Digestibility of Processed Food Protein. In: Friedman M, editor. Nutritional and Toxicological Consequences of Food Processing. Boston: Springer US; 1991. pp. 371-88. [DOI: 10.1007/978-1-4899-2626-5_27]

Targeting the Gut Microbiota to Improve Dietary Protein Efficacy to Mitigate Sarcopenia

Sarcopenia is characterised by the presence of diminished skeletal muscle mass and strength. It is relatively common in older adults as ageing is associated with anabolic resistance (a blunted muscle protein synthesis response to dietary protein consumption and resistance exercise). Therefore, interventions to counteract anabolic resistance may benefit sarcopenia prevention and are of utmost importance in the present ageing population. There is growing speculation that the gut microbiota may contribute to sarcopenia, as ageing is also associated with [1) dysbiosis, whereby the gut microbiota becomes less diverse, lacking in healthy butyrate-producing microorganisms and higher in pathogenic bacteria, and [2) loss of epithelial tight junction integrity in the lining of the gut, leading to increased gut permeability and higher metabolic endotoxemia. Animal data suggest that both elements may impact muscle physiology, but human data corroborating the causality of the association between gut microbiota and muscle mass and strength are lacking. Mechanisms wherein the gut microbiota may alter anabolic resistance include an attenuation of gut-derived low-grade inflammation and/or the increased digestibility of protein-containing foods and consequent higher aminoacidemia, both in favour of muscle protein synthesis. This review focuses on the putative links between the gut microbiota and skeletal muscle in the context of sarcopenia. We also address the issue of plant protein digestibility because plant proteins are increasingly important from an environmental sustainability perspective, yet they are less efficient at stimulating muscle protein synthesis than animal proteins.

The Effect of Processing on Digestion of Legume Proteins

The domestic processing methods, soaking, cooking (traditional, microwave, pressure), and baking and the industrial processing, autoclaving, baking, and extrusion are used to improve consumption of legumes. The growing awareness of both health and sustainability turns the focus on protein (bio)availability. This paper reports the effect of these processing methods on the legume protein digestibility. Overall, the protein digestibility increases after processing by the different methods. However, since both the type of legume and the applied methods differ it cannot be concluded which specific method is best for the individual legume type.

Effects of processing methods on nutrient and antinutrient composition of yellow yam (Dioscorea cayenensis) products

There is dearth of documented information on nutrient retention of Dioscorea cayenensis products. This study was carried out to evaluate effects of processing methods on nutrient and antinutrient retention of yellow yam products. Fresh Dioscorea cayenensis tubers were purchased from Bodija market in Ibadan, peeled, cut into small pieces, divided into nine portions. One portion was treated as raw sample, and others processed into local delicacies. All nine samples were analysed for proximate, mineral, vitamin and antinutrient composition using AOAC methods. Data were analysed using ANOVA at p=0.05. Raw yam contained 66.79g moisture, 2.62g crude protein, 0.27g lipid, 0.17g fibre, 0.63g ash, 29.69g carbohydrates, 262.30mg potassium, 61.53mg magnesium, 0.79mg iron, 0.39mg zinc, and yielded 108.26kcal energy with insignificant vitamin content/100g edible portion. Processing significantly improved macronutrients and energy content with significant reduction in all antinutrients of products (p<0.05). The yam products can serve as staple source of energy to consumers.

Use of different spices as potential natural antioxidant additives on cooked beans (Phaseolus vulgaris). Increase of DPPH radical scavenging activity and total phenolic content

Herbs and spices, excellent sources of phenolic compounds, can be considered potential antioxidant additives. The use of spices must strike a balance between their potential antioxidant capabilities during preparation and the flavor acceptance, in order to avoid rejection of the food. The aimed of this study is to evaluate the influence of different spices and their concentrations on cooked common beans, focusing its potential as antioxidant additives. Onion, parsley, spring onion, laurel and coriander increased the antioxidant activity of preparation when used at 7.96 g of onion, 1.06 g parsley, 3.43 g spring onion, 0.25 g laurel (dry leaves), and 0.43 g coriander/100 g of cooked beans. Besides, these spices concentrations enhance total phenolics and alter the mixture protein digestibility minimally. For garlic samples it was not possible to establish a concentration that increases the antioxidant activity of cooked beans.

