Digestible Content Research Articles

43 Approaches for improving nitrogen utilization efficiency and environmental sustainability of pork production systems

Abstract Nitrogen (N) is an essential element for life, but due to its inefficient utilization, N waste and emissions generated have exceeded the planetary boundaries and ability of the Earth to effectively overcome these environmentally detrimental effects. Global food animal production contributes 29 to 34% of total global N emissions, with pork supply chains contributing about 16% of these emissions. Life cycle N use efficiency (NUE) of U.S. pork production is only about 56%, which is similar to broiler (55%) and egg (50%) production, but greater than beef (10%) and milk (31%) production. However, only about 10 to 44% of dietary N is converted into edible pork products. While genetic improvement has increased NUE associated with improved lean growth rate, improvement in litter size has led to an increased proportion of low-birth-weight pigs that have reduced NUE. Although metabolic modifiers including porcine somatotropin, ractopamine, and immunocastration improve NUE, they are not feasible or acceptable to consumers in many countries. Separate sex feeding and reducing market weight can also improve NUE. Ultimately feeding program design and implementation have the greatest potential to improve NUE because feed is associated with 70% of N emissions in pork production systems. Multi-objective feed formulation using Life Cycle Assessment environmental impact data of feed ingredients, precision feed formulation and feeding practices to overcome variability in digestible nutrient content of feed ingredients and nutritional requirements of pigs fed in groups, feed processing to enhance energy and nutrient digestibility, and minimizing feed wastage offer the greatest opportunity to improve NUE and environmental sustainability. There are substantial differences in greenhouse gas emissions and embedded water and land use associated with growing-finishing feeding programs depending on the dietary proportions of corn, soybean meal, distillers dried grains with solubles (DDGS), and crystalline amino acids among U.S. geographic regions. Furthermore, addition of thermally processed supermarket food waste to corn-soybean meal (CSBM) diets can significantly reduce environmental impacts and diet cost without compromising growth performance and carcass composition compared with current commercial feeding programs. Although growing-finishing feeding programs using CSBM diets with minimal crystalline amino acids result in greater N intake, N retained, and urinary N excretion compared with feeding low protein, crystalline amino acid supplemented (LP) diets, and diets containing 30% DDGS, growth performance and carcass composition are optimized and impacts on climate change, marine and freshwater eutrophication, and fossil resource are reduced by feeding CSBM diets compared with feeding LP or DDGS diets. Sourcing and using feed ingredients with reduced environmental impact metrics along with precision diet formulation and feeding practices to ensure “getting the right amount of energy and nutrients in the right feed fed to the right pigs at the right time” can improve NUE and environmental sustainability of pork production systems.

497 Amylase supplementation influences nutrient digestibility regardless of corn type in broiler chicken diets

Abstract Corn is the primary energy supply in the broiler chicken diet. Physical and nutritional characteristics related to corn endosperm can affect nutrient utilization, as well as the inclusion of exogenous enzymes. This study aimed to evaluate two different corn types classified according to endosperm traits in diets for broiler chickens supplemented or not with amylase. Male broiler chickens (n = 360; 1-d old Cobb 500) were allocated in metabolic battery cages and randomly assigned in a 2 x 2 factorial arrangement (2 corn types; 2 amylase doses: 0 and 90 g/t of diet). A hardness test was performed to categorize and classify each corn type according to breakage force. Corn endosperms were assessed through scanning electron microscopy to investigate structure variations of starch granules. From 19 to 21 d, excreta samples were collected to estimate apparent total tract retention (ATTR) of nutrients and apparent metabolizable energy (AME). On d 26, ileal digesta content was collected to determine apparent ileal nutrients digestibility (AID) and ileal digestible energy (IDE). Data were analyzed using the Student t-test for hardness test (P < 0.05). The Tukey test was performed with a significance declared of 5% to compare the averages obtained for ATTR and AID using the GLM procedure on R Software. Differences were observed in the hardness test (P < 0.05), which classified each corn type either as hard (217 N) or soft (166 N; Table 1). The SEM highlighted structural variations between the floury and vitreous endosperm of each corn. In soft corn, starch granules were more dispersed in the floury endosperm, with a less dense distribution observed in the vitreous endosperm compared with hard corn (Figure 1). However, hard corn exhibited a more compact starch granules distribution in both floury and vitreous endosperm. No differences were observed (P > 0.05) in ATTR of dry matter, crude protein, or AME attributed to corn type, but amylase supplementation improved ATTR of dry matter (P = 0.015) and crude protein (P = 0.020; Table 2). On AID, corn type affected (P = 0.041) dry matter coefficient, and amylase supplementation significantly improved dry matter (P = 0.019), crude protein ileal digestibility (P = 0.012), and IDE (P = 0.018). No interactions between corn type and amylase supplementation were observed (P > 0.05). These findings demonstrated that amylase supplemented in broiler diets impacts nutrient utilization regardless of the corn type used.

