Manufacture and biochemical characteristics during ripening of Cheddar cheese with variable NaCl and equal moisture content
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- Møller, K.K., Rattray, F.P., Høier, E. et al. Dairy Sci. & Technol. (2012) 92: 515. doi:10.1007/s13594-012-0076-3
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Reduction of salt in ripened cheese presents an industry challenge due to its profound role in flavour and texture development. This study investigated the biochemical impact of varying the salt concentration in Cheddar cheese while maintaining the moisture content constant, with particular emphasis on proteolysis. Cheeses containing 0.9, 1.3, 1.8 and 2.4 % (w/w) salt and 37.7 ± 0.2 % (w/w) moisture were manufactured by parallel adjustment of the curd grain size, cooking temperature and time, cheddaring, curd chip size and rate of salting and analysed over the course of 270 days ripening. Salt reduction affected chymosin and starter lactocepin activities to accelerate casein degradation and accumulate derived peptides at rates correlating positively or (mostly) inversely with salt concentration. The kinetics of αS1-CN(f1–23) and N-terminal peptides produced thereof and of β-CN(f193–209) were studied in detail. Plasmin activity was affected by cooking treatment and (small) pH differences during ripening but appeared limited overall, due to low levels of pH. Starter lysis showed a strong positive dependency on the salt concentration, and resultant lower contents of free amino acids upon salt reduction were evident. In essence, salt reduction caused a marked decrease in the ratio of peptidase to proteinase activity. Remedies to counterbalance this ratio were discussed in order to avoid excessive accumulation of bitter peptides and promote the stage of maturity. Salt variation left cheese identity unaltered, and the concept of moisture equalisation was proposed as an initial measure to produce high-quality salt-reduced Cheddar.
KeywordsCheddar Salt reduction Cheese ripening Proteolysis
降低成熟干酪中食盐的含量对干酪的风味和质地有较深远的意义,因此该举措目前是工业化生产低盐干酪所面临的一个挑战。该研究考察了切达干酪在水分含量保持不变的情况下盐浓度的变化对干酪生化特性的影响,特别强调蛋白酶解的影响。干酪加工过程中保持水分含量37.7 ± 0.2 % (w/w)不变,使干酪食盐含量分别为0.9、1.3、1.8 和2.4 % (w/w) ,调整干酪凝块颗粒大小、加热温度和时间、凝块碎片大小保持一致,分析干酪在270d的成熟过程中的生化特性。实验结果表明,盐浓度的降低影响了凝乳酶和细胞膜蛋白酶的活性从而加速了酪蛋白的降解和肽的累积,酪蛋白降解速率与盐浓度的降低呈正相关或与盐浓度刚好相反。研究了αS1-CN(f1–23)、N-末端肽和β-CN(f193–209)的动力学。血纤维蛋白溶酶活性在干酪成熟过程中受加热温度和pH的影响,但是由于干酪的pH较低,这种影响不十分明细。发酵剂溶菌的程度依赖食盐的浓度,在盐浓度降低时游离氨基酸的净累积量降低。实际上,盐浓度的降低造成了肽酶和蛋白酶活的比值显著下降,弥补了由于这两种酶活比例的不平衡而导致过多苦味肽形成的问题,并促进了干酪的成熟。因此,在实际生产中,考虑盐浓度的变化以及水分平衡是生产高质量低盐切达干酪的首要措施。