Abstract
BackgroundPostprandial metabolic and appetitive responses of proteins are dependent on protein source and processing technique prior to ingestion. Studies on the postprandial effects of enzymatic crosslinking of milk proteins are sparse. Our aim was to study the effect of transglutaminase (TG)-induced crosslinking of sodium caseinate on postprandial metabolic and appetite responses. Whey protein was included as reference protein.MethodsThirteen healthy individuals (23.3 ± 1.1 y, BMI 21.7 ± 0.4 kg/m2) participated in a single-blind crossover design experiment in which the subjects consumed three different isovolumic (500 g) pourable beverages containing either sodium caseinate (Cas, 29 g), TG-treated sodium caseinate (Cas-TG, 29 g) or whey protein (Wh, 30 g) in a randomized order. Blood samples were collected at baseline and for 4 h postprandially for the determination of plasma glucose, insulin and amino acid (AA) concentrations. Gastric emptying (GE) was measured using the 13 C-breath test method. Appetite was assessed using visual analogue scales.ResultsAll examined postprandial responses were comparable with Cas and Cas-TG. The protein type used in the beverages was reflected as differences in plasma AA concentrations between Wh and Cas, but there were no differences in plasma glucose or insulin responses. A tendency for faster GE rate after Wh was detected. Appetite ratings or subsequent energy intake did not differ among the protein beverages.ConclusionsOur results indicate that the metabolic responses of enzymatically crosslinked and native sodium caseinate in a liquid matrix are comparable, suggesting similar digestion and absorption rates and first pass metabolism despite the structural modification of Cas-TG.
Highlights
Postprandial metabolic and appetitive responses of proteins are dependent on protein source and processing technique prior to ingestion
We recently found that TG-induced crosslinking of sodium caseinate modified both postprandial appetite and metabolic responses [20] after a test meal with a rather high protein concentration (13%), where the TG treatment changed the form of the test product from a high-viscous liquid to a strong gel
No significant differences were detected in postmeal glucose and insulin responses between Cas and Caseinate crosslinked by transglutaminase (Cas-TG) or between Cas/Cas-TG and Whey protein (Wh) beverages (P > 0.05)
Summary
Postprandial metabolic and appetitive responses of proteins are dependent on protein source and processing technique prior to ingestion. Studies on the postprandial effects of enzymatic crosslinking of milk proteins are sparse. Our aim was to study the effect of transglutaminase (TG)-induced crosslinking of sodium caseinate on postprandial metabolic and appetite responses. Despite the progress in our understanding of the regulation of postprandial metabolism and energy homeostasis, attempts to influence physiological mechanisms and Modification with crosslinking enzymes such as transglutaminase (TG) has been used extensively to change the functionality of proteins and thereby to improve the textural quality and stability of protein-based food products [7]. Despite the evidence on the benefits of TGinduced crosslinking in milk protein-based products, we are still a long way from fully understanding its effects on protein digestion in the gastrointestinal (GI) tract. Roos et al [13] reported that crosslinking of casein with TG does not inhibit proteolysis in vitro or digestibility in the intestinal tract of miniature pigs when fed as part of a mixed diet
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