Cryotropic gel-forming capacity of alfalfa (Medicago sativa L.) and fenugreek (Trigonella foenum graecum) seed galactomannans

Unravelling the functionality of anionic and non-ionic plant seed gums on milk protein cryogels conveying Lacticaseibacillus rhamnosus GG

Cryogels offer a promising macroporous platform that can be employed as either a functional ingredient in food composites or a colloidal template for incorporating bioactives, including probiotic living cells. The aim of the present work is to explore the functionality of two plant seed polysaccharides, flaxseed gum (FG) and alfalfa galactomannan (AAG), in individual and combined (1:1 ratio) milk protein-based cryogels, namely sodium caseinate (NaCas) and whey protein isolate (WPI). These cryogels were created by freeze-drying hydrogels formed via L.rhamnosus GG - a human gut-relevant probiotic strain - fermentation. Our findings showed that including gum in the composition limited volume contraction during lyophilisation, reduced macropore size and thickened cryogel skeleton vessels. Furthermore, gum-containing cryogels displayed improved thermal stability and slower water disintegration rates. The AAG-stabilised cryogels specifically showed a notable reduction in monolayer water content compared to FG. From a mechanistic viewpoint, AAG influenced the physicochemical and microstructural properties of the cryogels, most probably via its self-association during cryogenic processing, promoting the development of intertwined protein-gum networks. FG, on the other hand, enhanced these properties through electrostatic complexation with proteins. Cryogels made from protein-polysaccharide blends exhibited promising techno-functional properties for enhancing and diversifying food product innovation.

Impact of alfalfa (Medicago sativa L.) galactomannan on the microstructural and physicochemical changes of milk proteins under static in-vitro digestion conditions

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The impact of alfalfa galactomannan (AAG) on the digestibility of milk proteins was studied.

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AAG mediated the intragastric aggregation of both sodium caseinate and whey protein isolate.

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AAG affected only the peptic cleavage of caseins and β-lactoglobulin in the gastric chymes.

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AAG enhanced the free amino acids release in the gastric chymes regardless of the protein type.

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The free amino acids release rate in the intestinal chymes were adversely related to AAG content.

This paper reports on the impact of alfalfa galactomannan (AAG, 0.1, 0.5 or 1% wt.) on the colloidal changes and digestibility of sodium caseinate (NaCN) and whey protein isolate (WPI) dispersions (10% wt.) under static in-vitro digestion conditions. Static laser light scattering and confocal laser scanning microscopy-assisted assessment of the NaCN-based gastric chymes confirmed the ability of AAG to control the acid-induced protein coagulation phenomena. Contrarily, the presence of AAG in the WPI-based gastric chymes was associated with the formation of larger aggregates due to the occurrence of segregative microphase separation. The kinetic modelling of the SDS-PAGE densitometric data showed that the intragastric peptic cleavage rates were higher for caseins than whey proteins (β-lactoglobulin, α-lactalbumin). However, free amino acid (FAA) release rates did not exceed 12% under intragastric conditions, whilst notably higher release rates were achieved in the intestinal digesta (36–52%). In all cases, the FAA release rates significantly increased in the presence of AAG.