Human milk vs. Infant formula digestive fate: In vitro dynamic digestion and in vivo mini-piglet models lead to similar conclusions

Infant formula (IF), the only nutritionally adequate substitute for human milk (HM), still needs to be improved to be more biomimetic with HM, including in terms of digestive fate. The latter can be explored using different digestion models. The present study aimed to compare IF and HM digestion using in vivo (mini-piglet) and in vitro (dynamic system, DIDGI®) models. Fresh mature HM was collected and compared with a standard bovine IF. In vivo, 18 Yucatan mini-piglets (24-day-old) received HM or IF and were euthanized 30 min after the last meal. The entire digestive content was collected from the stomach to the colon. In vitro, the same meals were fed to an in vitro dynamic digestion model simulating the term infant at four weeks of age. Digesta were sampled regularly in the gastric and intestinal compartments. Structure (confocal microscopy and laser light scattering) and proteolysis (SDS-PAGE for residual intact proteins, OPA for hydrolysis degree, LC-MS/MS for peptides) were investigated along digestion. The digesta microstructure differed between HM and IF in a similar way between in vitro and in vivo digestion. In vitro gastric proteolysis of caseins and α-lactalbumin was significantly slower for HM than for IF, such as for the early intestinal proteolysis degree. In vitro bioaccessibility of free AAs explained only 30 % of the true ileal digestibility of AAs. Peptide mapping of caseins differed between HM and IF along their digestion. The relative peptide mapping data over six proteins from HM and IF were highly correlated between in vitro and in vivo digestion, particularly at 80 and 120 min of in vitro gastric digestion vs. in vivo stomach data and at 20 and 40 min of in vitro intestinal digestion vs. in vivo proximal jejunum data (r = 0.7–0.9, p < 0.0001, n = 1604). 40 to 50 % of the bioactive peptides identified in vivo were also found in vitro, with a good correlation of their abundances (r = 0.5, p < 0.0001, n = 61). Overall, in vitro and in vivo digestion were in good agreement, both indicating a different digestive fate for HM and IF.

Prediction of the apparent ileal digestible amino acid contents of canola meal for broilers from crude protein content

Context Canola meal is a protein-rich feedstuff with an amino acid profile that is reasonably well balanced and has the potential to replace soybean meal in poultry diets. Aim The objective of the present study was to investigate the relationship between the crude protein content and apparent ileal digestible amino acid contents of Australian canola meals. Methods Thirteen canola meal samples, processed by expeller or solvent extractions, were collected. The digestibility assay diets were based on dextrose and contained canola meal as the sole source of protein. The proportions of dextrose and canola meal were varied in each diet to obtain ~200 g/kg crude protein. Each diet was fed to three cages of six 35-day-old broilers for 7 days. At the end of the assay, digesta from the terminal ileum was collected for digestibility determination. Key results Crude protein contents were positively correlated with amino acid contents (P &lt; 0.05 to 0.001), except that of serine (r = 0.43; P = 0.11). Significant correlations between the crude protein content and ileal digestible contents were observed for most of amino acids, with coefficients of &gt;0.80 (P &lt; 0.05 to 0.001). Low correlation coefficients were observed for lysine (r = 0.48; P = 0.11) and serine (r = 0.55; P = 0.06). The poor correlation for lysine may be reflective of reduced lysine availability during processing. Conclusions The results showed that the crude protein content of canola meal could serve as a predictor of apparent ileal digestible content of most amino acids for broiler chickens. Implications Regression equations developed in the present study could be used to predict the content of ileal digestible amino acids in canola meal by using analysed crude protein contents.

