Evaluation Of Protein Quality Research Articles

Production of cultured fat with peanut wire-drawing protein scaffold and quality evaluation based on texture and volatile compounds analysis

Cultured meat is an emergent technology that cultivates cells in three-dimensional scaffolds to generate tissue for consumption. Fat makes an important contribution to the flavor and texture of traditional meat, but there are few reports on cultured fat. Here, we demonstrated the construction of cultured fat by inoculating porcine adipose-derived mesenchymal stem cell (ADSC) on peanut wire-drawing protein (PWP) scaffolds. First, we demonstrated that basic fibroblast growth factor (bFGF) promoted cell proliferation and maintained adipogenic differentiation ability. Then, we generated cultured fat and found that cultured fat decreased the texture of PWP scaffolds. Moreover, 43 volatile compounds were detected by headspace gas chromatography-ion mobility spectrometry (GC-IMS), of which 17 volatile compounds showed no significant differences between cultured fat and porcine subcutaneous adipose tissue (pSAT), which indicated that cultured fat and pSAT had certain similarities. Collectively, this research has great promise for improving the quality of cultured meat.

Bioactive Compounds, Amino Acid Content/Score of Composite Wheat, African Walnut, Moringa Biscuits

Moringa and African walnut seeds were processed into flour and evaluated for tannin, total phenol and anti-oxidant activity. Different formulations of wheat, African walnut and Moringa seed composite flour (A: WHF 100%: AWF 0;MSF 0, B= WHF 77.5%:AWF 20%: MSF 2.5%, C=WHF 75%: AWF 20%: MSF 5.0%, D= WHF 72.5%: AWF 20%: MSF 7.5%. E = WHF 70%: AWF 20%: MSF 10%, F = WHF 90%: AWF 0 : MSF 10%, G = WHF 80% : AWF 20% : MSF 0 ) were used in the production of biscuits. The Amino acid content of the prepared biscuits were determined and the Amino acid score using Hens egg and FAO standard to evaluate protein quality. Results reveal that Tannin and Total phenol content of African walnut flour was significantly higher with values 49.82mg/100g and 54.90mg/100g respectively, with Moringa seed flour having an anti-oxidant activity of 60.55%. Amino acid content of the biscuits showed that glutamic acid was higher in all the samples ranging from 10.96 – 12.33g/100g. Amino acid score results indicate that the amino acid content of the composite biscuits were higher than the FAO standards for adults above 18years.

Using the dual isotope method to assess cecal amino acid absorption of goat whey protein in rats, a pilot study.

Measurement of ileal amino acids (AA) bioavailability is recommended to evaluate protein quality. A dual isotope tracer method, based on plasma isotopic enrichment ratios, has been proposed to determine true digestibility in humans. In a pilot study, we aimed to evaluate whether this method could be implemented in rats to determine AA bioavailability based on isotopic enrichment ratios measured in cecal digesta or plasma samples. Goat milk proteins were intrinsically labeled with 15N and 2H. Wistar rats were fed a meal containing the doubly labeled goat whey proteins and a tracer dose of 13C-spirulina. Blood samples were collected 0, 1h and 3h after meal ingestion from the tail vein. The rats were euthanized 4h (n = 6) or 6h (n = 6) after meal to collect plasma and intestinal contents. True orocecal protein digestibility and AA bioavailability were assessed by means of 15N and 2H enrichment in cecum content and compared with absorption indexes determined at the plasma or cecum level using isotopic ratios. Plasma kinetics of isotopic enrichment could not be completed due to the limited quantity of plasma obtained with sequential blood collection. However, the absorption indexes determined from cecal 15N or 2H/13C ratios gave coherent values with true orocecal AA bioavailability. This dual isotope approach with measurements of isotopic ratios in digestive content could be an interesting strategy to determine true AA bioavailability in ileal digesta of rats.

