Some Insect Species Are Good-Quality Protein Sources for Children and Adults: Digestible Indispensable Amino Acid Score (DIAAS) Determined in Growing Pigs

Smart proteins as a new paradigm for meeting dietary protein sufficiency of India: a critical review on the safety and sustainability of different protein sources

India, a global leader in agriculture, faces sustainability challenges in feeding its population. Although primarily a vegetarian population, the consumption of animal derived proteins has tremendously increased in recent years. Excessive dependency on animal proteins is not environmentally sustainable, necessitating the identification of alternative smart proteins. Smart proteins are environmentally benign and mimic the properties of animal proteins (dairy, egg and meat) and are derived from plant proteins, microbial fermentation, insects and cell culture meat (CCM) processes. This review critically evaluates the technological, safety, and sustainability challenges involved in production of smart proteins and their consumer acceptance from Indian context. Under current circumstances, plant-based proteins are most favorable; however, limited land availability and impending climate change makes them unsustainable in the long run. CCM is unaffordable with high input costs limiting its commercialization in near future. Microbial-derived proteins could be the most sustainable option for future owing to higher productivity and ability to grow on low-cost substrates. A circular economy approach integrating agri-horti waste valorization and C1 substrate synthesis with microbial biomass production offer economic viability. Considering the use of novel additives and processing techniques, evaluation of safety, allergenicity, and bioavailability of smart protein products is necessary before large-scale adoption.

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.

Protein transition: focus on protein quality in sustainable alternative sources

The current consumption trends, combined with the expected demographic growth in the coming years, call for a protein transition, i.e., the partial substitution of animal protein-rich foods with foods rich in proteins produced in a more sustainable way. Here, we have discussed some of the most common and promising protein sources alternative to animal proteins, namely: legumes, insects, and microorganisms (including microalgae and fungi). The primary objective was to assess their nutritional quality through the collection of digestible indispensable amino acid score (DIAAS) values available in the scientific literature. Protein digestibility corrected amino acid score (PDCAAS) values have been used where DIAAS values were not available. The ecological impact of each protein source, its nutritional quality and the potential applications in traditional foods or novel food concepts like meat analogues are also discussed. The data collected show that DIAAS values for animal proteins are higher than all the other protein sources. Soybean proteins, mycoproteins and proteins of some insects present relatively high DIAAS (or PDCAAS) values and must be considered proteins of good quality. This review also highlights the lack of DIAAS values for many potentially promising protein sources and the variability induced by the way the proteins are processed.

Culinary treatments impact the digestibility and protein quality of edible insects: a case study with Tenebrio molitor and Gryllus assimilis

The escalating global population is anticipated to intensify the demand for high-quality proteins, necessitating the exploration of alternative protein sources. Edible insects are a promising solution, owing to their nutritional richness and sustainability. However, their digestibility and protein quality, particularly after culinary treatment, remains underexplored. In the present study, we investigated the effects of various culinary treatments on the protein digestibility of two insect species, Tenebrio molitor and Gryllus assimilis. Our findings revealed that culinary treatments such as boiling, roasting, drying, and microwave heating significantly influenced the digestibility of both insect species. Notably, drying emerged as the most effective method, leading to a substantial increase in digestibility. Furthermore, we assessed protein quality using the digestible indispensable amino acid score (DIAAS) and found that the choice of the calculation method significantly influenced the evaluation of protein quality. By including the sum of the anhydrous amino acids, we eliminated the potential overestimation of protein content and obtained a more reliable assessment of protein quality. Our results underscore the importance of culinary treatments and calculation methods in determining the suitability of insects as protein sources for human nutrition.

Should we provide edible insects in children's diets?

PURPOSE OF REVIEW

Diets low in animal-source foods or solely consisting of plant-based foods, hardly meet nutrition needs of children, exposing them to inadequate intake of essential nutrients. Thus, including edible insects in children's diets is relevant for meeting nutritional requirements, other potential health benefits, and building more sustainable food systems. Nutrition and health research on insects is novel and still limited. This review covers recently published research between April 2022 and November 2023 focusing on the relevance of including insects in children's diets.

RECENT FINDINGS

Insects provide protein, fat and micronutrients, and are generally nutritionally equivalent to animal-source foods. The protein and fat quality of edible insects varies depending on several factors. Insects also contain chitin which could potentially be beneficial for gut health. For insects to be considered suitable for inclusion in children's diet, they must be accepted. However, children who are unfamiliar with insects respond to them with curiosity and disgust.

