 7 d or 14 d,and 10 uniform non-destructive samples were taken from each group.The changes of egg weight,egg yolk index,egg white pH,total bacterial count,number of Escherichia coli and Salmonella and amino acid composition of the samples were measured.The results showed that the egg weight and yolk index of eggs stored at 4℃and 25℃decreased with the extension of storage time.At 4℃,the egg weight at 28 days was 8.09%lower than that at 1 d,but the difference was not significant(P>0.05).The yolk index at 35 d was 14.89%lower than that at 1 d,and the difference was significant(P<0.05).Under 25℃,the egg weight at 28 d was 14.86%lower than that at 1 d,and the difference was significant(P<0.05).On the 14th day,the egg yolk index decreased by 31.91%compared with the 1d,and the egg white pH increased by 19.50%on the 21 d,and the difference was significant.The number of microorganisms in eggs also increased significantly with the extension of storage time.At 4℃,the number of Salmonella in yolk,Escherichia coli and Salmonella in egg white at 35 d was 53.37,5.27 and 3.44 times that of 28 d,respectively(P<0.05).At 25℃,the total number of colonies in egg yolk,the total number of bacteria in egg white,the number of Escherichia coli and Salmonella in egg yolk,and the number of Escherichia coli and Salmonella in egg white were 19.71,17.65,6.43,3.70,52.67,17.15 times of those in 21 d,respectively.;The contents of total amino acids(TAA),essential amino acids(EAA)and non-essential amino acids(NEAA)decreased.There was no significant change in the amino acid content of eggs stored at 4℃,and the phenylalanine(Phe),methionine(Met)and lysine(Lys)contents of eggs stored at 25℃were significantly different(P<0.05);However,due to different storage methods,at the same time,compared with the eggs stored at 25℃,the changes of multiple indicators of eggs stored at 4℃will be slower.The results of this study indicated that eggs had better quality preservation effect under low temperature storage,and the shorter the storage time was,the smaller the egg quality decreased.