Evaluation of patatin content in proteins of potato genotypes grown in Latvia

Abstract Potato proteins contains essential amino acids in considerably high concentration, therefore potatoes are considered to be one of the most valuable plant origin food for human consumption. Patatin forms one of the largest group of potato proteins with high potential to be used in food industry as a novel food. This study has been performed to approbate patatin determination method for evaluation of protein quality of potato genotypes, as well as evaluate patatin relative abundance (PRA) for breeding programmes to create in the future potato cultivars with higher value and potential to develop new products. The evaluation of patatin was performed in following steps– extraction proteins from potato, determination of patatin concentration and calculation of its relative abundance in proteins. Separation of patatin from potato tubers was made using extraction by SDS extraction buffer and determination of patatin in organically and conventionally (with differnt N suply) grown samples of 20 potato genotypes. The results of one-year study showed that patatin relative abundance of different cultivars varied from 1.65% to 50.2% and it was significantly different among genotypes. The nitrogen content of soil and maturity type of potato did not affect PRA significantly. Results provide impetus for further research.

Comparing nutritional and digestibility aspects of sustainable proteins using the INFOGEST digestion protocol

• Most of the alternative proteins have a good protein hydrolysis and digestibility. • An in vitro DIAAS calculation method based on INFOGEST protocol was developed. • Whey, potato, blood plasma and yeast protein concentrates have a high IVDIAAS. • Food products with complex matrix and low protein content require further optimisation of the method. We studied several sustainable alternative protein concentrates and a whey protein concentrate as reference, to determine their protein composition, digestibility and quality using the harmonized INFOGEST static protocol. The proteins concentrates were analyzed to determine their conversion factor, degree of hydrolysis, true ileal digestibility, in vitro digestible indispensable amino acid score (IVDIAAS) and total absorbable amino acids and total essential amino acids. The results revealed that whey, blood plasma concentrate and yeast protein concentrate have a high mean true ileal indispensable amino acid in vitro digestibility (91.1–85.8%), closely followed by corn, pea, potato and proteins derived from lesser meal worms (ranging between 82.5 and 77.9%). Mycoprotein gave a much lower score in the mass balance, so that its other results could not be interpreted as being reliable. Whey, potato, blood plasma and yeast protein concentrates ranked highest in IVDIAAS (between 119 and 97.2), followed by lesser meal worm and pea (between 73.8 and 57.8) with corn protein concentrate having the lowest IVDIAAS due to underrepresentation of lysine. The method and data presented in this paper can form a start for further applying the INFOGEST in vitro digestion protocol to evaluate protein quality.

Pigs (Sus Scrofa) in Biomedical Research.

Much of biomedical oriented research is conducted with animal models. Over the years, rodents (primarily rats and mice) have emerged as the preferred species for basic biochemistry, cell biology, physiology and nutrition studies. In the past, dogs have been used for the evaluation of dietary protein quality and other aspects of animal nitrogen metabolism and physiology, cardiovascular and endocrine research. At an increasing rate, pigs have also been used as a model species in biomedical research. Pigs are readily available in various mature sizes and genotypic/phenotypic traits, and there are many anatomic, nutritional and physiologic similarities between human beings and pigs. Many notable reviews summarizing the role of pigs in biomedical studies have already been published and these are cited below. The present review focuses on characteristics that make pigs an excellent biomedical animal model in particular in obesity, diabetes and cardiovascular research. To procure an animal model for obesity, irrespective of species used, these animals must be fed a dense caloric diet (high fat) to achieve an experimental working model within a reasonable period. This review also focuses on a putative role of gastrointestinal microbiota in obesity as obese animals exhibit a shift in the distribution of gastrointestinal microbial phyla from lean animals. But to date such results have not pinpointed a treatable cause for obesity. Sometimes, the choice of sampling sites for microbial assessment in many reports can be questioned as the microbial content and phyla distribution in easily collected fecal samples may differ from those obtained directly from the small intestine and upper colon. While pigs are still utilized in many countries for medical surgery practice, this has been discontinued in US medical schools.

