Apple pieces as immobilization support of various microorganisms

Abstract

The biocatalyst prepared by immobilization of Saccharomyces cerevisiae strain AXAZ-1 on apple pieces was used for fermentation of grape must both in batch and continuous system. The immobilized yeast showed an important operational stability without any decrease of its activity. In continuous process, the bioreactor was operated for 95 days without any diminution of the ethanol productivity. Concentrations of higher and amyl alcohols were low indicating an improved quality product. Apple pieces were also used as support for immobilizing Kluyveromyces marxianus IMB3 for high-temperature (45 °C) wine-making. The fermented grape must contained 3–4% alcohol and semi-sweet wines were produced by the addition of potable alcohol. Preliminary sensory evaluation of the produced wines ascertained the fruity aroma and the overall improved quality compared to other commercially available products. Lactobaccillus casei cells immobilized on apple pieces were used for probiotic, fermented milk and lactic acid production. Apple-supported L. casei used for successive fermentation batches of whey proved to be very effective and suitable for food-grade lactic acid production. The immobilized biocatalyst was also used for milk fermentation and was able to ferment after storage for 15, 98 and 129 days at 4 °C, while no infection was reported during storage periods.