Nutritional Composition and Protein Quality of Edible Insects

Why Crude Protein Percentage Is Only the Beginning

By TasteLab Scientific Editorial Board

Article: 006
Category: Insect Proteins · Nutrition · Food Science
Scientific Level: Technical / Professional

Keywords: edible insects, insect protein, protein quality, amino acids, protein digestibility, DIAAS, PDCAAS, chitin, Acheta domesticus, Tenebrio molitor, alternative proteins

Abstract

Edible insects are frequently promoted as high-protein foods, but protein concentration alone does not determine nutritional quality.

For food scientists and product developers, four questions are more important:

1. How much true protein does the ingredient actually contain?

2. Does it provide the required indispensable amino acids?

3. How effectively are those amino acids digested and absorbed?

4. How does processing modify the final protein quality?

These questions are especially relevant for insects because conventional protein analysis can overestimate protein content. Chitin and other nitrogen-containing compounds contribute nitrogen without necessarily representing dietary protein. Research has therefore proposed insect-specific nitrogen-to-protein conversion factors rather than automatically applying the conventional factor of 6.25.

At the same time, recent studies show that properly processed mealworm and cricket proteins can demonstrate high in-vitro digestibility and good protein-quality scores. Human research with lesser mealworm protein has also demonstrated efficient amino-acid availability and stimulation of postprandial muscle protein synthesis.

The central conclusion is therefore clear:

Protein quantity is not the same as protein quality.

For the food industry, insect protein should be evaluated as a functional nutritional ingredient using amino-acid composition, digestibility, processing history and analytical methodology—not simply the protein percentage printed on a specification sheet.

Key Takeaways

• Several edible insects contain substantial amounts of protein on a dry-matter basis, but values vary by species, processing and analytical method. House cricket studies have reported approximately 60–70% protein on a dry basis.

• The conventional nitrogen-to-protein factor of 6.25 can overestimate insect protein because chitin and other compounds contribute non-protein nitrogen.

• Protein quality depends on indispensable amino-acid composition and digestibility, not protein percentage alone.

• Mealworm and cricket samples have produced high in-vitro digestibility values, but processing can substantially change the result.

• Limiting amino acids are not necessarily identical across species, ingredients or processing conditions.

• Human clinical evidence exists for lesser mealworm protein, but the human evidence base remains much smaller than that available for established proteins such as dairy.

1. The Problem With Asking Only: “How Much Protein?”

Protein concentration is usually the first number examined on an alternative-protein specification.

That is understandable—but incomplete.

EFSA reported crude protein concentrations of approximately 61.7–68.6 g/100 g for dried and powder forms of an assessed Acheta domesticus novel food. Research conducted by Udomsil and colleagues similarly found approximately 60–70% protein on a dry-weight basis in house and field crickets.

For an EFSA-assessed dried/powder yellow mealworm preparation, the reported average crude protein concentration was approximately 55.6 g/100 g when calculated conventionally from nitrogen.

These numbers immediately demonstrate that insects can represent concentrated protein-containing materials.

But they require an important qualification.

Crude protein is an analytical estimate. It is not necessarily identical to true protein.

2. Why Nitrogen × 6.25 Can Be Misleading

A common analytical method estimates protein by first measuring total nitrogen and then multiplying that nitrogen by a conversion factor.

The conventional factor is:

Protein = Nitrogen × 6.25

This assumes that proteins contain approximately 16% nitrogen.

For many foods, this provides a practical approximation.

Insects create a complication because nitrogen is also present in non-protein compounds, particularly chitin associated with the exoskeleton.

Consequently, measuring total nitrogen can count nitrogen that does not belong to actual protein.

Janssen and colleagues directly investigated this issue in Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens. Their amino-acid-based analysis produced a proposed nitrogen-to-protein conversion factor of 4.76 ± 0.09 for whole larvae, compared with the traditional 6.25. For extracted and purified insect protein, they reported a higher factor of 5.60 ± 0.39.

EFSA has consequently highlighted the same issue in assessments of edible insects, explicitly noting that the conventional 6.25 factor can overestimate true protein content.

TasteLab R&D implication

When evaluating insect ingredients, do not request only:

Protein: XX%

Request:

Protein determination method:
Kjeldahl or Dumas?

Nitrogen conversion factor:
6.25 or species/product-specific?

Amino-acid-based protein:
Available or not?