Impact of waxy protein deletions on the crystalline structure and physicochemical properties of wheat V-type resistant starch (RS5)

This study investigated the effects of waxy (Wx) protein on wheat V-type resistant starch (RS5) formation, molecular structure, and physicochemical properties. We discovered that waxy protein deletions led to a rise in B- and C-type starch granules, while reducing A-type starch granules, amylose, and slowly digestible starch contents. Further, dodecyl gallate (DG) addition significantly increased RS5 content, and molecular dynamics simulations indicated that amylose and DG can form stable complexes. Molecular docking indicated that DG could potentially aid in protecting wheat starch from digestion by human α-glucosidase. RS5 content was significantly reduced by waxy protein deletions. X-ray powder diffraction, Fourier-transform infrared spectroscopy, and laser confocal microscopy-Raman analyses revealed that waxy protein deletions decreased long-range crystalline structures and relative crystallinity and increased short-range crystalline structures，and full width at half maximum at 480 cm−1 of RS5. Pearson correlation analysis showed that RS5 content was highly correlated with its crystal structure, functional characteristics, and digestive characteristics. Principal component analysis revealed that five parameters (amylopectin, long-range crystalline structures, amylose, relative crystallinity, and RS5 content) had significant effect on the crystalline structure and functionality of RS5.

Enhanced tofu quality through calcium sulfate and transglutaminase treatment: physicochemical properties and digestibility analysis

SummaryTofu, a traditional soy‐based food, is widely consumed globally and serves as a significant source of plant protein. The quality of tofu can vary greatly depending on the coagulation process and the type of coagulants used. This study investigated the impact of a compound coagulant, consisting of transglutaminase (TGase) and calcium sulfate (CaSO4), on tofu quality, specifically focusing on pH, yield, water holding capacity (WHC), cooking loss, protein content, and in vitro digestibility. Soymilk was pre‐crosslinked with TGase for different durations (0, 1, 2, and 3 h) before the addition of CaSO4. Results indicated that TGase pre‐treatment significantly improved tofu yield and WHC, with optimal outcomes at 3 and 2 h, respectively. Cooking loss decreased with TGase treatment but increased at the 3‐h mark, suggesting over‐crosslinking. Electrophoresis revealed substantial protein crosslinking with TGase treatment, while in vitro digestion showed enhanced protein digestibility and higher peptide content in TGase‐treated samples. These findings underscore the potential of TGase treatment to enhance tofu's structural integrity and digestibility, offering valuable insights for optimising plant‐based protein processing to improve nutritional quality.

Pig True Ileal Digestible Amino Acid Contents of Individual Ingredients are Additive in Mixed Meals and Allow Accurate Predictions of Digestible Indispensable Amino Acid Score Values