Nutritional, Biochemical and Haematological Indices of White Albino Rats Fed Complementary Diets Developed from Selected Cereals and Legumes

Background: Childhood malnutrition is a common public health problem in Ethiopia. This animal study aims to evaluate the haematological, biochemical, and nutritional indices of weanling albino rats fed on complementary diets developed from selected cereals and legumes. Methods: The nutritional qualities of the formulated blends were assessed biologically by feeding white albino rats in order to determine feed intake, the growth rate, protein quality parameters, biochemical and haematological properties. The commercial weaning diet (cerifam) and casein were used as control diets. On the 28th day, blood samples were collected from three randomly selected rats by decapitation. Full blood count analysis was carried out using the Automated Haematologic Analyzer to determine haematological parameters. All the biochemical parameters were determined using Mindray diagnostic kits. Results and Discussion: The food intake pattern showed that animals placed on diet 3, diet 4, casein, and cerifam consumed more food than those fed on diet 1, diet 2, and diet 7. The mean growth rate of animals fed on diet 3 and diet 4 was significantly (p<0.05) higher than those placed on diet 1, diet 2, and diet 7 but similar to those fed with commercial diet and casein. The protein quality evaluation of the diets showed that the protein efficiency ratio ranged from 1.20 to 2.43 while the biological value was in the range of 54.53 to 69.48%. The net protein utilization and true digestibility were 65.62 to 70.21% and 59.01 to 64.01%, respectively. Serum total protein, albumin, and globulin levels in rats given diet 3 and diet 4 were comparable to the controls and within the normal range. Comparatively, the creatinine and urea levels of rats fed on the control and formulated diets were within the normal range. The serum alanine aminotransferase values of rats fed on the control and formulated diets ranged from 22.03 IU/L in diet 2 to 37.76 IU/L in diet 4 and were not significantly different from each other. In this study, the packed cell volume and haemoglobin values of the control and formulated diets were within the recommended range. Evidently, diet 3 and diet 4 gave the best growth performance after the feeding trials. Conclusion: The haematological and biochemical indices indicate that these diets can support effective growth and development in rats, and consumption of these diets has no detrimental effects on the liver and renal function.

Extruded breakfast meal from malted finger millet (Eleusine coracana) and watermelon (Citrullus lanatus) seed flour: in-vivo nutritional qualities study

BackgroundThe study aimed at evaluating the in-vivo nutritional qualities of extruded breakfast meal produced from flour blends of malted finger millet and watermelon seed.ResultsThe proximate compositions of the flour blends revealed that there was progressive increase in protein (12.83–15.14) %, with increase in the watermelon substitution. The protein quality evaluation of the extrudate showed that the protein efficiency ratio ranged from 0.64 to 89.75, while the biological values were between (87.82–89.75)%. The relative organs weight of rats fed with extruded breakfast meal showed that, the weights of the kidney and liver of rats fed with extruded breakfast meal were significantly lower compared with rats fed with goldenmorn. The hematological indices showed that the packed cell volume and the red blood cell counts of rats fed with the formulated diets were significantly lower compared with those fed with goldenmorn but significantly higher than rats fed with basal. Meanwhile, the values of the white blood cells count for the formulated diet shows no significant difference compared with rats fed with goldenmorn.ConclusionsEvidently, the growth performance of the rats fed with the extruded breakfast meal revealed that the formulated diets promote growth status of the animals with relatively low effect on organs of experimental rat used in this study. Hence, formulated diet may serve as alternative to expensive commercial breakfast meal.

