Immobilization Techniques Applicable to Sourdough

Sourdough fermentation develops technological properties of bread and bakery products, improves sensory features, increases the shelf-life while bringing nutritional and health benefits of foods. During sourdough fermentation; enzymes such as protease, phytase, sucrase have been secreted through some biochemical and microbial reactions by lactic acid bacteria and yeasts. This action leads accumulation of metabolites giving the product unique characteristics and a high sensory quality. Immobilization of sourdough enzymes is favorable if compared to a free enzyme since the immobilization matrix may preserve a higher level of enzymatic activity. Immobilized enzyme preparations show the improved resistance and stability under harsh processing conditions, and numerous reuse can be possible for cost effectiveness. Sourdough fermentations can be carried out spontaneously or starter cultures can be applied to achieve uniform product manufacturing. Immobilization of starter cultures can be attributed as an applicable method to large scale manufacturing to increase the stability of cells during processing and storage. Various techniques such as spray-drying, fluid bed coating and freeze- or vacuum-drying have been evaluated for immobilization/encapsulation of starter cultures. Immobilization of sourdough enzymes and starter cultures and their industrial applications have not been thoroughly investigated yet. Therefore, this chapter mainly covers the immobilization by various techniques e.g. covalent binding, encapsulation, cross-linking, adsorption and entrapment applicable to sourdough. Immobilization applications to preserve nutritional value and health effects of sourdough to increase the shelf-life of products have been also reviewed in this chapter.