Baker's Yeast Quality Evaluation for Repacking and Storage under ...

Deterioration(%)Journal of Applied and Industrial Sciences, 2013, 1 (2): 6-15, ISSN: 2328-4595 (PRINT), ISSN: 2328-4609 (ONLINE)123503002502001501005001 2 3 4 5 6 7 8 9 10 11 12 13 14Storage time (w eek )Fig. 2: The deterioration percentage of sample B stored at room temperature (30 o - 35 o C) and sample B-1 stored in refrigerator(7 o - 10 o C)Fig. 3: The deterioration percentage of sample C stored at room temperature (30 o - 35 o C) and sample C-1 stored in refrigerator(7 o - 10 o C)At zero time of the storage, samples A, B and C had similarspecific volumes ranging between 4.70 and 4.88 cc/gr. Duringthe period of storage yeast samples behavior were summarizedin Table (9). The specific volume values exhibited significantdecreases (at P< 0.05 level) with the storage. The specificvolumes of bread containing the yeast strains stored at theroom temperature for one week, dropped to 4.80, 4.71 and4.61 cc/gr for the samples C, A and B, respectively. Aftereight weeks storage, these values were drop to 3.35, 3.21 and3.17 cc/gr for samples C, A and B, respectively and theserecords indicated poor quality bread. Similar findings werefound with the samples stored in the refrigerator for elevenweeks of storage. The bread containing yeast strains stored inrefrigerator had higher specific volumes than that containingyeast strains stored at the room temperature. These resultsindicated that, the yeasts stored at room temperature, in opencontainers, gave poor bread quality after seven weeks ofstorage. Whereas, the yeasts stored in the refrigeratortemperature gave poor quality bread after eleven weeks ofstorage. One possible reason for this is that, baker’s yeast issusceptible to deterioration during storage, as a result ofdecreasing in the viable counts, and does not retain sufficient