Starch digestion kinetics and mechanisms of hydrolysing enzymes in growing pigs fed processed and native cereal-based diets.

This study aimed to examine in vivo starch digestion kinetics and to unravel the mechanisms of starch hydrolysing enzymes. Ninety pigs (23 (sd 2·1) kg body weight) were assigned to one of nine treatments in a 3×3 factorial arrangement, with starch source (barley, maize, high-amylose (HA) maize) and form (isolated, within cereal matrix, extruded) as factors. We determined starch digestion coefficients (DC), starch breakdown products and digesta retention times in four small-intestinal segments (SI1-4). Starch digestion in SI2 of pigs fed barley and maize, exceeded starch digestion of pigs fed HA maize by 0·20-0·33 DC units (P<0·01). In SI3-4, barley starch were completely digested, whereas the cereal matrix of maize hampered digestion and generated 16 % resistant starch in the small intestine (P<0·001). Extrusion increased the DC of maize and HA maize starch throughout the small intestine but not that of barley (P<0·05). Up to 25 % of starch residuals in the proximal small intestine of pigs was present as glucose and soluble α(1-4) maltodextrins. The high abundance of glucose, maltose and maltotriose in the proximal small intestine indicates activity of brush-border enzymes in the intestinal lumen, which is exceeded by α-amylase activity. Furthermore, we found that in vivo starch digestion exceeded our in vitro predictions for rapidly digested starch, which indicates that the role of the stomach on starch digestion is currently underestimated. Consequently, in vivo glucose release of slowly digestible starch is less gradual than expected, which challenges the prediction quality of the in vitro assay.

Eight-day consumption of inulin added to a yogurt breakfast lowers postprandial appetite ratings but not energy intakes in young healthy females: a randomised controlled trial.

Increasing feelings of satiety may reduce appetite and energy intake. The role of inulin consumption in impacting satiety is unclear. A randomised double-blind controlled crossover trial aimed to determine the effects of inulin+yogurt on satiety after 1 and 8-d consumption. The preload breakfast included 100 g vanilla yogurt with (yogurt-inulin (YI)) and without (yogurt-control (YC)) 6 g inulin. A total of nineteen healthy females (22·8 (sd 2·7) years) with non-restrained eating behaviour and taking hormonal contraceptives participated in the study. Day 1 and 8 visual analogue scale (VAS) ratings of Hunger, Fullness, Desire to Eat and Prospective Food Consumption (PFC) were collected at fasting and every 30 min for 180 min. Energy intake was calculated from a weighed ad libitum lunch and remainder of day food records. Total AUC was calculated for each VAS. Day 1 (VAS only) and 8 (VAS and energy intakes) data were compared between YI and YC using ANCOVA, and ANOVA was used to compare energy intakes on Day 1. There were no significant differences between Day 1 YI and YC AUC appetite ratings or energy intakes. However, 8-d consumption of YI v. YC was associated with lower Desire to Eat and PFC ratings but similar lunch and total day energy intakes. Therefore, the addition of 6 g inulin to a commercially available yogurt affected feelings of appetite, but not energy intake, after repeated consumption. These results suggest that inulin may be a suitable ingredient to increase dietary fibre consumption, with potential to impact appetite.

Sialylated galacto-oligosaccharides and 2'-fucosyllactose reduce necrotising enterocolitis in neonatal rats.

Necrotising enterocolitis (NEC) is one of the most frequent and fatal intestinal disorders in preterm infants and has very limited treatment options. Breast-fed infants are at a 6-10-fold lower NEC risk than formula-fed infants, and we have previously shown that human milk oligosaccharides (HMO) improved survival and reduced pathology in a rat NEC model. The HMO disialyllacto-N-tetraose (DSLNT) was most effective, and sialylation was shown to be essential for its protective effect. Galacto-oligosaccharides (GOS), currently added to some infant formula, but not containing sialic acid, had no effect. In addition to DSLNT, our previous work also showed that the neutral HMO fraction, which contains high concentrations of 2'-fucosyllactose (2'FL), slightly improved pathology scores. Here, we assessed the in vivo efficacy of 2'FL, as well as of GOS that we enzymatically sialylated (Sia-GOS). Neonatal rats were randomised into the following study groups - dam-fed (DF), formula-fed (FF), FF containing pooled HMO (10 mg/ml), GOS (8 mg/ml), Sia-GOS (500 µm) or 2'FL (2 mg/ml) - and subjected to the established NEC protocol. The DF and HMO groups had the lowest pathology scores with mean values of 0·67 (sd 0·34) and 0·90 (sd 0·47), respectively. The FF group had significantly elevated pathology scores of 2·02 (sd 0·63). Although the addition of GOS to the formula had no protective effect and generated scores of 2·00 (sd 0·63), the addition of Sia-GOS or 2'FL significantly lowered pathology scores to 1·32 (sd 0·56) (P<0·0034) and 1·43 (sd 0·51) (P<0·0040), respectively. The results warrant further studies to investigate the underlying mechanisms and to assess safety and efficacy in human neonates.

Spatial distribution of functional components in the starchy endosperm of wheat grains.

The starchy endosperm of the mature wheat grain comprises three major cell types, namely sub-aleurone cells, prismatic cells and central cells, which differ in their contents of functional components: gluten proteins, starch, cell wall polysaccharides (dietary fibre) and lipids. Gradients are established during grain development but may be modified during grain maturation and are affected by plant nutrition, particularly nitrogen application, and environmental factors. Although the molecular controls of their formation are unknown, the high content of protein and low content of starch of sub-aleurone cells, compared to the other starchy endosperm cells types, may result from differences in developmental programming related to the cells having a separate origin (from anticlinal division of the aleurone cells). The gradients within the grain may be reflected in differences in the compositions of mill streams, particularly those streams enriched in the central and outer cells of the starchy endosperm, respectively, allowing the production of specialist flours for specific end uses.