BackgroundAlthough not every food protein contributes sufficient quantities of all of the indispensable amino acids (AAs) required for human health, the human diet is a mixture of foods. It is therefore important to evaluate protein quality in mixed meals. ObjectivesThe hypothesis was that the true ileal digestible AA content of mixed meals can be predicted from the amounts of digestible AA determined for individual food ingredients, allowing further prediction of the digestible indispensable amino acid score (DIAAS) for meals. MethodsFour diets contained either pea protein isolate (PPI), whey protein concentrate (WPC), or mixtures of PPI:WPC at a ratio of 25:75 (PP25) or 75:25 (PP75). Six ileal cannulated pigs were allocated to a 4 × 6 Latin Square design. Experimental diets at 10% protein and a protein-free diet were fed for 7 d with ileal digesta collection on days 6 and 7. True ileal digestibility (TID) of AA, amount of digestible AA, and DIAAS were calculated for each diet and predicted for the 2 mixed meals. ResultsPredicted and determined digestible AA contents of the mixed diets were not different. The predicted values fell within the confidence interval (95%) of the determined values. DIAAS for PPI was 61% and for WPC it was 96%. DIAAS calculated based on the predicted amounts of digestible AA for PP25 was 104% and for PP75 83%. These values were nearly identical to the determined values of 104% and 84% for PP25 and PP75, respectively. ConclusionsThe amount of digestible AA and DIAAS can be accurately predicted in mixtures of PP and WPC from the AA digestibility values for the individual ingredients.

Investigation of starch hierarchical structure in relation to physicochemical properties and digestive behavior under different high hydrostatic pressure treatment time

Changes and causal relationships in the hierarchical structure, thermal, pasting and rheological properties, as well as the digestive behavior of starch under different high hydrostatic pressure (HHP) treatment time were investigated. At 5 min, the thickness of amorphous lamellae increased (2.76 nm) and the content of B2 and B3 chains in the amorphous lamellae decreased significantly (10.78 % and 9.08 %). As the treatment time increased, the crystalline lamellae swelled and tightly arranged double helices located in the crystalline lamellae were disturbed, resulting in a decrease in the content of double helices (12.16 %) and relative crystallinity (16.96 %). Helix dissociation, crystal disruption, lamellar collapse and granule deformation were observed at 20 min. These structural changes were closely linked to variations in the physicochemical behaviors. The thermal parameters decreased gradually, accompanied by a decrease in double helix stability. The swollen crystalline lamellae provided more space for molecular stretching, thus enhancing the pasting characteristics. Regarding the digestive behavior, the swollen amorphous lamellae facilitated the invention of enzyme molecules to hydrolyze the starch at 5 min. The digestion rate coefficient and rapidly digestible starch content increased significantly until 15 min, which demonstrated that starch was more easily digested while retaining its intact granular form.

Effects of synergistic action of courgette polysaccharide and coumalic acid on pasting, rheological, and thermal properties of potato starch

AbstractThe effects of courgette polysaccharides (CP) and coumalic acid (COA) on gelatinization, rheology, thermodynamics, microstructure, freeze–thaw stability, and in vitro digestibility of potato starch (PS) were studied. The synergistic effect of CP and COA on PS was further analyzed. The results showed that peak viscosity (PV) decreased from 6649.00 to 3462.50 mPa s and 3825.00 mPa s, respectively, after CP and COA were added. Under the combined effect of the two, it will be as low as 3225.50 mPa s. Besides, trough viscosity (TV), breakdown viscosity (BV), and final viscosity (FV) had the same trend. The presence of CP and COA can significantly delay the short‐term retrogradation of PS, especially in the case of high dose of CP and low dose of COA. Rheological tests showed that all sample gels belonged to the weak gel system (tan δ &lt; 1) and pseudoplastic fluids. Meanwhile, the results of thermodynamic, Fourier transform infrared, and Raman spectroscopy exhibited that the presence of CP and COA significantly retarded the retrogradation of PS, especially at higher levels. In addition, the presence of CP and COA significantly reduced the formation of PS gel structures, especially when acting together. Furthermore, CP and COA reduced the content of rapidly digestible starch in PS and increased the content of resistant starch. Differently, CP can increase the slowly digestible starch content, whereas COA did the opposite. In the ternary composite system, CP and COA will also interact and restrict each other. Hence, the characteristics of PS can be better improved by adjusting the ratio of CP and COA. Meanwhile, the results of the study can provide potential possibilities for the application of CP and COA in food and improve the quality of PS‐related products.

