| The carcass of beef cattle after slaughter needs to remove acid,age and form a variety of flavor substances.At present aging methods mainly include wet and dry aging.Dry aging has prominent flavor and good tenderness,but at the same time there are more weight loss and the microbial contamination.Some researchers have found that the moisture-permeable bags can reduce weight loss of beef and better simulate the flavor of dry aging beef.However,the mechanism of the effect of moisture-permeable bags on beef quality has not been studied deeply.Therefore,in this study,four different types of moisture-permeable bags with different moisture permeability were selected to study the effects of moisture-permeable bags on the edible quality,flavor substances and myofibril degradation of beef aging for 0,7 and 14 d.The main research contents and results are as follows:1.Effect of packaging with moisture-permeable bags on the edible quality of beefIn this chapter,350,5000,7900 and 11,000 g/m2/24 h moisture permeability bags and dry-and wet aging methods were used to age for 0,7 and 14 d respectively to explore the effects of aging methods on the edible quality of aging beef.The results showed that weight loss of aging beef could be effectively controlled by the moisture-permeable bags(P<0.05),and the moisture-permeable bags increased with the increase of moisture permeability.The L*and b*value of dry aging were significantly lower than the groups of moisture-permeable bags and wet aging(P<0.05).There was no significant difference about pH among treatments(P>0.05),but the pH significantly increased with the aging time(P<0.05).With the increase of moisture permeability,the shear force,hardness,cohesiveness and chewiness in the texture of beef decreased gradually(P<0.05).The aerobic bacterial count,mold and yeast increased with the increase of moisture permeability.The scores of tenderness and juiciness in sensory evaluation increased with the increase of moisture permeability,but the odor score was the opposite,and there was no significant difference in color and overall liking among treatments(P>0.05),To sum up,the t groups of 7900 and 11000 g/m2/24 h had better edible quality.2.Effect of packaging with moisture-permeable bags on flavor of beefIn this chapter,350,5000,7900 and 11,000 g/m2/24 h moisture permeability bags and dry-and wet aging methods were used to age for 0,7 and 14 d respectively to explore the effects of aging methods on the flavor of aging beef.The results of the electronic nose showed that the overall aroma was significantly separated at 7 and 14 d after aging.In the group with high moisture permeability,the types of flavor substances were more,and alcohols and esters significantly increased(P<0.05),while the groups of high moisture permeability were higher than dry aging;The results of electronic tongue showed that the overall taste of the treatments was significantly different at 7 and 14 d,which were mainly reflected in bitterness and umami.With the increase of moisture permeability,the content of total free amino acids increased gradually,and the bitter amino acids and umami amino acids had the same tendency.There was no difference of total free amino acids between the groups of high moisture permeability(7900 and 11000 g/m2/24 h)and dry aging(P>0.05),while the difference was not significant between the groups of low moisture permeability(350 and 5000 g/m2/24 h)and wet aging(P>0.05).Degradation of odorant nucleotides occurred,and the odorant nucleotides content of the high moisture permeability groups was significantly higher than that of the low moisture permeability groups(P<0.05).However,the odorant nucleotides content of the high moisture permeability groups had no difference compared with dry aging(P>0.05),when the difference was not significant between the groups of low moisture permeability and wet aging(P>0.05).3.Effects of packaging with moisture-permeable bags on myofibril degradation and structure of beefIn this chapter,350,5000,7900 and 11,000 g/m2/24 h moisture permeability bags and dry-and wet aging methods were used to age for 0,7 and 14 d respectively to explore the effects of aging methods on the degradation and structure of myofibrillar protein in aging beef.The fragmentation index increases with the increase of moisture permeability and aging time.The percentage content of free water and bound water decreased gradually with the increase of moisture permeability,but the percentage content of uneasily flowing water increased gradually.Surface hydrophobicity increased with the increase of moisture permeability and also with the increase of aging time.In the secondary structure of dry aging treatment,the content of the α helix decreased significantly(P<0.05),but the content of the βbend increased significantly(P>0.05),and the random curl and P fold did not change significantly(P>0.05).There was no significant difference in desmin degradation degree at 7 d(P>0.05),and desmin degradation degree at high moisture permeability group and dry aging was significantly higher than that at low moisture permeability treatment group and wet aging at 14 d(P>0.05).In general,the high moisture permeability treatment groups can increase the flavor substances of beef and simulate the flavor of dry ging beef.In general,the moisture-permeable bags affected the protein structure of beef,and the degradation degree of myofibrin increased with the increase of moisture permeability. |
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