Two ingredients labelled “60% protein” may therefore not be nutritionally equivalent.

3. Dry Basis vs As-Sold Basis

Another source of confusion is moisture.

A fresh or frozen insect contains substantially more water than a dried powder. Protein therefore appears much more concentrated after drying even if the absolute amount of protein in the insect material has not increased.

For example, EFSA reported house cricket protein around 20 g/100 g in frozen material and above 60 g/100 g in dried/powder preparations.

This does not mean drying created additional protein.

It means water was removed.

Therefore, comparisons between ingredients should specify whether nutritional composition is expressed on:

• wet/as-sold basis, or

• dry-matter basis.

This is fundamental when comparing whole insects, frozen products, powders, concentrates and isolates.

4. Amino-Acid Composition: The Second Question

Humans require nine indispensable amino acids from dietary sources.

A food containing large amounts of protein can still have reduced nutritional value if one indispensable amino acid is present in insufficient quantity relative to human requirements.

House and field cricket samples analyzed by Udomsil and colleagues contained all indispensable amino acids examined in the study.

However, the presence of every indispensable amino acid does not automatically make all insect ingredients nutritionally identical.

The ratio between amino acids matters.

So does digestibility.

And the first limiting amino acid can vary according to insect species, production system, analytical method and processing.

5. Limiting Amino Acids Are Not Fixed

This is an important point for product developers.

Research using commercial cricket and mealworm powders found different limiting amino-acid patterns between the products studied. Stone and colleagues reported lysine as the first limiting amino acid in their mealworm material, whereas tryptophan limited the cricket protein examined.

Hammer and colleagues later found sulfur-containing amino acids to be limiting across their Tenebrio molitor treatments, while tryptophan was the first limiting amino acid in most Acheta domesticus treatments.

These results are not contradictory.

They show why it is dangerous to publish statements such as:

“Cricket protein is always limited by X.”

Protein composition depends on the actual ingredient being used.

TasteLab R&D rule

Use an amino-acid certificate for the commercial ingredient—not a generic amino-acid table downloaded for the species.

6. Protein Digestibility

Amino acids must be released from the food matrix during digestion before they can contribute efficiently to human nutrition.

This is where protein digestibility becomes critical.

Hammer and colleagues studied Tenebrio molitor and Acheta domesticus subjected to different processing methods.

Total in-vitro protein digestibility ranged approximately:

Tenebrio molitor

91–99%

Acheta domesticus

79–93%

depending on processing conditions.

The study found particularly strong performance in minimally processed/blanched samples, while some more intensive processing treatments reduced digestibility.

This produces another key principle:

The protein quality of an insect cannot be separated from the process used to manufacture the ingredient.

7. Chitin and Digestibility

Chitin is a structural polysaccharide associated with insect exoskeletons.

From a nutritional analysis perspective, it creates two separate issues.

First, it contains nitrogen and can therefore contribute to overestimation of crude protein when total nitrogen is converted using 6.25.

Second, the food matrix created by chitin and other structural material can influence digestion.

EFSA considers chitin largely insoluble and not expected to be significantly digested in the human small intestine.

This does not mean that simply removing chitin automatically produces better protein quality.

Interestingly, Hammer and colleagues observed lower digestibility and DIAAS values in some chitin-reduced samples, demonstrating that fractionation itself can modify proteins and food structure.

The relevant R&D question is therefore not:

“Should we remove chitin?”

but rather:

“What does the complete fractionation process do to nutritional and functional performance?”

8. From Amino-Acid Score to PDCAAS

Protein-quality assessment attempts to combine amino-acid adequacy with digestibility.

One established approach is the:

Protein Digestibility-Corrected Amino Acid Score — PDCAAS

PDCAAS evaluates the limiting indispensable amino acid relative to a reference pattern and corrects the result using protein digestibility.

However, insect research illustrates why methodology matters.

A 2024 study by Ochiai and colleagues evaluated five edible insects and found amino-acid scores ranging from 63 to 94, while also demonstrating that chitin affects calculated nitrogen-to-protein conversion and true protein estimation.

A protein-quality number therefore cannot be interpreted properly without knowing:

• the insect species;

• protein analytical method;

• reference amino-acid pattern;

• digestibility method;

• processing history.

