Chemical Engineering Department, Institute of Chemical Technology, Mumbai 400019, India.
National Centre for Nanosciences and Nanotechnology, University of Mumbai, Kalina Campus, Kalina, Santacruz (E), Mumbai 400098, India.
Ultrason Sonochem. 2021 Mar;71:105368. doi: 10.1016/j.ultsonch.2020.105368. Epub 2020 Oct 19.
Hair waste in large amount is produced in India from temples and saloons, India alone exported approximately 1 million kg of hair in 2010. Incineration and degradation of waste human hair leads to environmental concerns. The hydrothermal process is a conventional method for the production of hair hydrolysate. The hydrothermal process is carried out at a very high temperature and pressure, which causes the degradation of heat-sensitive essential amino acids, thereby depleting the nutritional value. This work deals with alkaline hydrolysis of human hair using acoustic and hydrodynamic cavitation, and comparison with the conventional method. The optimal operating conditions for highest efficiency was observed, for the hydrolysis of 1 g of sample hairs in 100 mL of solution, at 4:1 (KOH: hair) ratio, soaking time of 24 h, the ultrasonic power density of 600 W dm (20 KHz frequency and input power 200 W) or hydrodynamic cavitation inlet pressure of 4 or 7 bars. Cavitation results in rupture of disulfide linkages in proteins and mechanical effects lead to cleavage of several hydrogen bonds breaking the keratin sheet structure in hair. Breakdown of bonds leads to a decrease in viscosity of the solution. 10% and 6% reduction in viscosity is obtained at optimal conditions for ultrasonic and hydrodynamic cavitation treatment, respectively. FTIR analysis of produced hair hydrolysate confirmed that the disulfide bonds in hair proteins are broken down during cavitation. The amino acid of hair hydrolysate, prepared using cavitation, has a relatively higher digestibility and nutritional value due to the enhancement of amino-acid content, confirmed using amino acid analysis. Cavitation assisted hair hydrolysate has a potential application in agricultural engineering as a fertilizer for improvement of the quality of the soil and land. Cavitation based hair hydrolysate can also be used as an environmentally friendly and economical source of essential amino acids and digestibles for animal or poultry feed.
在印度，大量的头发废弃物是从寺庙和发廊中产生的，仅 2010 年，印度就出口了约 100 万公斤的头发。废弃物中人类头发的焚烧和降解会引发环境问题。水热法是一种常规的生产毛发水解物的方法。水热法是在非常高的温度和压力下进行的，这会导致对热敏感的必需氨基酸降解，从而降低其营养价值。本工作涉及使用声空化和流体动力空化对人发进行碱性水解，并与常规方法进行比较。在水解 1g 样品毛发在 100ml 溶液中时，观察到最高效率的最佳操作条件为：KOH:毛发比为 4:1，浸泡时间为 24 小时，超声功率密度为 600W·dm（20kHz 频率和输入功率为 200W）或流体动力空化入口压力为 4 或 7 巴。空化会导致蛋白质中二硫键的断裂，机械效应会导致几个氢键的断裂，从而破坏头发中的角蛋白片层结构。键的断裂会导致溶液的粘度降低。在超声和流体动力空化处理的最佳条件下，分别获得了 10%和 6%的粘度降低。傅里叶变换红外光谱（FTIR）分析表明，毛发蛋白中的二硫键在空化过程中被破坏。用空化法制备的毛发水解产物的氨基酸分析表明，由于氨基酸含量的增加，其消化率和营养价值相对较高。由于 cavitation-assisted 毛发水解产物具有提高土壤和土地质量的潜力，因此它在农业工程中作为肥料具有潜在的应用价值。基于 cavitation 的毛发水解产物也可以作为动物或家禽饲料的必需氨基酸和易消化物的环保且经济的来源。
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