Synergistic effect of pectin and the flavanols mixture on in vitro starch digestion and the corresponding mechanism

In this study, the effect and mechanism of pectin on the inhibition of in vitro starch digestion by a mixture of flavanols (rutin, quercetin, and kaempferol [R–Q–K]) were investigated, mainly from an enzymatic point of view. Results showed that the association of pectin and R–Q–K decreased the hydrolysis rate, rapidly digestible starch content, estimated glycemic index (eGI) values and hydrolysis index (HI) values, and increased the resistant starch content of different crystalline starches. Among them, cassava starch exhibited a significant decrease in terms of HI and eGI values (32.81% ± 0.65% and 10.57% ± 0.37%, respectively). Meanwhile, the lowest rate of decrease in terms of HI and eGI values was found for breadfruit starch (22.97% ± 0.39% and 7.23% ± 0.62%, respectively). The inhibitory effect of R–Q–K on α-glucosidase was attenuated by low concentrations of pectin, which was correlated to the non-covalent binding among pectin, α-glucosidase, quercetin, and kaempferol. The hydrogen bonding between pectin–R–Q–K and starch may be responsible for the ability of low concentrations of pectin and R–Q–K to synergistically delay starch digestion. Higher concentrations of pectin were noted to have the opposite trend, which was attributed to forming the binary complex of pectin–α-glucosidase. The inhibitory affinity and quenching affinity of R–Q–K for α-glucosidase were enhanced by low concentrations of pectin and attenuated by high concentrations of pectin. This study aims to provide theoretical support for the development of pectin and flavonoids in starch-based healthy foods.

Inclusion of the Cistus ladanifer L. plant and its condensed tannin extract in lamb diets - Effects on animal antioxidant status and oxidative stability of meat

This study evaluated whether the incorporation of condensed tannin (CT) extract from Cistus ladanifer in lamb diets induces the same antioxidant protection as the C. ladanifer plant. How dietary CT can enhance the antioxidant status of animals and the oxidative stability of their products was also explored. Thirty-six lambs were used to evaluate the effect of three levels of C. ladanifer CT (without CT enrichment, medium, and high level of CT) and two ways of CT supply (C. ladanifer plant or C. ladanifer CT extract) on meat lipid and colour stability, and antioxidant status of muscle, rumen, abomasum, and faeces. The presence of CT monomers in muscle and CT content in digestive contents and faeces was evaluated. Cistus ladanifer plant and CT extract did not improve the lipid stability and antioxidant status of meat, but both CT sources enhanced the meat colour stability over storage time. Condensed tannin monomers were not identified in muscle. Intake of α-tocopherol decreased with inclusion of CT sources in diets. However, muscle α-tocopherol content was not affected by diets, suggesting that CT increase the α-tocopherol availability in muscle. Both CT sources increased antioxidant activity in the digestive contents, although, in the abomasum, C. ladanifer plant resulted in higher antioxidant activity than CT extract for the same CT level in the diet. No CT were detected in the faeces and both CT sources had a minor effect on the antioxidant activity, which could indicate the CT transformation in the gastrointestinal tract.

Screening of Organic Acid Type and Dosage in Drinking Water for Young Rabbits.