Values for Digestible Indispensable Amino Acid Score (DIAAS) Determined in Pigs Are Greater for Milk Than for Breakfast Cereals, but DIAAS Values for Individual Ingredients Are Additive in Combined Meals

BackgroundBreakfast cereals contain low-quality proteins and are often consumed with milk. The digestible indispensable amino acid score (DIAAS) has been used to evaluate protein quality, but it is not known if DIAAS obtained in individual foods is additive in combined meals. ObjectivesThe following hypotheses were tested: amino acids (AAs) in milk complement AAs in breakfast cereals to provide a balanced meal, and DIAAS in individual foods is additive in combined meals. MethodsSix ileal cannulated gilts [body weight mean: 55.6 ± 3.7 (SD) kg] were allotted to a 6 × 6 Latin square with six 7-d periods. Ileal digesta were collected for 9 h on days 6 and 7 of each period. Three diets contained a breakfast cereal (i.e., cornflakes or quick oats) or dry milk as the sole source of AAs. Two additional diets contained a combination of dry milk and cornflakes or quick oats. A nitrogen-free diet was also used, and DIAAS was calculated for cornflakes, quick oats, dry milk, and the 2 combined meals for children aged 6 to 36 mo and individuals older than 36 mo through adulthood. For the combined meals, DIAAS was also predicted from the individual ingredient DIAAS. ResultsDry milk had greater (P < 0.05) DIAAS (123 and 144) than quick oats (57 and 67), but cornflakes had less (P < 0.05) DIAAS (16 and 19) than the other ingredients. Both breakfast cereal–dry milk meals had DIAAS close to or greater than 100 for children aged 6 mo to 3 y and for older children, adolescents, and adults, but there were no differences between measured and predicted DIAAS. ConclusionsThe combination of milk and breakfast cereals results in a meal that is balanced in indispensable AAs for humans, and DIAAS obtained from individual ingredients is additive in mixed meals.

Limitations with the Digestible Indispensable Amino Acid Score (DIAAS) with Special Attention to Plant-Based Diets: a Review.

This review describes several limitations of the Digestible Indispensable Amino Acid Score (DIAAS) with a focus on its application to plant-based dietary patterns. Evaluating protein quality in terms of digestibility is paramount to support and optimize the health and well-being of human populations in situations where food insecurity and protein energy malnutrition are widespread. The Food and Agriculture Organization (FAO) of the United Nations has endorsed the DIAAS to replace the previously recommended Protein Digestibility Corrected Amino Acid Score (PDCAAS) for protein quality assessment. While multiple strengths characterize the DIAAS, substantial limitations remain, many of which are accentuated in the context of a plant-based dietary pattern. Some of these limitations include a failure to translate differences in nitrogen-to-protein conversion factors between plant- and animal-based foods, limited representation of commonly consumed plant-based foods within the scoring framework, inadequate recognition of the increased digestibility of commonly consumed heat-treated and processed plant-based foods, its formulation centered on fast-growing animal models rather than humans, and a focus on individual isolated foods vs the food matrix. The DIAAS is also increasingly being used out of context where its application could produce erroneous results such as exercise settings. When investigating protein quality, particularly in a plant-based dietary context, the DIAAS should ideally be avoided.

Evaluation of Protein Quality of Rice Gluten Meal and Rice Distillers Dried Grains with Solubles in Terms of Net Protein Utilization and Gross Protein Value for Broilers (IBL-80)

Evaluation of Protein Quality of Rice Gluten Meal and Rice Distillers Dried Grains with Solubles in Terms of Net Protein Utilization and Gross Protein Value for Broilers (IBL-80)

Protein Quality Evaluation of Raw and Processed Seeds of Cadaba farinosa Forssk and Growth Performance of Albino Rats Fed with the Products