Germinated brown rice extract inhibits adipogenesis through the down-regulation of adipogenic genes in 3T3-L1 adipocytes

The aim of this study was to examine the anti-adipogenic effect of germinated brown rice methanol extract (GBR) in 3T3-L1 adipocytes. The GBR inhibited adipocyte differentiation was measured by Oil Red O staining and glycerol-3-phosphate dehydrogenase (GPDH) activity in a dose-dependent manner without initiating any cytotoxicity. The mRNA levels of adipogenic transcription factors such as CCAAT/enhancer binding protein (C/EBPα), proliferator-activated receptorγ (PPARγ), and sterol regulatory element-binding protein-1c (SREBP-1c), and adipogenic genes, such as fatty acid synthase (FAS), adipocyte fatty acid-binding protein (aP2), and lipoprotein lipase (LPL), were significantly down-regulated by treatment with GBR when compared to that of untreated control cells. Moreover, tumor necrosis factor-α (TNF-α) and interlukin-6 (IL-6) mRNA expressions were attenuated by GBR in mature adipocytes. These data suggest that GBR exhibits an anti-adipogenic effect through the suppression of adipogenesis in 3T3-L1 adipocytes.

Digestibility of extruded proteins and metabolic transit of N ε -carboxymethyllysine in rats

Milk proteins are frequently used as supplements in fortified foods. However, processing produces chemical changes which likely affect the nutritional advantage. This study was intended to explore the possible difference in digestibility between extruded and non-extruded caseins and how the dietary N (ε) -carboxymethyllysine (CML) is metabolised. Normal rats were randomized into either an extruded protein diet (EP) or the same with unextruded proteins (UEP), for two periods of 2 weeks at 7 to 9 and 11 to 13 weeks of age. However, no difference in protein digestibility was detected between the two diets, either in young or in adult animals, despite a 9.4-fold higher level of CML and an 8.5-fold higher level of lysinoalanine in the EP than in the UEP. No diet-related changes were observed in plasma CML, either protein bound or free. Amounts of 38 and 48 % of the orally absorbed CML were excreted in urine and faeces, respectively, in UEP-fed rats. Lower rates of excretion were found in the EP-fed rats (23 and 37 %, respectively). A second animal study using a single oral dose of free CML (400 μg/rat) was set up to measure the systemic concentration of CML every hour from 0 to 4 h. It revealed that protein-bound CML was not affected by the oral dose of CML, and the highest free CML level found in the circulation was 600 ng/mL. Extruded proteins, therefore, appear to be well digested, and CML rapidly eliminated. Since its elimination is, however, incomplete, the question of its biodistribution and metabolism remains open.

Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques

Egg proteins contribute substantially to the daily nitrogen allowances in Western countries and are generally considered to be highly digestible. However, information is lacking on the true ileal digestibility of either raw or cooked egg protein. The recent availability of stable isotope-labeled egg protein allowed determination of the true ileal digestibility of egg protein by means of noninvasive tracer techniques. Five ileostomy patients were studied, once after ingestion of a test meal consisting of 25 g of cooked 13C- and 15N-labeled egg protein, and once after ingestion of the same test meal in raw form. Ileal effluents and breath samples were collected at regular intervals after consumption of the test meal and analyzed for 15N- and 13C-content, respectively. The true ileal digestibility of cooked and raw egg protein amounted to 90.9 +/- 0.8 and 51.3 +/- 9.8%, respectively. A significant negative correlation (r = -0.92, P < 0.001) was found between the 13C-recovery in breath and the recovery of exogenous N in the ileal effluents. In summary, using the 15N-dilution technique we demonstrated that the assimilation of cooked egg protein is efficient, albeit incomplete, and that the true ileal digestibility of egg protein is significantly enhanced by heat-pretreatment. A simple 13C-breath test technique furthermore proved to be a suitable alternative for the evaluation of the true ileal digestibility of egg protein.