Organic acids (OAs) are employed in animal feed to regulate gastrointestinal disorders and diarrhoea thanks to their ability to modulate the gastrointestinal environment and their antimicrobial capacity. However, there is not enough evidence regarding the most adequate OA and its effectiveness in rabbit farming. Therefore, the aim of this study was to screen and evaluate the response of young rabbits to six OAs, administered via drinking water, at three different concentrations (pH levels). Organic acids (acetic, ACET; formic, FOR; propionic, PROP; lactic, LAC; citric, CIT; and butyric, BUT) were tested at three concentrations (pH 3, 4, and 5). A negative control (CON; non-acidified water) was also included. We used 240 weaned rabbits (28 days old) divided into 2 batches. In each batch, animals were randomly allocated to 1 of the 19 experimental treatments and were housed in group cages of 6 animals per cage, treatment, and batch. Among the 240 rabbits, an additional cage with 6 animals was included to determine the initial physiological state of the animals. All animals were fed with commercial pelleted feed throughout the whole experiment. The duration of the study was 7 days, until 35 days of age. At 31 and 35 days of age, in each batch, three animals per day and treatment were slaughtered. The pH of the digestive contents in the fundus, antrum, duodenum, jejunum, ileum, and cecum, as well as the gastric pepsin enzyme activity, was measured. Water and feed consumption per cage and individual body weight (BW) were recorded daily. The type and dosage of OAs affected water intake. ACET 3, PROP 3, and BUT 3 reduced water intake compared to CON, negatively impacting feed intake and weight gain. FOR and CIT acids led to the highest BW and weight gain at 35 days, compared to PROP, LAC, and BUT (p < 0.05); showing ACET intermediate values. While OAs had limited effects on gastric and small intestine pH, acidified water at pH 4 and 5 lowered ileum and caecum pH (p < 0.05) compared to pH 3. Acidified water at pH 4 showed the highest (p < 0.05) pepsin activity compared to pH 3 and pH 5. Considering the limited sample size and short-term assessment period of our screening test, the OAs with the highest potential for use in post-weaning rabbits were FOR, ACET, and CIT at pH 4. The selected combinations did not exhibit any early adverse effects in young rabbits. These results should be further confirmed in a broader population of animals. It would also be advisable to extend the application of OAs over longer periods to evaluate their effects throughout the entire growing period of rabbits.

Replacement of Native with Malted Triticale (x Triticosecale Wittmack) Flour in Dry Pasta: Technological and Nutritional Implications.

The use of native and malted triticale (MT) flour in dry pasta has been limited despite the potential of triticale in cereal-based food production. In this study, triticale-based dry spaghetti with increasing levels of substitution (0, 25, 50, and 75 g/100 g w/w) of MT flour were formulated and analyzed. Samples were analyzed for technological and nutritional traits, including the in vitro starch and protein digestions. The gradual substitution of native triticale flour with MT increased (p < 0.05) the total dietary fiber content, whereas total starch decreased (p < 0.05). Adding MT flour increased the cooking loss and the stickiness of cooked pasta (p < 0.05). Using MT flour modulated the in vitro starch digestion, lowering the slowly digestible and resistant starch contents. The in vitro protein digestibility was positively affected using MT at the highest substitution level. Overall, MT could be used to formulate dry pasta products being the substitution to native triticale up to 50 g/100 g, a good compromise between nutritional quality and technological characteristics.

Germination-Induced Enhancement of Brown Rice Noodle Nutritional Profile and Gut Microbiota Modulation.

This study explored how germination influences the starch digestion and intestinal fermentation characteristics of brown rice noodle. The study began with in vitro starch digestion tests to assess how germination affects starch digestibility in brown rice noodles, revealing an increase in rapidly digestible starch content and a decrease in resistant starch content. Subsequently, an in vitro human fecal fermentation model was used to simulate the human intestinal environment, showing that germination altered pH levels and the production of short-chain fatty acids, particularly by increasing propionate while decreasing acetate and butyrate. Additionally, the study noted a decrease in gut microbiota diversity following fermentation, accompanied by an increase in Megamonas growth and a decrease in Bacteroides and Bifidobacterium. In conclusion, these findings suggest that germination could enhance the nutritional value and intestinal probiotic properties of brown rice noodles. This research contributes valuable insights into the role of germination in improving the nutritional properties of rice-based products and provides a foundation for further exploration into the development of health-promoting rice noodles.

