Stabilization mechanisms of oil-in-water emulsions by Saccharomyces cerevisiae

Production and Characterization of a Bioemulsifier Derived from Microorganisms with Potential Application in the Food Industry

There is a growing interest in the development and use of natural emulsifiers, which provide biodegradability as well as non-toxicity along with giving better performance compared to existing emulsifying agents used in the food industry. A large variety of sources of starting material, i.e., the microorganisms, are available to be used, hence giving a diverse range of applications. The focus of this review paper is on the production of bioemulsifiers, which are said to be "green surfactants", from fungi, bacteria and yeasts; furthermore, an overview pertaining to the knowledge gained over the years in terms of characterization techniques is reported. The methods used for the characterization and isolation such as TLC, GC-MS, HPLC, NMR have also been studied. The end-application products such as cookies, muffins, and doughs along with the methods used for the incorporation of bioemulsifiers, microorganisms from which they are derived, properties imparted to the product with the use of a particular bioemulsifier and comparison with the existing food grade emulsifiers has been discussed in detail. The future prospects indicate that newer bioemulsifiers with anti-microbial, anti-oxidant and stabilization properties will prove to have a larger impact, and emphasis will be on improving the performance at an economically viable methodology.

Yeast (Saccharomyces cerevisiae): evaluation of cellular disruption processes, chemical composition, functional properties and digestibility

The objective of this study was to evaluate yeast (Saccharomyces cerevisiae) from beer fermentation in its natural form (NY) and subjected to different processes of cellular ruptured [mechanical method using ultrasound (MRY) and modified autolysis using NaCl and ethanol (MAY)] regarding functional and digestibility properties, comparing them with textured soy protein (TSP). Ultrasound treatment resulted in 42% disruption efficiency and the micrographs obtained from scanning electron microscopy analysis showed important morphological modifications due to processes of cellular ruptured action. MRY cells presented more pronounced damage than LN, which suggests the rupture of the cell wall and exit of the internal material to the medium. NY, MRY, MAY, and TSP presented a very close composition concerning the protein content, ranging from 39.32 to 43.80% and moisture of 0.07-0.14%. In vitro digestibility of brewing yeast samples equated the digestibility of TSP (higher than 94%). Cellular disruption with ultrasound (MRY) caused an increase in foaming ability, stability and also oil retention capacity (8.82 mL of oil/g of protein). Modified autolysis (MAY) resulted in higher water holding capacity (14.50 g of water/g of protein) and index of water solubility (greater than 64%) with a decrease in their emulsifying properties. The highest water absorption capacity was presented by the TSP and NY. Therefore, in its different forms, yeast can be applied as a functional and technological ingredient in the food industry, with significant technological capabilities and potential applications.