Cadaba farinosa Forssk is a wild shrub whose seeds are eaten as a famine food in North Eastern Nigeria when there is poor harvest of conventional crops. This research was carried out in order to evaluate the protein quality of the seeds and to carry out the growth performance of experimental animals fed on seeds processed by different methods. The processed methods include cooking, cooking with the addition of potash, fermentation and sprouting. PTH-Amino acid analyzer was used to determine the amino acid profile and milk reference protein was used for scoring the essential amino acids. The products were fed to weaning albino rats for 28 days growth performance studies. The determination of nitrogen content of the feed, faeces, urine and the carcass of the animals were carried out by Kjeldahl method. Protein quality evaluation of the processed products was carried out by calculating the Biological Value (BV), Protein Efficiency Ratio (PER), Net Protein Utilization (NPU) and The Protein Digestibility-Corrected Amino Acids Score (PDCAAS). Results of Amino acid analysis showed that the sample cooked with addition of potash contain higher levels of amino acids. Glutamic acid was found to the most abundant amino acid with a value of 11.96 g/ 100 g and 13.96 g/ 100 g in the sprouted and raw seeds respectively. Chemical score of amino acids revealed higher score for protein of seeds cooked with addition of potash except tryptophan which was 219.29% for seeds cooked without potash. The highest PDCAAS (49.84%) was found in the diet cooked with potash, however, it showed lower biological value (95%) and protein efficiency ratio (0.32). The group fed with sprouted diet showed significant increase (P=.05) in body weight (52.13%). Though cooking with addition of potash showed higher distribution of amino acids, but sprouting and fermentation were more promising in terms of promoting the growth of the experimental animals.

Production and Quality Evaluation of Water Yam: Sesame Based Snack (Akuto)

Akuto is an old delicacy in Benue State. This nutritious delicacy has gone into extinction due to the emergence of new food products. An attempt has been made to convert this delicacy into high protein snacks using water yam tuber and sesame seeds. Boiled water yam tuber and toasted sesame seeds were blended in different proportions (A-100:0, B-90:10, C-80:20, D-70:30, E-60:40, F-50:50) to produce Akuto snack. Products were analyzed for proximate composition, sensory and protein quality evaluation using rat assay. Results indicated that Sample A (100% water yam) has highest acceptability from the sensory evaluation. There was significant increase in protein content with the inclusion of toasted sesame seed with values ranging from 5.06 to 20.08%. Protein Efficiency ratio (PER) also increased with sesame supplementation and group F had highest value 3.03. Biological Value (BV) and Net Protein Utilisation (NPU) was highest in reference diet group (G) 96.76% and 93.00% followed by test diet group (F) 77.85% and 55.91% respectively.

Determination of True Ileal Amino Acid Digestibility in the Growing Pig for Calculation of Digestible Indispensable Amino Acid Score (DIAAS)

Digestible indispensable amino acid score (DIAAS) has been recommended by the FAO for the evaluation of protein quality in human foods, but the application of DIAAS is currently limited because of a lack of published data on the true ileal amino acid (AA) digestibility of AAs in foods. The importance of DIAAS is highlighted. To calculate DIAAS, it is necessary to determine the true ileal AA digestibility of human foods using the growing pig as an animal model for the human based on previous FAO recommendations. A method is described in detail in Supplemental Methods to determine the true ileal AA digestibility of foods for humans using the pig as a model for the adult human. Adoption of the method will enable consistency in the development of databases on predicted true ileal AA digestibility in human foods for the calculation of DIAAS.

Protein Quality evaluation of Goat and Cow Milk Infant Formula in rats

Infant formula products are predominantly manufactured using cow milk protein; goat milk also provides a suitable protein source. Due to the differences in the composition of proteins between human milk, cow milk, and goat milk, infant formula has been designed to be closer to human milk as much as possible. In this study, goat and cow milk infant formulas were prepared by adding α-lactalbumin and it was directly compared to commercial infant formula protein digestion using growing rats. The nutritional value of these formulated diets was evaluated by estimating their proximate composition, the protein efficiency ratio (PER), corrected protein efficiency ratio (CPER), net protein ratio (NPR). The composition of the formulated diets indicated that satisfied legal nutrient content regulation and are within the range of recommended standards. The PER, CPER and NPR of formulated diets did not significantly (P>0.05) different and much closed to those of casein. It was observed no significant difference due to milk type in the quality of protein. The protein quality of the formulated goat and cow infant formula were well comparable with those of commercial infant formula, the common infant diet over the world.

