| Braised pork belly with preserved vegetable is a Chinese traditional meat product.Relying on the innovation of food processing and package,retort pouched braised pork belly with preserved vegetable has realized a large-scale production and commercial sales,which can be stored at room temperature for more than 6 months,be ready-to eat and can realize a quick reheating.But consumers are usually more cautious when choosing retorted products because the sensory quality of retorted products is worse than fresh products.Besides,nutrients of retorted food may change during the long-term storage,which has negatively affected the industrial development.It is important to study braised pork belly with preserved vegetable,especially its change of nutritional quality and flavor quality for improving the production process and guiding the consumption.In this study,the in vitro protein digestibility,digestion products and the composition of fatty acids were compared among three brands of braised pork belly with preserved vegetable.Then the effects of steaming time and storage time on protein digestion were studied to get the optimized steaming time and storage time.Based on the above results,the quality attributes of braised pork belly with preserved vegetable made of Suhuai pig and of Sanyuan pig were compared.Hopefully,the results can be applied for the further development of meat products made of local pig breeds.1.Differences in quality attributes among three brands of braised pork belly with preserved vegetableThe in vitro protein digestion and the fatty acid composition of braised pork belly with preserved vegetable from three brands(A,B,and C)were compared.The results showed that there was no significant difference in protein digestibility among the three products.LC-MS/MS results showed that there were differences in the composition and the abundance of peptides in the digestion products.Samples of brand C had the largest total number of peptides.The fat content and the fatty acid composition among three brands were significantly different.The crude fat content of samples of brand A was significantly lower than those of the other two samples.There were significant differences in 11 fatty acids among the three branded samples,of which 8 fatty acids had an important effect on product differentiation(VIP>1).It is inferred that the differences in digestibility and digestion product of three different brands may come from the different process,especially of the heating process,as well as the pork breed.2.Effects of steaming time on quality attributes of braised pork belly with preserved vegetableIn the process of braised pork belly with preserved vegetable,the heating temperature is usually fixed while the heating time depends on the experience of operators,which is an important factor for the product quality.In this study,the single-factor simulation experiment was applied to compare the sensory,nutritional and flavor attributes of braised pork belly with preserved vegetable when the product was steamed for 30 min,60 min,90 min and 120 min following with 30 min of sterilization in boiling water in the laboratory.The results showed that the steaming time had an influence on the sensory quality of products,and the product steamed for 90 min had the highest sensory scores.The products steamed for 60 min had the highest protein digestibilities with 23.32%for pepsin digestion and 60.89%for pepsin-trypsin digestion.The electrophoresis and particle size analyses illustrated that the degree of protein aggregation and enzymatic hydrolysis varied with steaming time,which led to the differences in band composition and optical density.In total of 65 volatile compounds were detected.There were 15 common compounds.The samples steamed for 30 min had the lowest relative content of alcohols,but the highest aldehydes.The relative abundances of alcohols,ketones,acids and heterocycles were relatively high in samples steamed for 90 min,which contributed to a good flavor.In conclusion,the product steamed for 90 min had the best quality.3.Effect of storage time on quality attributes of braised pork belly with preserved vegetableIn order to study the effect of storage time on the quality of braised pork belly with preserved vegetable,fresh samples were produced under the optimized steaming time.Then the braised pork belly with preserved vegetable was stored at 4? for 0,2,4,and 6 weeks.As the sensory quality of the samples stored for 6 weeks decreases significantly and they became inedible,only the samples stored for 0,2,and 4 weeks were digested with pepsin and trypsin at each time point.There was no significant difference in the in vitro digestibility among the three groups of samples.However,the digested products were significantly different.The peptide composition in the digested products of the samples stored for 2 weeks and 4 weeks were similar.The number of peptides with oxidative modification increased along with the storage time.On this basis,the commercial retorted samples were studied.Samples were produced according to the factory process as well as the optimized steaming time.Then the braised pork belly with preserved vegetable was stored at 25? for 0,1,2 and 4 months and the samples were digested with pepsin and trypsin at each time point.Products stored for 1 month had the highest protein digestibility(47.68%)while decreased significantly since the second month of storage(35.40%).SDS-PAGE analysis indicated that no significant differences were observed in band intensity of the majority of bands in undigested samples and pepsin-digested samples along with the storage time.And the results of LC-MS/MS showed that the samples stored for 1 month had 412 peptides in pepsin/trypsin digested products.According the result of PLS-DA,storage time was more effective to pepsin digestion than to pepsin-trypsin digestion.As the storage time increased,the crude fat content of the products increased and the GC results showed that the fatty acid profile changes occurred mainly in the first 2 months of storage.The quality of braise pork belly with preserved vegetable decreases along with the storage time and the product stored for less than 2 months has a relatively high quality.4.Efffect of pork breed on quality attributes of braised pork belly with preserved vegetableTo study the effect of pork breed on the quality of braised pork belly with preserved vegetable,the products made of the local breed-Suhuai pig were compared with those made of crossbred Sanyuan pig.The Suhuai pig products had better sensory scores in color,texture,aroma and the overall likings than those made of crossbred pig meat.There was no significant difference between two products in protein digestibility and the particle size before digestion,however,the particle size of digested products made of Suhuai pig meat was smaller than that of crossbred pig meat.31 and 40 volatile substances were found respectively in the two products and a total of 13 common substances.The relative content of a majority of volatile substances which contribute to the flavor in the Suhuai pig products was higher than those in crossbred pig products.In conclusion,pork breed has an effect on the quality of braised pork belly with preserved vegetable as the product made of Suhuai pig meat had better quality attributes than that of crossbred pig meat. |
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