Effect of stressful malolactic fermentation conditions on the operational and chemical stability of silica-alginate encapsulated Oenococcus oeni

Abstract

Oenococcus oeni was encapsulated into inter-penetrated polymer networks of silica-alginate (SiO2-ALG). Fourier transform infrared spectroscopy analysis proved the presence and the polycondensation of the siliceous material used in SiO2-ALG capsules. Environmental scanning electron microscopy showed that the structure of SiO2-ALG biocapsules was rougher than in alginate (ALG) biocapsules. The behaviour of SiO2-ALG biocapsules was evaluated at pH 3.0–3.6 and alcohol degrees of 12–15%. Repeated-batch malolactic fermentations (MLF) demonstrated that SiO2-ALG biocapsules can be reused efficiently for five times in either low-pH or high-ethanol wines, while free bacteria only can be used once under the most favourable MLF conditions. The inclusion of siliceous materials into ALG hydrogel improved the stability of the biocapsules, reducing their shrinking and achieving an excellent integrity under winemaking conditions. These results proved the possibility of industrial application of SiO2-ALG biocapsules in winemaking.