Browsing by Author "Mao B"

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    Actinidin in Green and SunGold Kiwifruit Improves Digestion of Alternative Proteins-An In Vitro Investigation
    (MDPI (Basel, Switzerland), 2022-09-06) Kaur L; Mao B; Bailly J; Oladeji O; Blatchford P; McNabb WC; Recio I
    Both Hayward (green) and SunGold (gold) kiwifruit varieties contain a proteolytic enzyme, actinidin, that has been reported to enhance the upper tract digestion of animal proteins. Unlike the other gold varieties, which do not contain any actinidin, the SunGold variety contains significantly higher actinidin activity, but its activity is still much lower than that present in the green (Hayward) fruit. The objective of this study was to determine the effectiveness of actinidin in Hayward and SunGold kiwifruit in digesting alternative proteins, including pea protein, almonds, tofu, and quinoa. The protein sources were digested using a three-stage in vitro oral-gastro-small intestinal digestion model. The findings showed that both kiwifruit extracts enhanced the breakdown (observed through SDS-PAGE) for all the studied protein sources, particularly during gastric digestion, possibly due to higher actinidin activity at gastric pH. The increase in the rate of protein breakdown was probably due to the broader specificity of actinidin compared to pepsin. For many protein sources, most of the intact proteins disappeared within the first few minutes of gastric digestion with added kiwifruit extract. Green kiwifruit extract, due to its higher actinidin activity, had a higher effect on protein breakdown than the SunGold extract. However, for some proteins and under certain digestion conditions, SunGold extract resulted in higher protein breakdown. The latter, in the absence of any digestive enzymes, also led to some protein breakdown during the small intestinal digestion phase, which was not the case for the green kiwifruit extract. The green kiwifruit extract led to the greater breakdown of polypeptide chains of Pru-du 6, a major allergen in almonds. The results, for the first time, suggest that both Hayward and SunGold kiwifruit can lead to improved breakdown and digestion of alternative proteins when consumed as part of a meal; and therefore, have the potential to be used as a digestive aid in population groups looking to achieve faster and greater protein digestion such as athletes, elderly and people with the impaired digestive system.
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    Alternative proteins vs animal proteins: The influence of structure and processing on their gastro-small intestinal digestion
    (Elsevier Ltd, 2022-04) Kaur L; Mao B; Beniwal AS; Abhilasha; Kaur R; Chian FM; Singh J
    Background: Digestibility, an indicator of protein bioavailability, is essentially a measure of the susceptibility of a protein towards proteolysis. Proteins with higher digestibility have been linked with better health outcomes. Animal proteins are generally considered to be of better nutritional value than plant proteins not only because they are a good source of essential amino acids but also due to their higher digestibility in the human gastro-intestinal tract. With the recent emergence of alternative food protein sources, which are now processed in a completely new way to design new foods or new versions of the conventional foods, it has become extremely important to understand their digestion characteristics. Scope and approach: This review discusses the factors that affect protein digestibility, including protein source, structure, type of processing, and modification, with a particular focus on the effects of non-protein components present in food matrix. Key findings and conclusions: To obtain the desired functionality, particularly for alternate proteins, numerous physical, chemical, and enzymatic methods for modification have been reported. These modifications may alter structural characteristics of proteins by inducing structural modifications such as protein unfolding, crosslinking, and aggregation. Depending upon the protein reactivity during processing, the susceptibility of proteins towards hydrolysis by digestive enzymes might change, affecting not only the overall protein digestibility but also the rates of release of polypeptides and amino acids. The faster rates of protein digestion have been linked with muscle anabolism, suggesting the need and importance of classifying the new, emerging and alternative protein sources according to their rates of digestion into rapidly (RDP), slowly digestible (SDP) and resistant (RP) proteins. More research needs to be focussed on converting, through processing, the undigestible or RP into RDP or SDP to achieve better health outcomes.
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    Conformational changes and product quality of high-moisture extrudates produced from soy, rice, and pea proteins
    (Elsevier Ltd, 2024-02) Mao B; Singh J; Hodgkinson S; Farouk M; Kaur L
    This study aimed to investigate the performance of soy, pea, and rice proteins during high-moisture extrusion (HME) to understand better how the plant proteins transform into a fibrous structure. It found that rice protein isolate formed weak structures with the fewest layers and fibrous structures. Extruded pea protein concentrate produced more obviously layered structures than extruded soy and rice samples. Extruded soy protein isolate showed a compact gel structure, whereas extruded soy protein concentrate showed a thin fibrous structure. Meanwhile, the chewiness of soy and pea protein extrudates surpassed that of rice protein extrudates by approximately 10 N. After undergoing HME processing, there was a marked 5–10% decrease in extracted proteins (p < 0.05) in solvents with urea, dithiothreitol, and sodium dodecyl sulphate, when comparing the soy and pea extrudates with their raw materials, except for the extruded rice protein isolate (ERPI) with rice protein isolate. It could be deduced that HME processing promoted the formation of aggregates in soy and pea proteins that the extracted solvents could not dissolve. It also revealed that HME induced an increase in the content of S–S bonds in extruded soy and pea protein but a decrease in ERPI. The percentage of random coils in commercial pea protein, initially at 14.04%, saw a significant increase to 19.36% after extrusion (p < 0.05), indicating that pea protein is more likely to form intermolecular hydrogen bonds. In this study, the secondary structures of rice and soy protein did not show significant changes after extrusion.