In situ starch and water modification using atmospheric plasma: Structure, functionality and in vitro digestibility

Starch modification has become necessary to develop functional foods. Sustainable technologies like plasma-activated water (PAW) have been combined with hydrothermal treatments; however, the scaling-up process is challenging. Therefore, a simultaneous treatment of starch and water in a plasma reactor and a 24 h soaking of starch-water after the treatment were compared. The effect of the treatments on the structural, functional, and digestibility properties of starches (normal (NS), waxy (WS), and high amylose (HAS)) with different amylose/amylopectin content was assessed. The results show that simultaneous treatment mainly affected the water properties. Nevertheless, the contact time (24 h) after treatment between starch and water promoted the alteration of amylose chains, branching amylopectin molecules and hydrated crystals of HAS, increasing its rapidly (RDS) and slowly (SDS) digestible starch content. Meanwhile, in NS, the contact time favored the high re-engagement of amylose-amylopectin chains inside starch granules, significantly improving the resistant starch (RS) fraction from 31 % to 75 %.

Modifications of the Structural, Nutritional, and Allergenic Properties of Atlantic Cod Induced by Novel Thermal Glycation Treatments.

This study aimed to assess the effect of novel thermal glycation, utilizing microwave processing (100-150 °C) combined with sugars (glucose and lactose), on the in vitro protein digestibility, peptides, secondary structures, microstructures, and allergenic properties of Atlantic cod. The research demonstrated that microwave heating at 150 °C with glucose significantly reduced cod allergenicity by up to 16.16%, while also enhancing in vitro protein digestibility to 69.05%. Glucose was found to be more effective than lactose in conjunction with microwave heating in reducing the allergenicity of Atlantic cod. Moreover, treatments conducted at 150 °C were more effective in increasing in vitro protein digestibility and peptide content compared to those at 100 °C. This study revealed that the novel processing technique of thermal glycation effectively reduced the allergenicity of Atlantic cod. It also offered fresh insights into the potential benefits of combining microwave heating with sugars.

Digestible indispensable amino acid score (DIAAS): 10 years on.

The objective of the review is to revisit the findings of the 2011 Food and Agriculture Organization of the United Nations (FAO) Expert Consultation on Dietary Protein Quality Evaluation in Human Nutrition, and to report on progress on uptake of the findings. It is evident that since 2011 there has been a concerted research effort to enhance an understanding of the protein quality of foods. The validity of the growing pig ileal protein digestibility assay has been confirmed and numerous studies reported using the growing pig as a model to give true ileal amino acid digestibility values for foods as consumed by humans. This has allowed for the determination of digestible indispensable amino acid scores (DIAAS) for a range of foods. A new non-invasive true ileal amino acid digestibility assay in humans which can be applied in different physiological states, called the dual-isotope assay, has been developed and applied to determine the DIAAS values of foods. It is concluded that DIAAS is currently the most accurate score for routinely assessing the protein quality rating of single source proteins. In the future, the accuracy of DIAAS can be enhanced by improved information on: the ideal dietary amino acid balance including the ideal dispensable to indispensable amino acid ratio; dietary indispensable amino acid requirements; effects of processing on ileal amino acid digestibility and lysine bioavailability. There is a need to develop rapid, inexpensive in vitro digestibility assays. Conceptual issues relating DIAAS to food regulatory claims, and to holistic indices of food nutritional and health status are discussed. The first recommendation of the 2011 Consultation regarding treating each indispensable amino acid as an individual nutrient has received little attention. Consideration should be given to providing food label information on the digestible contents of specific indispensable amino acids.

Insights into the diet and feeding behavior of immature polar cod (Boreogadus saida) from the under-ice habitat of the central Arctic Ocean.