SUMMARY

Insect farming can enhance their availability and consumption, potentially addressing nutrition gaps. Furthermore, transitioning from occasional to regular insect consumption requires actual exposure and integration into diets of insects. To affirm the nutrition and health potential of edible insects for children, well designed human studies are essential.

Effect of compositions and physical properties on 3D printability of gels from selected commercial edible insects: Role of protein and chitin

Compositions and rheological properties of alternative protein sources, including honey bee pupa, grasshopper, cricket, earthworm, and scorpion, and their relationships with 3D printing behaviors were investigated. Protein was found to be the major composition in all insects, while chitin exhibited the most variation. At optimal moisture contents, honey bee pupa and earthworm gels displayed sufficient fluidity but resulted in unstable printed structures, as observed visually and microstructurally. Grasshopper and scorpion gels possessed weak fluidity but produced more stable printed structures. Cricket gel exhibited the most balanced flow behavior and self-supportability. Protein-to-chitin mass ratio proved to be a main factor affecting the 3D printing behavior of the gels. Possible mechanisms on how compositions and properties affected the printing behavior of the gels were proposed. Suggestions for improving the 3D printability of insect and invertebrate resembling insect gels were provided based on these proposed mechanisms.

Estimating In Vitro Protein Digestion and Protein Digestibility Corrected Amino Acid Score of Chicken Breasts Affected by White Striping and Wooden Breast Abnormalities

An understanding regarding impacts of growth-related myopathies, i.e., white striping (WS) and wooden breast (WB), on the quality of dietary protein from cooked chicken breast is still limited. This study aimed at comparing protein content and in vitro protein digestion and estimating the in vitro protein digestibility corrected amino acid score (PDCAAS) of cooked chicken meat exhibiting different abnormality levels (i.e., normal, WS, and WS + WB). The results show that the WS + WB samples exhibited lower protein content, greater cooking loss, and greater lipid oxidation than those of normal samples (p < 0.05). No differences in protein carbonyls or the myofibril fragmentation index were found (p ≥ 0.05). Cooked samples were hydrolyzed in vitro using digestive enzyme mixtures that subsequently mimicked the enzymatic reactions in oral, gastric, and intestinal routes. The WS + WB samples exhibited greater values of free NH2 and degree of hydrolysis than the others at all digestion phases (p < 0.05), suggesting a greater proteolytic susceptibility. The in vitro PDCAAS of the WS + WB samples was greater than that of the other samples for pre-school children, school children, and adults (p < 0.05). Overall, the findings suggest that the cooked chicken breast with the WS + WB condition might provide greater protein digestibility and availability than WS and normal chicken breasts.

Dietary Inclusion of Yellow Mealworms (T. molitor) and Lesser Mealworms (A. diaperinus) Modifies Intestinal Microbiota Populations of Diet-Induced Obesity Mice

BACKGROUND

Insect-based proteins are high-quality alternatives to support the shift toward more sustainable and healthy diets. Additionally, insects contain chitin and have unique fatty acid profiles. Studies have shown that mealworms may beneficially affect metabolism, but limited information is known regarding their effects on gut microbiota.

OBJECTIVES

We determined the effects of defatted yellow mealworm (Tenebrio molitor) and whole lesser mealworm (Alphitobius diaperinus) meals on the intestinal microbiota of diet-induced obesity mice.

METHODS

Male C57BL/6J mice were fed a high-fat diet (HFD; 46% kcal) to induce obesity. Obese mice were then randomly assigned to treatments (n = 10/group) and fed for 8 wk: HFD, HFD with casein protein; B50, HFD with 50% protein from whole lesser mealworm; B100, HFD with 100% protein from whole lesser mealworm; Y50, HFD with 50% protein from defatted yellow mealworm; Y100, HFD with 100% protein from defatted yellow mealworm. Lean mice (n = 10) fed a low-fat-diet (10% kcal) were included. Fresh feces were collected at baseline and every 2 wk, with cecal digesta collected at kill. Fecal and cecal DNA was analyzed for microbiota using 16S rRNA MiSeq Illumina sequencing.

RESULTS

In feces and cecal digesta, mice fed mealworms had greater (P < 0.05) bacterial alpha diversity, with changes occurring in a time-dependent manner (P < 0.05). Beta diversity analyses of cecal samples showed a clear separation of treatments, with a time-based separation shown in fecal samples. Widespread microbial differences were observed, with over 45 genera altered (P < 0.05) by diet in cecal digesta. In feces, over 50 genera and 40 genera were altered (P < 0.05) by diet and time, respectively.

