The development of biodegradable materials from microbial exopolysaccharides has extraordinary potential to be applied in food packaging. Kombucha tea is a fermented drink produced by a symbiotic community of bacteria and yeasts, where a by-product based on bacterial cellulose is generated at the surface of the beverage. In this work, novel materials based on the integral kombucha tea by-product were developed from the floating and the intentionally submerged discs of biomass. Each disc was dispersed in water and subjected to ultrasonic homogenization. Films obtained by casting exhibited high homogeneity without cracks with a microstructure composed by a homogeneous and continuous cellulosic matrix of ribbon-shaped nanofibers. Infrared spectroscopy and thermogravimetric analyses indicated the further presence of low and high molecular weight compounds. The increase in glycerol content in the film decreased glass transition temperature and increased flexibility, hydration, and water vapor permeability. Films obtained from submerged discs had an additional plasticization given by substances incorporated during the immersion in the culture medium. Both types of films made from the floating and the submerged disc had a natural and remarkable antioxidant activity of 69 ± 2% and 72 ± 2% of radical inhibition, respectively, probably due to polyphenols or other compounds from the culture medium. Results revealed that using the integral cellulosic by-product of kombucha tea to prepare films could be advantageous due to the cost-effective process (no separation, no purification), interesting physical–chemical properties, and the retention of natural bioactive substances.

Graphical abstract

由微生物胞外多糖开发可生物降解材料具有在食品包装中应用的巨大潜力。康普茶是一种由细菌和酵母的共生群落生产的发酵饮料，饮料表面会产生基于细菌纤维素的副产物。在这项工作中，从漂浮的和有意淹没的生物量圆盘中开发了基于完整的康普茶茶副产品的新型材料。将每个圆盘分散在水中并进行超声均质化。通过流延获得的膜表现出高均质性，没有裂纹，其微观结构由带状纳米纤维的均匀且连续的纤维素基质组成。红外光谱和热重分析表明还存在低分子量和高分子量化合物。膜中甘油含量的增加降低了玻璃化转变温度，并增加了柔韧性，水合性和水蒸气渗透性。从浸没盘获得的膜具有额外的增塑作用，该增塑作用是在浸入培养基中的过程中掺入的物质引起的。由浮动盘和浸没盘制成的两种类型的膜均具有自然和显着的抗氧化活性，分别具有69±2％和72±2％的自由基抑制作用，这可能是由于培养基中的多酚或其他化合物引起的。结果表明，使用康普茶的纤维素副产物制备薄膜可能是有利的，因为该过程具有成本效益（无需分离，无需纯化），

图形概要