Kombucha kůže: Příprava a charakterizace

Abstract

Kombucha leather is bacterial cellulose-derived leather developed as vegan leather possibly well-respond to consumers' expectations regarding safety, function, aesthetics, social responsibility, reducing pollution emissions of the leather industry, and also transforming the bio-wastes into useful materials. In this doctoral thesis, Kombucha leather was prepared via the combination between polymers and cellulose harvested from kombucha fermentation using bio-wastes that comprise two basic stages. In Kombucha-derived bacterial cellulose (KBC) production step, three investigated bio-wastes (sour whey waste, waste apple juice, brewer's spent grains) all displayed the brilliant efficiency in cellulose biosynthesis of Komagataeibacter xylinus compared to traditional kombucha and HS standard media, especially, superiority dry weight accumulated in trials containing sour whey waste (12.59 and 12.81 g/L). The fermentation optimization has then achieved an outstanding KBC dry weight (20.14 +- 0.62 g/L) accompanied by maximizing the amount of treatment-required waste with the optimum formulation of 1000 mL/L sour whey waste, 87.39 g/L cane sugar, 6 g/L black tea, and 78.91 mL/L bacteria volume, under 21 cultured days at 30 °C. Applying on the large containers, the most responsible fermentation batch was obtained at the cultured medium depths of 0.5 cm and low residual bacteria suspension volume of only 72.31 +- 8.74 mL. The characteristics of produced cellulose membranes show no significant differences for all samples compared to bacterial cellulose from HS standard medium. In Kombucha leather fabrication phase, leather-like mat based on KBC/PU/PLA exhibited remarkable mechanical properties compared to other components. Compressive temperature and time also directly affect structures and water resistance capacity of the prepared biocomposite. Especially, KBC were treated with dimethyldichlorosilane, hexadecyltrimethoxysilane, vinyltriethoxysilane, and 3- aminopropyltriethoxysilane have spectacular improved their hydrophobicity. This KBC modification also played a vital role in enhancing compatibility or homogenous blending to provide a stable structure for produced silane-treated KBC-based leather mat. Ultimately, the ingredient and condition of kombucha leather preparation were optimized with outstanding values of elastic modulus, biodegradable and water contact angle respectively reached at 44.07+-0.51 N/mm2, 1.31+-0.04 %, and 94.84+-1.590 from optimum leather-like mat containing KBC (13.74 % w/w), polyurethane elastomer (73.89 % w/w), and polylactic acid (12.50 % w/w), compressed at 155 °C for 5 min. Its morphology, chemical structure, thermal stability, mechanical strength, and biodegradability were characterized and compared to existing commercial leathers. Basically, the results show a possible response to the essential requirements of this Kombucha leather that prospective application in footwear, bags, or interior covering products.