CONCLUSION

Mealworm consumption changes the intestinal microbiota of obese mice, increasing alpha diversity measures and shifting bacterial taxa. More investigation is required to determine what mealworm components are responsible and how they may be linked with the metabolic benefits observed in mealworm-fed mice.

Growth Performance, Diet Digestibility, and Chemical Composition of Mealworm (Tenebrio molitor L.) Fed Agricultural By-Products

Humanity's growing demand for animal protein exceeds the capacity of traditional protein sources to support growing livestock production. Insects offer promising partial substitutes, converting low-nutritional quality materials into high-value biomass. Hence, the bioconversion ability of Tenebrio molitor larvae was assessed by using three types of agricultural by-products (broccoli by-product, tigernut pulp, and grape pomace) at different inclusion levels (0%, 25%, 50%, and 100%) in a carbohydrate-based diet. Ten diets were formulated to assess their impact on the growth, diet digestibility, and nutritional composition of the larvae. For each treatment, eight replicates were employed: five for the growth-performance-digestibility trial and three for the complementary test of uric acid determination. The growth was influenced by the type of diet administered. The broccoli by-product resulted in higher larvae weight and a better feed conversion ratio. However, diets based solely on a single by-product (100%) compromised the productivity and diet digestibility. The larvae changed their nutritional composition depending on the rearing substrate, although the amino acid profile remained consistent. In conclusion, the studied by-products have the potential for use in T. molitor rearing as part of the diet but not as the exclusive ingredients, indicating promising opportunities for using agricultural by-products in T. molitor rearing and production.

Yellow Mealworm (Tenebrio molitor) and Lesser Mealworm (Alphitobius diaperinus) Proteins Slowed Weight Gain and Improved Metabolism of Diet-Induced Obesity Mice

BACKGROUND

High-protein diets not only meet amino acid needs but also modulate satiety and energy metabolism. Insect-based proteins are sustainable, high-quality proteins. Mealworms have been studied, but limited information is known about their ability to impact metabolism and obesity.

OBJECTIVE

We determined the effects of defatted yellow mealworm (Tenebrio molitor)- and whole lesser mealworm (Alphitobius diaperinus)-based proteins on the body weight (BW), serum metabolites, and liver and adipose tissue (AT) histology and gene expression of diet-induced obesity mice.

METHODS

Male C57BL/6J mice were fed a high-fat diet (HFD; 46% kcal) to induce obesity and metabolic syndrome. Obese mice were then assigned to treatments (n = 10/group) and fed for 8 wk: HFD: HFD with casein protein; B50: HFD with 50% protein from whole lesser mealworm; B100: HFD with 100% protein from whole lesser mealworm; Y50: HFD with 50% protein from defatted yellow mealworm; Y100: HFD with 100% protein from defatted yellow mealworm. Lean mice (n = 10) fed a low-fat-diet (LFD; 10% kcal) were included. Longitudinal food intake, BW, body composition, and glucose response were measured. At time of killing, serum metabolites, tissue histopathology and gene expression, and hepatic triglycerides were analyzed.

RESULTS

After 8 wk, HFD, B50, and B100 had greater (P < 0.05) weight gain than LFD, whereas Y50 and Y100 did not. Y50, B100, and Y100 had a lower (P < 0.05) BW change rate than HFD. Mealworm-based diets led to increased (P < 0.05) serum high-density lipoprotein (HDL) and reduced (P < 0.05) serum low-density lipoprotein (LDL) concentrations and reduced (P<0.05) LDL/HDL ratio. Mealworm-based diets led to increased (P < 0.05) hepatic expression of genes related to energy balance, immune response, and antioxidants and reduced (P < 0.05) AT expression of genes associated with inflammation and apoptosis. Mealworm-based diets altered (P < 0.05) hepatic and AT expression of glucose and lipid metabolism genes.

CONCLUSIONS

In addition to serving as an alternative protein source, mealworms may confer health benefits to obese patients.