Polar cod (Boreogadus saida) is an endemic key species of the Arctic Ocean ecosystem. The ecology of this forage fish is well studied in Arctic shelf habitats where a large part of its population lives. However, knowledge about its ecology in the central Arctic Ocean (CAO), including its use of the sea-ice habitat, is hitherto very limited. To increase this knowledge, samples were collected at the under-ice surface during several expeditions to the CAO between 2012 and 2020, including the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The diet of immature B. saida and the taxonomic composition of their potential prey were analysed, showing that both sympagic and pelagic species were important prey items. Stomach contents included expected prey such as copepods and amphipods. Surprisingly, more rarely observed prey such as appendicularians, chaetognaths, and euphausiids were also found to be important. Comparisons of the fish stomach contents with prey distribution data suggests opportunistic feeding. However, relative prey density and catchability are important factors that determine which type of prey is ingested. Prey that ensures limited energy expenditure on hunting and feeding is often found in the stomach contents even though it is not the dominant species present in the environment. To investigate the importance of prey quality and quantity for the growth of B. saida in this area, we measured energy content of dominant prey species and used a bioenergetic model to quantify the effect of variations in diet on growth rate potential. The modeling results suggest that diet variability was largely explained by stomach fullness and, to a lesser degree, the energetic content of the prey. Our results suggest that under climate change, immature B. saida may be at least equally sensitive to a loss in the number of efficiently hunted prey than to a reduction in the prey's energy content. Consequences for the growth and survival of B. saida will not depend on prey presence alone, but also on prey catchability, digestibility, and energy content.

Dietary protein level influences growth, adult emergence, and susceptibility to bacterial infection in Hermetia illucens L. (Diptera: Stratiomyidae) larvae

Abstract The larvae of the black soldier fly (BSFL), Hermetia illucens L. (Diptera: Stratiomyidae), are grown on diverse residual organic matter that differ in their protein content and contain a plethora of microorganisms. The effect of dietary protein level on the interaction of BSFL with entomopathogenic bacteria remains unexplored. In this study, we investigated the role of dietary protein level on BSFL growth, uric acid accumulation, and adult emergence and the outcome of the host-pathogen interaction between BSFL and the Gram-negative bacterium Pseudomonas protegens Pf-5. We formulated three experimental diets in which digestible carbohydrate content was maintained at 50% of dry matter (DM), and crude protein was included at either 10% (low protein), 22.5% (medium protein), or 35% (high protein) DM, respectively. The influence of these diets on larval biomass, accumulation of uric acid in the larval hindgut, and subsequent adult emergence were recorded. In addition, the survival of BSFL fed on these diets was monitored for 64 hours after injection with an LD50 dose (1 μl of 2.5 × 103 CFU/ml) of P. protegens Pf-5. The biomass of 5-day-old larvae grown on a low-protein diet was higher than that of larvae grown on a high-protein diet. However, no such difference in biomass was observed in 8-day-old larvae. The amount of uric acid in the hindgut of larvae fed on high protein was three-fold and two-fold higher than larvae fed on low- and medium-protein diets, respectively. Adult emergence on a high-protein diet was significantly reduced and delayed compared to low- and medium-protein diets. BSFL fed a high-protein diet displayed significantly lower survival after infection with P. protegens Pf-5 than those fed a low-protein diet. Overall, feeding a high-protein diet reduced adult emergence and combined with infection with a Gram-negative bacterium survival of BSF larvae was strongly reduced.

Effects of Mineral Elements and Annealing on the Physicochemical Properties of Native Potato Starch

Native potato starch is an excellent carrier of minerals due to its inherent ion exchange capacity. Mineral enrichment not only changes the nutritional value but also influences starch pasting and swelling properties. Hydrothermal treatments like annealing constitute a straightforward and green way to tune functional properties. Here, novel combinations of mineral enrichment and annealing were studied. Ion exchange was readily achieved by suspending starch in a salt solution at room temperature over 3 h and confirmed by ICP-OES. Annealing at 50 °C for 24 h using demineralized water or salt solutions strongly affected pasting, thermal, and swelling properties. The obtained XRD and DSC results support a more ordered structure with relative crystallinity increasing from initially 41.7% to 44.4% and gelatinization onset temperature increasing from 60.39 to 65.94 J/g. Solid-state NMR spectroscopy revealed no detectable changes after annealing. Total digestible starch content decreased after annealing from 8.89 to 7.86 g/100 g. During both ion exchange at room temperature and annealing, monovalent cations promoted swelling and peak viscosity, and divalent cations suppressed peak viscosity through ionic crosslinking. The presented combination allows fine-tuning of pasting behavior, potentially enabling requirements of respective food applications to be met while offering an alternative to chemically modified starches.