| Bacon, also named smoked meat, is a kind of commonly consumed traditional meat products in western countries. In our country, there are similar bacon products, Chinese bacon, which is also a famous traditional meat product with local flavour characteristics. But these bacon products could produce harmful polycyclic aromatic hydrocarbons (PAHs) because of using smoking process, which are deemed to have potential safety hazard to the body health. This greately affected the acceptability of consumer towards traditional bacon products. The traditional dry-cured meat products, such as dry-cured hams and dry-cured chicken produced by using dry-curing and drying-ripening processes, are deeply favored by the consumer for their unique flavour. For this reason, the purpose of this study was to process a new kind of bacon product using for reference of the wind-drying and ripening processes of traditional dry-cured ham in order to avoid the smoking of traditional process. And on this basis, the processing parameters were further optimized through studying the effects of processing conditions on the changes of moisture and salt contents, proteolysis, lipolysis and lipid oxidation during processing and the sensory quality of final bacon products. The research content mainly includes the following three sections:1. Studies on the physicochemical changes, proteolysis, lipolysis and lipid oxidation in Chinese bacon during processing.Chinese dry-cured bacon was processed with pig bacon belly by dry-curing3days and drying-ripening18days. The changes of physicochemical parameters, proteolysis, lipolysis and lipid oxidation were investigated as well as their correlations with processing factors (moisture, NaCl content, pH and weight loss) were analyzed by determining the physicochemical, proteolytic and lipid oxidative indices in bacon during processing. The results showed that the proteolysis became intense with temperature rising up to29.5℃. The contents of non-protein nitrogen (NPN) and free amino acids (∑FAA) and proteolytic index markedly increased. POV and TBARs values also significantly increased after drying-ripening12days, and reached the peaks until the end of drying-ripening, which are0.055g/100g lipids and0.42μgMDA/g meat, respectively, for POV and TBARs. But both of them were lower than the safety limits, especially the POV was far lower than national safety limit (0.055g/100g). All the above results indicated that increasing drying-ripening temperature could accelerate proteolysis, lipolysis and lipid oxidation and promote the formation of flavour. Whereas, when drying-ripening up to6days, then the high process temperature (29.5℃-39.5℃) could cause the intense moisture loss, and only41.14%moisture retained until the end of drying-ripening18days, the sensory quality of the bacon product was very poor. So, under the intensifying high-temperature ripening condition, the process time could not too long during dry-cured bacon processing. When the bacon drying-ripening for6days, the temperature increased to about30℃, at this time the moisture content of bacon was about50%and the characteristic flavour was full-bodied, the product had a good sensory quality.2. Effect of daubing edible coatings on physicochemical quality of Chinese bacon during processingThe poor water retention property and severe lipid oxidation during Chinese bacon process greatly affected the product sensory quality. To deal with these limitations, chitosan and alginate sodium were coated on the surface of Chinese bacon after dry-curing. The physicochemical quality of Chinese bacon was studied by measuring the moisture content, TBARs value and color of products. The results showed that:At the end of processing, the surface moisture content of treatment groups coating chitosan and alginate sodium membrane were higher4.32%and4.85%, respectively, than that of the control group; TBARs values of the treatment groups were always significantly lower than the control group during processing, which indicated that coating treatment had marked anti-lipid oxidation effect; In addition, the results also showed that the coating treatment also significantly improved the apparent color. Either coating chitosan membrane or coating alginate sodium membrane could significantly increase the brightness value and red degree value of the products, the red degree value increased2.28and2.88compared to control treatment, respectively. To sum up, all the above results indicated that the coating chitosan treatment could better maintain the moisture content and product color and anti-oxidation.3. Process of Chinese bacon and its effects on physicochemical quality indices and proteolysis The effects of processing time, dry-ripening temperature, the time of chitosan coating and amount of added salt on the physicochemical quality and proteolysis of dry-cured bacon products were investigated by L9(34) orthogonal experiment. The results showed that:the proteolysis index(P.I.%) and total free amino acids (FAA) significantly increased (p<0.05) with the rising of temperature during processing:The P.I.%and∑FAA of17-32℃treatment group increased20%and28%, respectively, compared with the treatment group of13-28℃. TBARs was significantly correlated with process temperature (r=0.93, p<0.01), and its maximal value is0.65±0.26mg/kg. The sensory quality of Chinese bacon could be improved by shortening process time. The product with59.75±1.89%moisture and3.49±0.49%salt had a better sensory quality. The synthetical optimized processing using∑FAA and the total score of sensory evaluation as target functions was: process time5day, dry-ripening temperature17-32℃, coating two times and amount of added salt1.5%. |
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