36E-80

S. KELKAR, Biosystems and Agricultural Engineering, Michigan State Univ., 219 Farrall Hall, East Lansing, MI 48824, K. D. Dolan, Dept. of Food Science and Human Nutrition/Dept. of Agricultural Engineering, Michigan State Univ., 208 G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824-1224, and P. J. Oriel, Microbiology and Molecular Genetics, Michigan State Univ., 6192 Biomedical Physical Science Building, East Lansing, MI 48824-4320.

Traditional hard cider is made from mixtures of bittersharp and bittersweet cider apples, which contain high levels of polyphenols. However, these apple varieties are not widely available in the U.S. The U.S. cider market is in its nascent stages and growing at over 100% every year. At the same time, Michigan apple growers are looking for alternatives to utilize their excess apple produce. Hence, a study of fermentation of cider from Michigan apples will provide data to improve process design. Our objective was to measure levels of pH, sugar, alcohol, polyphenols and yeast growth in cider during fermentation of Michigan dessert apple juice. Jonathan apple juice was sulfited (50 ppm) to eliminate wild yeast and 0.3g/L of Saccharomyces bayanus yeast was added after 24 hours. Fermentations were carried out in 1L Pyrex bottles with airlocks at 19° C. Samples were evaluated every 24 hours in duplicates for pH and RI. The polyphenol content was measured using Folin-Ciocalteu method. Yeast concentrations were approximated using cytometry. Alcohol content was determined using an Ion Exclusion HPLC column and RI detector. Our results showed that fermentation reached completion after 9 days at 19° C. The pH of the samples remained constant at 3.29 with no significant change. The refractive index dropped from 9.8 (Day 0) to 4.6 (Day 9) (p<0.001). The polyphenol levels in fermenting cider showed an increase from 230 ppm (Day 0) to 342 ppm (Day 9) (p<0.01). The yeast followed an exponential pattern of growth. The alcohol content on days 0,3,6,9 were 0.0, 2.70, 4.01, 4.89 % v/v. These results serve as a guideline for manufacture of cider from American apples and indicate that fermentation may help increase the level of polyphenols in the final product. The data obtained can be used for modeling and optimization of the fermentation process.

Session 36E, Fruit & Vegetable Products: General
8:30 AM - 12:00 PM, Monday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana