The objective of this study was to investigate the influence of boiling, roasting and frying on the digestion of peanuts in simulated gastric environment. Raw and processed peanuts were tested for disintegration in a model stomach system. The differences in disintegration rate were explained with respect to the changes in moisture absorption and texture. The absorption of moisture and the swelling of peanuts during gastric digestion were studied using Magnetic Resonance Imaging (MRI). The results show that processing improved the gastric disintegration of peanuts, and the disintegration rate was in an order of fried > roasted > boiled > raw peanuts. The changes in total weight, moisture and the dry solid loss in the samples were described by Linear exponential equation, Peleg's equation and the Weibull equation, respectively. Absorption of gastric juice played a critical role in softening the texture contributing to the breakdown of peanuts. Static soaking test indicated that the disintegration rate, as indicated by half time, has a good exponential relationship with the textural parameters of soaked samples. MRI shows potential as being used to analyze the mass transfer phenomenon in solid foods under digestion. (C) 2012 Elsevier Ltd. All rights reserved.