When peanut paste was stored at 30, 40 and 50°C for up to 1 yr, that held at 30°C for 161 days had minimal deteriorative changes. At SOY, the primary deterioration was increased browning, oxidized and cardboard flavors, and oil separation . Regression analysis indicated that ratings for chroma, cooked peanut, cardboard, and oxidized flavors were responsible for > 50% of the variation in response. When a detectable oxidized flavor was used as the indicator of storage deterioration, peanut paste had a predicted shelf life of 1.52 days at 30°C; 98 days at 40°C; and 96 days at 50°C.

The effects of temperature and number of water extractions on lipoxygenase, color, instrumental textural properties, hexanal in headspace volatiles, and sensory characteristics of peanut paste were determined. Water extraction at 60, 75, and 90C for 10 min resulted in 50, 95, and 100% reduction in lipoxygenase activity, respectively. Processing conditions significantly affected color lightness, hardness, cohesiveness, adhesiveness, hexanal, raw peanut flavor, and spreadability (P < 0.05). Water extraction at 90C for 10 min at least three times produced a more spreadable paste with less volatile hexanal and raw beany flavor than pastes subjected to the different treatments studied.

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