Epsilon Archive for Student Projects

Abstract

The interest for locally produced food is increasing due to consumer concern about the environment, distrust of industrial foods and a demand for high quality products. Apple is the predominant fruit crop in Sweden, and by processing apples into cider and vinegar, these products could significantly contribute to the development of the market of local foods.

In this study different yeast types and different bacterial cultures were evaluated for their suitability in cider and vinegar production from cloudy apple juice. Ten apple cultivars (Aroma, Baldwin, Belle de Boskoop, Bramley, Cortland, Gravensteiner, Ingrid-Marie, Jonathan, Rubinola and Spartan) were also evaluated for their suitability for production of juice, cider and vinegar. Chemical analyses including total soluble solids, titratable acidity and total phenols were performed on the products along with sensorial evaluation by taste panels.

The yeast strains were shown to have an effect on fermentation rate and the resulting content of total phenols in ciders fermented from cloudy apple juice. Dry commercial starter strains gave a higher appreciated cider compared to cider that was spontaneously fermented, and the ale yeast Safale S-04 was concluded to be the most suited for fermentation of cloudy apple juice.

For vinegar production, the bacterial culture had an effect on TSS, but not on any other chemical or taste characteristics. Clear differences in acceptability were found between the cultures; the culture from Alles um den Essig, intended for the submerged method, seemed to better be suited to the used production system compared to cultures developed for the surface method.

The cloudy apple juice from the different cultivars varied significantly in chemical composition, with TSS in the range of 9.6–15.1%, TA 0.41–1.24% and total phenols 123.9–850.0 mg GAE/L. The comparatively sweet juices of Jonathan and Spartan obtained the highest acceptance whereas juices with lower TSS/TS ratios were less acceptable by the taste panel. During fermentation into cider, the TSS decreased differentially in the cultivars, whereas the differences in TA and total phenols were unaffected. Ciders that were perceived to be comparatively sweet were accepted to a higher degree. The fermentation enhanced the taste differences between the cultivars, and Jonathan and Spartan, were also most accepted as ciders. For vinegar, the differences in traits decreased, and of all the chemical parameters only content of total phenols separated the cultivars. There was however a tendency of lower acceptance of vinegar from Belle de Boskoop, Gravensteiner and Jonathan.

It was concluded that several aspects influence the quality of cloudy apple juice, cider and vinegar, including cultivar, ripeness and choice of microorganisms for fermentation. For juices and ciders, sweeter products were preferred to a large extent, and the TSS/TA ratio appears to be a good predictor of consumer acceptance. In this study, an apple cultivar with a juice of good taste generally also produced a good cider, whereas the cultivar was of less importance for vinegar production.