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pH changes in smokeless tobaccos undergoing nitrosation during prolonged storage: effects of moisture, temperature, and duration

Andersen, R.A., Fleming, P.D., Hamilton-Kemp, T.R., Hildebrand, D.F.
Journal of agricultural and food chemistry 1993 v.41 no.6 pp. 968-972
water content, smokeless tobacco, tobacco, plant products, pH, nitrosamines, chemical reactions, storage, pyridine alkaloids, heat treatment, alkalinity
Three smokeless tobacco research products were each adjusted to two moisture levels before storage for 48 weeks at 24 and 32 degrees C. The pHs of high water content moist snuff (55.5%) and dry snuff (remoisturized to 51.4%) increased 0.3-2.1 pH units during the storage. In contrast, the pHs of decreased water content moist snuff (21.9%) and dry snuff (12.3%) decreased by 0.2-0.4 unit. Chewing tobacco pHs at high (49.3%) and low (22.3%) moisture levels and at each moisture-temperature treatment decreased during storage. Nitrosated pyridine alkaloids increased only in tobaccos that became more alkaline during storage. Interactions between the effects of moisture and temperature occurred. Heating snuffs at 100 degrees C for 30 min at zero storage time prevented the increases of pH, nitrosamines, and nitrite observed in non-heat-treated controls during storage. The results support the view that increases of nitrosamines may be mediated by microbial growth.