Exploration of pepsin diffusion in solid food particles by dynamic fluorescence techniques
2019
Rakhshi, Elham
Digestive enzymes diffusion, particularly pepsin in different food structures is a key factor to control protein-based foods digestion and absorption in the gastro-intestinal tract. The enzymes diffusion is believed to depend on food microstructure and dry matter content. This study aimed to investigate how the microstructure of complex food matrices after routine process (cooking) impacts pepsin diffusion. Four different foods (custard, pudding, sponge cake and biscuit) of identical dry matter ratio (i.e. comparable protein, lipid and sugar contents on dry basis) but different water contents were used as food models. Confocal imaging illustrated a gel-like protein-continuous structure in biscuit, pudding and sponge cake, whereas, a sol structure comprising of protein aggregates, lipid droplets and sugars suspended in a serum pool was observed for custard. FRAP analysis was exploited to calculate pepsin diffusion coefficients within the food matrices and the resulting data proved that an inverse correlation existed between pepsin diffusion and microstructure density. Results showed that with the decrease in water content a more compact and more homogenous network is observed in food matrices. Pepsin diffusion coefficient estimated by FRAP technique is significantly correlated to the dry matter following a non-linear order which is in line with obstruction-scaling model.
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