Blood 15N:13C Enrichment Ratios Are Proportional to the Ingested Quantity of Protein with the Dual-Tracer Approach for Determining Amino Acid Bioavailability in Humans

ABSTRACTBackgroundAssessment of amino acid bioavailability is of key importance for the evaluation of protein quality; however, measuring ileal digestibility of dietary proteins in humans is challenging. Therefore, a less-invasive dual stable isotope tracer approach was developed.ObjectiveWe aimed to test the assumption that the 15N:13C enrichment ratio in the blood increases proportionally to the quantity ingested by applying different quantities of 15N test protein.MethodsIn a crossover design, 10 healthy adults were given a semi-liquid mixed meal containing 25 g (low protein) or 50 g (high protein) of 15N-labeled milk protein concentrate simultaneous with 0.4 g of highly 13C–enriched spirulina. The meal was distributed over multiple small portions, frequently provided every 20 min during a period of 160 min. For several amino acids, the blood 15N- related to 13C-isotopic enrichment ratio was determined at t = 0, 30, 60, 90, 120, 180, 240, 300, and 360 min and differences between the 2 meals were compared using paired analyses.ResultsNo differences in 13C AUC for each of the measured amino acids in serum was observed when ingesting a low- or high-protein meal, whereas 15N AUC of amino acids was ∼2 times larger on the high-protein meal (P < 0.001). Doubling the intake of 15N-labeled amino acids increased the 15N:13C ratio by a factor of 2.04 ± 0.445 for lysine and a factor between 1.8 and 2.2 for other analyzed amino acids, with only phenylalanine (2.26), methionine (2.48), and tryptophan (3.02) outside this range.ConclusionsThe amino acid 15N:13C enrichment ratio in the peripheral circulation increased proportionally to the quantity of 15N-labeled milk protein ingested, especially for lysine, in healthy adults. However, when using 15N-labeled protein, correction for, e.g., α-carbon 15N atom transamination is advised for determination of bioavailability of individual amino acids. This trial was registered at www.clinicaltrials.gov as NCT02966704.

Protein quality and safety evaluation of sarcoplasmic protein derived from silver carp (Hypophthalmichthys molitrix) using a rat model.

Consisting of 25 to 30% of protein in carp, water-soluble sarcoplasmic proteins lost in wash water, have been recovered and freeze-dried into a protein-rich powder. Study objectives were to evaluate protein quality and safety of a silver carp sarcoplasm derived protein powder (CSP) compared to commercial protein supplements, casein, and whey. In vivo protein quality assessment of CSP showed a lower (P<0.05) protein digestibility corrected amino acid score compared to the commercial protein sources. Despite greater (P<0.05) fecal amino acid excretion in casein-fed rats, there were no significant differences in liver and muscle amino acid profiles. All low (10%kcal) protein diets supported growth with the normal range. However, whey protein supplementation resulted in greater (P<0.05) adiposity. CSP, casein, or whey-fed rats showed no differences in major organ weights, renal damage biomarkers, or bone indices. Collectively, results indicated CSP was safe with protein quality comparable to casein. PRACTICAL APPLICATION: As much as 40 percent of protein in fish can be lost due to sarcoplasmic protein solubilization in processing wash water. Silver carp sarcoplasm protein powder may have similar commercial potential as a sustainable and nutritious alternative to whey and casein proteins. This project aimed to verify the protein quality and safety of this economical protein source.

A Comparison of Protein Digestibility Corrected Amino Acid Score with Digestible Indispensable Amino Acid Score to Evaluate Protein Quality of Raw and Roasted Pistachio Nuts