Mealworm larvae (Tenebrio molitor) and crickets (Acheta domesticus) show high total protein in vitro digestibility and can provide good-to-excellent protein quality as determined by in vitro DIAAS

Edible insects, such as mealworms (Tenebrio molitor larvae; TM) and crickets (Acheta domesticus; AD), are a sustainable, protein-dense novel food with a favorable amino acid profile, which might be an alternative to animal proteins. To assess the protein quality of TM and AD, we assessed the digestible indispensable amino acid scores (DIAAS), considering individual amino acids and their ileal amino acid digestibility, using an in vitro model based on the INFOGEST digestion protocol. In addition, we evaluated if various processing and food preparation steps influenced the in vitro digestibility of individual amino acids and the in vitro DIAAS values of TM and AD and compared them to chicken breast as a reference of excellent protein quality. The total protein in vitro digestibility ranged from 91 to 99% for TM and from 79 to 93% for AD and was negatively affected by oven-drying and, to a lesser extent, by chitin-reduction. The in vitro DIAAS values were 113, 89, and 92 for chicken, blanched TM, and blanched AD, respectively, when considering the indispensable amino acid (IAA) requirements of young children between 6 months and 3 years. Across different processing and food preparation methods, the in vitro DIAAS values ranged between 59 and 89 for TM and between 40 and 92 for AD, with the lowest values found in chitin-reduced insects. Due to their similarities to chicken regarding protein composition, total protein in vitro digestibility, and in vitro DIAAS values, TM and AD might be an alternative to traditional animal proteins, provided that suitable processing and food preparation methods are applied. Our in vitro DIAAS results suggest that TM and AD can thus be considered good-quality protein sources for children older than 6 months. The DIAAS calculations are currently based on crude protein (total nitrogen × 6.25), resulting in an overestimation of insect protein content, and leading to an underestimation and potential misclassification of protein quality. The in vitro model applied in this study is a valuable tool for product development to optimize the protein quality of edible insects. Further studies are required to assess the in vivo DIAAS of insects in humans.

Hybrid Sausages Using Pork and Cricket Flour: Texture and Oxidative Storage Stability

This study aimed to study the functionalities of cricket flour (CF) and the effects of the addition of CF on the texture and oxidative stability of hybrid sausages made from lean pork and CF. Functional properties of CF, including protein solubility, water-holding capacity, and gelling capacity, were examined at different pHs, NaCl concentrations, and CF contents in laboratory tests. The protein solubility of CF was significantly affected by pH, being at its lowest at pH 5 (within the range 2–10), and the highest protein solubility toward NaCl concentrations was found at 1.0 M (at pH 6.8). A gel was formed when the CF content was ≥10%. A control sausage was made from lean pork, pork fat, salt, phosphate, and ice water. Three different hybrid sausages were formulated by adding CF at 1%, 2.5%, and 5.0% levels on top of the base (control) recipe. In comparison to control sausage, the textural properties of the CF sausages in terms of hardness, springiness, cohesiveness, chewiness, resilience, and fracturability decreased significantly, which corresponded to the rheological results of the raw sausage batter when heated at a higher temperature range (~45–80 °C). The addition of CF to the base recipe accelerated both lipid and protein oxidation during 14 days of storage, as indicated by the changes in TBARS and carbonyls and the loss of free thiols and tryptophan fluorescence intensity. These results suggest that the addition of CF, even at low levels (≤5%), had negative effects on the texture and oxidative stability of the hybrid sausages.

Nutritional Evaluation of Milk-, Plant-, and Insect-Based Protein Materials by Protein Digestibility Using the INFOGEST Digestion Method

The INFOGEST method is a valuable tool for understanding and monitoring food digestion as an alternative to in vivo assays. However, few studies have compared animal and alternative protein sources in terms of protein quality using the INFOGEST method. This study aimed to evaluate the protein quality of milk-, plant-, and insect-based protein materials by in vitro protein digestibility and in vitro digestible indispensable amino acid score (DIAAS), following the INFOGEST method. Milk-based protein materials had the highest protein digestibility (86.1-90.8%), followed by soy (85.1%) and wheat (82.3%). These materials had significantly higher protein digestibility compared with zein (65.1%), cricket (63.6%), and mealworm (69.5%). Additionally, the mean values of in vitro DIAAS of milk-based protein materials (105.0-137.5) were higher than those of plant- and insect-based protein materials (1.9-91.0). Milk-based protein materials have higher protein quality than plant- and insect-based protein materials by the nutritional evaluation following the INFOGEST digestion method.

Introducing insect- or plant-based dinner meals to families in Denmark: study protocol for a randomized intervention trial

BACKGROUND

Plant- and insect-based foods are promising alternative protein sources. Previous studies have shown that introducing plant-based foods to the diet can reduce meat intake, but no such intervention has explored the effects of insect-based foods.

