Date of Award
Master of Science
Food Science and Technology
H.O. Jaynes, J.R. Mount
The major objective of this experiment was to prepare an acidified canned product of peas which could be processed by a pasteurization method (boiling water bath) rather than by retorting. The effect of acidification on some chemical components, physical properties, microbiological counts and organoleptic characteristics was measured.
The percentage of vinegar affected the pH of the peas and liquor (0.01 level) and the acidity of liquor at the 0.05 level. Holding the samples in storage affected the acidity of peas and liquor (0.01 level) and the pH of liquor at the 0.05 level.
Firmness of the peas was increased (0.01 level) as the level of vinegar was increased in the acidified aqueous solutions. The amount of sugar in the sauces and the different sauces in which the peas were canned did not affect firmness.
Color of the peas was measured with the Hunter Colorimeter. Level of vinegar and sugar affected color significantly; however, the absolute difference in values was usually small. Mean values for peas canned in acidified solutions were: L = 46.9; "a" = -0.1; and "b" = 12.7. Mean values for rinsed peas which were canned in sauces were: L = 35.2; "a" = 0.3, and "b" = 15.2.
The level of vinegar did not affect the count of any of the microorganisms in samples of peas canned in the acidified solutions. The mesophilic and thermophilic aerobic counts were reduced during storage. On the first day of measurement, the highest estimated mean log count was 0.89 (colonies/g of sample).
For peas canned in the sauce the amount of vinegar or sugar had only a slight affect on the microbiological counts. The estimated mean log counts were: for mesophilic aerobes and anerobes 1.25 and 0.53, respectively; for thermophilic aerobes and anaerobes, 1.14 and < 0.04, respectively. The spices used to make the sauces contributed to the relatively high counts.
Samples of peas in which sauces were evaluated by a sensory panel for texture, flavor and overall acceptability were scored by use of a hedonic system.
Of all the experimental factors, only the level of vinegar affected texture (0.05 level). As the level of vinegar was increased, the peas became firmer causing the panelists to assign lower scores to the samples. On an 8-point scale (1 = dislike extremely; 8 = like extremely) the firmness scores ranged from 4.8 to 5.2 with a mean score of 4.9. The mean scores for flavor and overall acceptability was 4.7. These scores indicate that the samples were liked slightly. In general, the samples were too tart and too spicy. The peas were too firm.
Turner, Cherie L., "Effects of acidification of canned southern peas (vigna unguiculata) processed by a pasteurization method on some physical and organoleptic characteristics. " Master's Thesis, University of Tennessee, 1981.