Abstract Objectives The objectives of this research were to determine the protein digestibility corrected amino acid score (PDCAAS) and the digestible indispensable amino acid score (DIAAS) for raw and roasted American pistachio nuts in growing pigs, and to assess the effect of roasting on these measures of protein quality. Methods Twelve ileal cannulated barrows (body weight: 60.9 ± 3.2 kg) were randomly allotted to a 2-period switch-back design with 3 diets and 4 replicate pigs per period. Roasted pistachio nuts and raw pistachio nuts (American cultivated pistachio nuts) were each added to a single diet as the only protein source, and the third diet was a nitrogen-free diet that was used to measure basal endogenous losses of AA. Experimental periods were 9 d with the initial 5 d for adaptation to the diets. On d 6 and 7, fecal samples were collected, and on d 8 and 9, ileal digesta samples were collected for 9 h each day. The PDCAAS and DIAAS were calculated according to the Food and Agriculture Organization. Results The standardized ileal digestibility (SID) of all indispensable AA, except Arg and Phe, was less (P &amp;lt; 0.05) in roasted than in raw pistachio nuts. Raw pistachio nuts had a PDCAAS of 73 and roasted pistachio nuts had a PDCAAS of 81, calculated for children 2 to 5 yr, and the first limiting AA when compared to human requirements was Thr for both pistachio nuts. The DIAAS calculated for children older than 3 years, adolescents, and adults was 86 and 83 for raw and roasted pistachio nuts, respectively. The limiting AA in both raw and roasted pistachio nuts that determined the DIAAS for this age group was Lys. Conclusions Results of this research illustrate that raw and roasted pistachio nuts can be considered a good quality protein source with DIAAS greater than 75, however, heating conditions associated with roasting may decrease the digestibility of AA in pistachio nuts. Funding Sources The U.S. Department of Agriculture's (USDA) Agricultural Marketing Service. Product was supplied by the American Pistachio Growers.

Protein Quality Assessment of Follow-up Formula for Young Children and Ready-to-Use Therapeutic Foods: Recommendations by the FAO Expert Working Group in 2017

The FAO of the UN convened an Expert Working Group meeting to provide recommendations related to protein quality evaluation of Follow-up Formula for Young Children (FUF-YC) and Ready-to-Use Therapeutic Foods (RUTFs). The protein and amino acid (AA) scoring patterns for the target age groups were defined and recommendations provided on the use of currently available protein and indispensable AA digestibility data. For FUF-YC, an age category of 1-2.9 y was identified, and a matching protein requirement of 0.86g · kg-1 · d-1 with corresponding AA requirements were recommended. For RUTF, the protein requirement recommended was 2.82g · kg-1 · d-1, to achieve a catch-up weight gain of 10g · kg-1 · d-1 in children recovering from severe acute malnutrition. The AA requirements were factorially derived based on the adult protein requirement for maintenance and tissue AA composition. A flowchart was proposed for the best available methods to estimate digestibility coefficients (of either protein or AAs), in the following order: human, growing pig, and rat true ileal AA digestibility values. Where this is not possible, fecal protein digestibility values should be used. The Expert Working Group recommends the use of the Protein Digestibility Corrected Amino Acid Score (PDCAAS), with existing protein digestibility values, or the Digestible Indispensable Amino Acid Score provided that individual AA digestibility values are available for protein quality evaluation using the latter score. The Group also recommends the use of ileal digestibility of protein or of AAs for plant-based protein sources, recognizing the possible effects of antinutritional factors and impaired gut function. A PDCAAS score of ≥90% can be considered adequate for these formulations, whereas with a score <90%, the quantity of protein should be increased to meet the requirements. Regardless of the protein quality score, the ability of formulations to support growth in the target population should be evaluated. Future research recommendations are also proposed based on the knowledge gaps identified.

Determination of Dietary Amino Acid Digestibility in Humans

Dietary amino acid digestibility is a fundamental measure of importance in protein quality evaluation. Determining amino acid digestibility in humans, as the disappearance of an amino acid across the total digestive tract, has been discredited. Extensive cecal and colonic microbial metabolism renders fecal estimates of amino acids misleading. True ileal amino acid digestibility determined at the end of the small intestine predicts amino acid uptake more accurately. Given that ileal digestibility determination cannot be undertaken routinely in humans, a pig-based assay has been developed and validated. The growing pig values for digestibility, however, relate to healthy adult humans and there is a need to be able to determine amino acid digestibility for humans with specific physiological states. To this end, isotope-based methods for determining dietary amino acid digestibility indirectly show promise but remain to be fully validated.