9. DIAAS: A More Detailed Approach

A more advanced protein-quality metric is the:

Digestible Indispensable Amino Acid Score — DIAAS

Rather than correcting the whole protein using a single overall digestibility value, DIAAS evaluates the digestibility of individual indispensable amino acids.

This makes it more informative when different amino acids behave differently during digestion.

Hammer and colleagues calculated in-vitro DIAAS for processed mealworm and house cricket samples using the indispensable-amino-acid requirements of children aged 6 months to 3 years.

For blanched samples they obtained approximately:

Protein

In-vitro DIAAS

Chicken breast

113

Blanched Acheta domesticus

92

Blanched Tenebrio molitor

89

Across all processing methods examined, however, the scores varied substantially:

T. molitor: approximately 59–89

A. domesticus: approximately 40–92.

These are in-vitro estimates, not human ileal DIAAS measurements, and the authors specifically noted the need for further in-vivo validation.

That distinction is essential for scientifically responsible communication.

10. Processing Can Improve—or Damage—Protein Quality

ARTICLE 005 examined processing from an industrial perspective.

ARTICLE 006 shows why the same processing decisions matter nutritionally.

Heat can denature protein and potentially increase accessibility to digestive enzymes.

But excessive heating can also:

• promote protein aggregation;

• generate cross-linking;

• encourage Maillard reactions;

• modify heat-sensitive amino acids;

• reduce digestibility.

In Hammer's experiment, oven drying at 90°C negatively affected total protein digestibility in house cricket relative to better-performing treatments.

Therefore:

Blanching ≠ oven drying ≠ freeze drying ≠ protein extraction.

They may begin with the same insect but finish with nutritionally different ingredients.

11. Human Evidence: Can Insect Protein Actually Support Muscle Protein Synthesis?

Laboratory digestibility measurements are useful, but human data are considerably more valuable.

A double-blind randomized study by Hermans and colleagues compared 30 g of lesser mealworm-derived protein with 30 g milk protein concentrate in healthy young men.

During the five-hour postprandial period, approximately 73% of mealworm-derived phenylalanine and 77% of milk-derived phenylalanine appeared in circulation.

Both protein sources increased muscle protein synthesis at rest and after resistance exercise, with no statistically significant difference between the groups for the main protein-synthesis comparisons.

This provides important proof of concept:

At least some appropriately processed insect proteins can behave as nutritionally effective proteins in humans.

But it should not be generalized to every insect species or every insect powder.

The trial studied lesser mealworm protein, a specific dose, a specific processing system and a specific population of healthy young men.

12. Protein Is Only Part of the Nutritional Matrix

Whole insect powders are not protein isolates.

They also contain varying proportions of:

• lipids;

• chitin-containing material;

• minerals;

• carbohydrates;

• micronutrients.

For example, Udomsil and colleagues reported 10–23% lipids on a dry basis in the cricket species they analyzed, alongside their high protein concentration.

This can be nutritionally interesting but introduces formulation consequences.

An insect powder containing 20% lipid behaves very differently from a purified 80–90% protein isolate.

For an R&D department, therefore, the complete proximate composition matters.

13. Protein Concentrate vs Whole Insect Powder

Consider two conceptual ingredients.

Ingredient A

Whole cricket powder

Contains:

• protein;

• lipid;

• chitin;

• minerals;

• flavor-active compounds.

Ingredient B

Cricket protein concentrate

Contains:

• higher relative protein;

• lower levels of some non-protein fractions;

• altered solubility;

• altered sensory profile;

• potentially different digestibility.

Even if both originate from Acheta domesticus, they should not be treated as interchangeable.

The nutritional positioning, protein calculation, ingredient functionality and sensory impact may all differ.

14. What Should an R&D Team Ask a Supplier?

For professional insect-protein development, TasteLab recommends requesting at least:

Composition

• moisture;

• protein;

• fat;

• ash;

• total dietary fibre/chitin where available.

Protein analysis

• Kjeldahl or Dumas;

• nitrogen-to-protein conversion factor;

• amino-acid composition;

• true or amino-acid-based protein where available.

Protein quality

• indispensable amino-acid profile;

• limiting amino acid;

• digestibility data;

• PDCAAS and/or DIAAS methodology if claimed.

Processing

• blanching conditions;

• drying method;

• defatting;

• extraction;

• hydrolysis;

• thermal history.

Safety

• microbiology;

• allergen statement;

• contaminants;

• substrate/feed traceability.