METHODS

This study aims to integrate alternative proteins to main meals of 80 Danish families through a 6-week two-arm randomized intervention trial to investigate acceptance, consumption, and potential for meat replacement. The primary outcome is the replacement of dietary meat protein with plant- or insect-based protein from the intervention foods assessed through change in daily meat protein intake, proportion of meat protein to total protein intake, and counts of dinner meals with meat and intervention products.

CONCLUSION

The results of this study will contribute to research in alternative proteins and explore the effects of long-term exposure of meat replacement.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05156853 . Registered 24 December 2021.

Proteins from Tenebrio molitor: An interesting functional ingredient and a source of ACE inhibitory peptides

The angiotensin-converting enzyme (ACE) inhibitory potential of the main protein fractions from Tenebrio molitor larvae (TML) was examined to evaluate their use as a novel antihypertensive functional food. Both fractions contained YAN tripeptide, previously reported as responsible for ACE inhibition. Although YAN has been synthesized and was used as a standard for LC-MS/MS quantification and IC₅₀ against ACE was determined, low yields of YAN from TML did not explain adequately the activity of the whole protein fraction. LC-HRMS/MS investigation led to the identification of other three peptides, which were evaluated in silico, synthesized and tested against ACE. Among them, tetrapeptide NIKY showed the most promising activity (52 µM), highlighting once more the potential of TML and paving the way for exploitation in novel foods.

Nutritional Value and Physicochemical Characteristics of Alternative Protein for Meat and Dairy-A Review

In order to alleviate the pressure on environmental resources faced by meat and dairy production and to satisfy the increasing demands of consumers for food safety and health, alternative proteins have drawn considerable attention in the food industry. However, despite the successive reports of alternative protein food, the processing and application foundation of alternative proteins for meat and dairy is still weak. This paper summarizes the nutritional composition and physicochemical characteristics of meat and dairy alternative proteins from four sources: plant proteins, fungal proteins, algal proteins and insect proteins. The difference between these alternative proteins to animal proteins, the effects of their structural features and environmental conditions on their properties, as well as the corresponding mechanism are compared and discussed. Though fungal proteins, algal proteins and insect proteins have shown some advantages over traditional plant proteins, such as the comparable protein content of insect proteins to meat, the better digestibility of fungal proteins and the better foaming properties of algal proteins, there is still a big gap between alternative proteins and meat and dairy proteins. In addition to needing to provide amino acid composition and digestibility similar to animal proteins, alternative proteins also face challenges such as maintaining good solubility and emulsion properties. Their nutritional and physicochemical properties still need thorough investigation, and for commercial application, it is important to develop and optimize industrial technology in alternative protein separation and modification.

In Vitro Protein Digestion of Cooked Spent Commercial Laying Hen and Commercial Broilers Breast Meat

Chicken meat from spent laying hens (SHs) has been considered as nutritive as the meat of commercial broilers (CBs) based on chemical composition. High insoluble collagen in SH meat might reduce protein digestibility and bio-accessibility compared to CB meat. This study aimed at comparing the in vitro protein digestibility of CB and SH cooked breast meat. In the first part, CB samples were digested using two static in vitro digestion methods and collected at different digestion points for determining the degree of hydrolysis (DH). The method providing a greater DH value was chosen for comparing protein digestibility between CB and SH samples. The activities of used enzymes during in vitro digestion were evaluated based on bicinchoninic acid assay 2,4,6-trinitrobenzenesulfonic acid colorimetric method, gas chromatography-mass spectrometry, and sodium dodecyl sulfate-polyacrylamide electrophoresis. Particle size distribution of solid content collected from hydrolysate was also determined. The results showed that after digestion, CB showed 1−3 mg/mL protein concentration lower, while 7−13% DH and 50−96 µmoL/g protein-free NH2 groups higher when compared to those of SH. Based on sodium dodecyl sulfate-polyacrylamide electrophoresis, CB samples exhibited greater intensity of band at MW < 15 kDa than that of SH. Regarding particle size in terms of volume weighted mean (D[4,3]), at the end of the oral phase, the end of the gastric phase, and the beginning of the intestinal phase, D[4,3] of the SH samples were 133.17 ± 2.16, 46.52 ± 2.20, and 112.96 ± 3.63 µm, respectively, which were greater than those of CB (53.28 ± 1.23, 35.59 ± 1.19, and 51.68 ± 1.25 µm). However, at the end of the intestinal phase, D[4,3] of SH and CB, which were 17.19 ± 1.69 and 17.52 ± 2.46 µm, respectively, did not significantly differ from each other. The findings suggested a greater in vitro protein digestibility of cooked CB breast meats than that of SH ones.