Abdella Mohamed A A, Ahmed Samia A, Ibrahim Osama A
Chemistry of Natural and Microbial Products Department, Pharmaceutical and Drug Industries research institute, National Research Centre, Dokki, Giza, Egypt.
Chemistry of Natural and Microbial Products Department, Pharmaceutical and Drug Industries research institute, National Research Centre, Dokki, Giza, Egypt.
Int J Biol Macromol. 2023 Jan 15;225:361-375. doi: 10.1016/j.ijbiomac.2022.11.073. Epub 2022 Nov 11.
Enzyme-modified cheese (EMC) is a concentrated cheese flavor that is produced enzymatically from dairy substrates to provide an intense source of cheese flavor with broad applications. In this study, EMC was produced by enzymatic biotransformation from a new bacterial isolate described and molecularly identified as Bacillus thuringiensis strain-MA8. Optimization of protease production conditions using one-variable-at-a-time followed by multi-factorial (Plackett-Burman and Box-Behnken) designs increased production by 7-fold. Protease was used at different concentrations (300 and 900 U/100 g curd) as a cost-effective source of concentrated cheese flavor in the EMC preparation. Sensorial evaluation of EMC revealed that the overall acceptability, flavor, and texture were improved from the 2nd day compared to the control, and then decreased on the 4th day without any apparent bitterness. The chemical characteristics of EMC showed that the addition of protease extracts increased the total volatile fatty acids, water-soluble nitrogen, and acidity of EMC significantly (p≤0.05) compared to the control. The amino acids profile revealed that EMC1 which was treated with (300 U/100 g curd) protease had the highest essential amino acids (EAA) and EAA/total amino acids ratio. Nutritional parameters including protein efficiency ratio, biological value, and chemical score of EMC were higher than control based on Val, Met + Cys, Ile, Leu, and Phe + Tyr amino acids. Also, Scanning Electron Microscopy showed significant changes in EMC compared to the control. In conclusion, the addition of (300 U/100g curd) of protease revealed good EMC characteristics without any apparent defect.
酶改性奶酪（EMC）是一种浓缩的奶酪风味物质，通过酶法从乳制品底物中生产出来，可提供浓郁的奶酪风味，具有广泛的应用。在本研究中，EMC是由一种新的细菌分离株经酶促生物转化产生的，该分离株经描述和分子鉴定为苏云金芽孢杆菌菌株-MA8。采用一次单因素法，随后进行多因素（Plackett-Burman和Box-Behnken）设计对蛋白酶生产条件进行优化，使产量提高了7倍。在EMC制备中，蛋白酶以不同浓度（300和900 U/100 g凝乳）作为浓缩奶酪风味的经济有效来源使用。对EMC的感官评价显示，与对照相比，从第2天起总体可接受性、风味和质地有所改善，然后在第4天下降，且没有明显的苦味。EMC的化学特性表明，与对照相比，添加蛋白酶提取物显著提高了EMC的总挥发性脂肪酸、水溶性氮和酸度（p≤0.05）。氨基酸谱显示，用（300 U/100 g凝乳）蛋白酶处理的EMC1具有最高的必需氨基酸（EAA）和EAA/总氨基酸比值。基于缬氨酸、蛋氨酸+半胱氨酸、异亮氨酸、亮氨酸和苯丙氨酸+酪氨酸氨基酸，EMC的营养参数包括蛋白质效率比、生物价值和化学评分均高于对照。此外，扫描电子显微镜显示EMC与对照相比有显著变化。总之，添加（300 U/100g凝乳）蛋白酶显示出良好的EMC特性，没有任何明显缺陷。
