Sequential in Vitro Pepsin Digestion of Uncooked and Cooked Sorghum and Maize Samples

Abstract

An in vitro protein digestion study, using pepsin, was carried out in uncooked and cooked sorghum and maize flour samples. The digestibility values from the uncooked samples showed that sorghum presents digestibility values similar to those of maize. In the case of the cooked samples, it was found that a wet cooking procedure promotes a decrease in sorghum protein digestibility when compared to maize. Electrophoresis was used to follow the in vitro pepsin sequential digestion procedure, and infrared spectroscopy was applied to establish its efficiency. SDS-PAGE results showed that both uncooked samples (sorghum and maize) behave in a similar way. The wet cooking procedure increases the amount of high molecular weight aggregates and promotes the appearance of two nonreducible and nondigestible 45 and 47 kDa proteins. These two protein fractions are directly related to the loss of digestibility. It was also shown that in cooked sorghum the monomers (gamma-, alpha-, and beta-) are more resistant to digestion than the corresponding uncooked samples.

Gel Electrophoresis as a Tool to Study Polymorphism and Nutritive Value of the Seed Storage Proteins in the Grain Sorghum

“…1). These electrophoretic patterns correspond to kafirin spectra previously described in the literature (Shull et al, 1991;El Nour et al, 1998;Nunes et al, 2004). In our previous investigations (Table 2) we determined the relative content of different kafirin fractions and observed significant variation among different cultivars.…”

“…These polypeptides, perhaps, represent kafirin dimers, which were formed as a result of association of kafirin monomers. Earlier, the formation of similar polypeptides (45 kDa) was observed after the cooking process (Duodu et al, 2003;Nunes et al, 2004). Fig.…”

“…This method, originally applied by B. Hamaker and co-workers (Weaver et al, 1998;Aboubacar et al, 2001) has been used in a number of studies (Nunes et al, 2004;Wong et al, 2010). Application of this method allowed to isolate sorghum lines with high protein digestibility (Weaver et al, 1998) and to find out that -kafirin plays an important role in resistance of sorghum seed storage proteins to protease digestion, namely, -kafirin forms a disulfidebound enzyme-resistant layer at the periphery of protein bodies that restricts access of proteases to the inferior-located and more easily digested -kafirins (Oria et al, 2000).…”

Assessment of Algerian sorghum protein quality [Sorghum bicolor (L.) Moench] using amino acid analysis and in vitro pepsin digestibility

“…The other cultivars were characterized by very low digestibility, from 20% to 35%. The variability among cultivars was also shown by several authors (Duodu et al, 2002;Nunes, Correia, Barros, & Delgadillo, 2004;Zhao et al, 2008). With this information, it might be possible to select the most suitable cultivars for food application, regarding their digestibility and their protein contents.…”

Functional properties and in vitro digestibility of buckwheat protein products: Influence of processing

“…The in vitro digestibility of the proteins was evaluated by the method of Fu, Abbott, and Hatzos (2002) Nunes, Correia, Barros, and Delgadillo (2004), with some modification. Pepsin (Sigma, P7000, 1:10,000, 600-1000 units/mg) and trypsin (Genview, DH355-1, 1:250) were used for the in vitro digestion study.…”