Limited hydrolysis of β‐casein by cell wall proteinase and its effect on hydrolysates's conformational and structural properties |
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| Authors: | Xiaofen Ren Daodong Pan Zhen Wu Xiaoqun Zeng Yangying Sun Jinxuan Cao Yuxing Guo |
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| Affiliation: | 1. Food Science and Technology Department of the Marine Science School, Ningbo University, Ningbo, China;2. Food Science and Nutrition Department, Nanjing Normal University, Nanjing, China |
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| Abstract: | Optimisation of enzymatic hydrolysis of β‐casein with cell envelope proteinase (CEP) from Lactobacillus acidophilus JQ‐1 to produce the angiotensin‐I‐converting enzyme (ACE) inhibitory peptides using response surface methodology (RSM). Under optimal conditions (enzyme‐to‐substrate (E]/S]) ratio (w/w) of 0.132 and pH of 8.00 at 38.8 °C), the ACE inhibitory activity of hydrolysates was 72.06% and the total peptides was 11.75 mg mL?1. Scanning electron microscopy (SEM) micrographs indicated that the tightness of the β‐casein surface structure was gradually weakened and small holes appeared after enzymatic treatment, while Fourier transform infrared spectroscopy (FTIR) spectra indicated remarkable changes in the chemical composition and macromolecular conformation of β‐casein after enzymatic hydrolysis. Differential scanning calorimetry (DSC) analysis indicated that the corresponding hydrolysates had higher thermal stability. The enzymatic hydrolysis also led to an increase in the free sulfhydryl content of β‐casein hydrolysates compared with raw β‐casein, which led to the increase in the antioxidant activity of β‐casein hydrolysates. |
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| Keywords: |
cell envelope proteinase
hydrolysates structural properties β ‐casein |
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