Adult and elderly in vitro digestibility patterns of proteins and carbohydrates as affected by different commercial bread types.

Carbohydrate and protein digestibility were assessed in different commercial bread types, i.e., soft, durum, and whole wheat, by applying in vitro digestion protocols mimicking adult or elderly physiological conditions. Protein digestibility was measured after the gastric and intestinal phases by the o-phthalaldehyde spectrophotometric assay (OPA). Carbohydrate digestibility was assessed by determining the incremental area under glucose curve during the intestinal phase of digestion to estimate the glycaemic index (GIe). Finally, the correlation between protein and carbohydrate digestibility was computed. Bread proteins presented a high gastric resistance, with a digestibility < 10% in all cases while after the intestinal phase, protein digestibility increased, ranging from 40 to 70%. Protein digestibility was affected both by formulation, with whole wheat bread presenting the lowest values, and by physiological conditions, with restrained digestibility under elderly conditions compared to adult ones. The GIe decreased in the order durum > soft > whole, under both adult (119, 101, and 82, respectively) and elderly (107, 93, and 65, respectively) conditions. The extent of differences under different physiological settings varied depending on the bread type, without significant changes for soft wheat bread (ΔGIe = 8), whereas elderly conditions significantly reduced GIe both for durum (ΔGIe = 12) and whole (ΔGIe = 17) wheat bread. An almost strong positive correlation between protein digestibility and GIe was observed (p = 0.69), indicating that concomitantly addressing sarcopenia and type 2 diabetes can only be pursued by a compromise solution or more desirably requires identifying technological strategies to maximize protein digestibility while restraining the glycaemic response.

Comparison of protein in vitro digestibility under adult and elderly conditions: The case study of wheat, pea, rice, and whey proteins.

In this study an in vitro static digestion method mimicking the elderly gastrointestinal conditions was designed by adapting the physiological parameters described in the INFOGEST standardized static in vitro digestion protocol, i.e., pH, digestive phase duration, concentrations of enzymes and bile salts, to the aged GI transit. The digestibility of proteins from different sources (pea, rice, wheat, and milk whey) was then assessed. Protein digestive behaviour was monitored after gastric and intestinal phases by BCA assay and SDS-PAGE to assess protein hydrolysis both from a quantitative and a qualitative point of view. Digested samples were also analysed for physical characteristics in terms of particle size and zeta potential. Data acquired under elderly gastrointestinal conditions were compared to those obtained by using the INFOGEST protocol designed to study adult digestion. Results clearly showed that the elderly gastrointestinal conditions deeply affected proteolysis leading to a general reduction of protein digestibility in comparison to the adult model. The proteolysis extent depended on the protein source with whey and rice proteins showing about 20% reduction using the model mimicking the elderly gut, followed by pea (about 10% reduction) and wheat (about 4% reduction) proteins. The knowledge of protein digestibility under elderly gastrointestinal conditions generated in this study could be useful in the attempt to develop age-tailored products.

Designing food for the elderly: the critical impact of food structure.

Ageing is an unavoidable progressive process causing many changes of the individual life. However, if faced in an efficient way, living longer in a healthy status could be an opportunity for all. In this context, food consumption and dietary patterns are pivotal factors in promoting active and healthy ageing. The development of food products tailored for the specific needs of the elderly might favour the fulfilment of nutritionally balanced diets, while reducing the consequences of malnutrition. To this aim, the application of a food structure design approach could be particularly profitable, being food structure responsible to the final functionalities of food products. In this narrative review, the physiological changes associated to food consumption occurring during ageing were firstly discussed. Then, the focus shifted to the possible role of food structure in delivering target functionalities, considering food acceptability, digestion of the nutrients, bioactive molecules and probiotic bacteria.

Effect of presence of gluten and spreads on the oral processing behavior of breads.

Little is known about the oral processing behavior of gluten-free (GF) products. This study investigated the oral processing behavior of one commercial GF bread and one gluten-containing (GC) equivalent with and without spreads. Oral processing parameters were determined through video recording and the predominant texture attributes were accessed using a check-all-that-apply test. The GF bread was perceived crumbly, dry and sandy and had a longer eating duration than the GC bread, which was perceived soft, spongy, pasty and sticky. Results suggest that the structure of the GF bread was easily fragmented during mastication and a longer period in the mouth was required to prepare a cohesive bolus for swallowing. The addition of spreads increased softness perception but did not affect chewing behavior. Oral processing behavior of GF products should be further investigated to understand how eating rate, satiation responses and food intake can be modulated in GF products.