A supplier specification that contains only:

Protein: 65%

is not sufficient for advanced nutritional product development.

15. Application: High-Protein Foods

This becomes particularly important when insect proteins are used in products positioned around a protein claim.

Potential applications include:

• protein bars;

• sports nutrition;

• protein snacks;

• pasta;

• bakery;

• beverages;

• meal replacements;

• frozen desserts.

A formulation should not simply replace:

20 g whey protein

with

20 g insect powder

and assume equivalent nutritional or technological performance.

The developer should consider:

true protein concentration × amino-acid quality × digestibility × serving size × matrix effects.

16. Protein Complementation

An insect protein does not necessarily need to function as the only protein source in a food.

One potentially valuable strategy is protein complementation.

If an insect ingredient is relatively weak in a particular indispensable amino acid, another ingredient with a complementary amino-acid profile can improve the overall protein system.

This opens opportunities for combinations such as:

• insect + dairy;

• insect + legume;

• insect + cereal;

• insect + fungal protein;

• multi-protein functional blends.

The objective should not necessarily be to identify a single “perfect protein”.

It may be more commercially and technically effective to design a balanced protein architecture.

17. The Importance of the Final Food Matrix

A protein ingredient does not exist in isolation once incorporated into food.

The final product may expose it to:

• heating;

• extrusion;

• baking;

• freezing;

• fermentation;

• acidification;

• storage.

Hammer and colleagues demonstrated directly that processing influenced digestibility and in-vitro DIAAS in both mealworm and cricket preparations.

Protein-quality testing performed only on the incoming ingredient may therefore not completely describe the nutritional characteristics of the finished commercial food.

For sophisticated products, final-product validation becomes valuable.

18. TasteLab Protein Evaluation Framework

For insect-based product development, we propose evaluating five dimensions.

01 — Quantity

How much true protein is present?

02 — Amino-Acid Quality

Does the ingredient provide adequate indispensable amino acids?

03 — Digestibility

How effectively can those amino acids become biologically available?

04 — Processing Stability

Does industrial processing preserve or degrade protein quality?

05 — Product Delivery

How much high-quality protein is actually delivered in the consumer serving?

This produces a much more useful assessment than protein percentage alone.

19. A Better Specification for the Future

As the insect-ingredient industry develops, professional buyers should increasingly expect specifications resembling those used for advanced dairy, soy and pea protein ingredients.

Future insect-protein specifications may routinely include:

• true protein;

• nitrogen conversion factor;

• complete amino-acid profile;

• indispensable amino-acid content;

• protein solubility;

• digestibility;

• DIAAS or validated equivalent;

• particle size;

• lipid oxidation parameters;

• functional properties.

This is the transition from “insect flour” to precision food ingredient.

Conclusion

Edible insects can contain substantial concentrations of protein, and research demonstrates promising amino-acid profiles and digestibility for several commercially relevant species. House crickets have been reported at approximately 60–70% protein on a dry basis, while controlled experiments have shown high in-vitro digestibility for both Acheta domesticus and Tenebrio molitor.

But the headline protein percentage can be deceptive.

Chitin and non-protein nitrogen complicate conventional nitrogen-based protein measurement. Amino-acid balance differs between ingredients. Processing changes digestibility. And DIAAS can vary substantially even within the same species depending on processing conditions.

Human research with lesser mealworm protein provides encouraging evidence that insect-derived protein can support amino-acid availability and muscle protein synthesis, but significantly more human data are required before conclusions can be generalized across the category.

For food manufacturers, the correct question is therefore no longer:

“How much protein does this insect contain?”

The better question is:

“How much digestible, nutritionally useful protein will this ingredient deliver in the final food?”

That is the standard by which next-generation insect protein ingredients should be developed.

Frequently Asked Questions

Are edible insects complete proteins?

Studied cricket and mealworm materials can contain all indispensable amino acids, but amino-acid adequacy and digestibility vary by species and ingredient. “Complete protein” should therefore not be treated as a universal quality guarantee.

Is cricket protein equivalent to whey protein?

Not automatically. Protein concentration, amino-acid profile, digestibility and processing differ. Each ingredient requires its own nutritional characterization.

Why can insect protein values be overestimated?

Because chitin and other non-protein compounds contain nitrogen. Multiplying all measured nitrogen by 6.25 can therefore classify some non-protein nitrogen as protein.

Is insect protein digestible?

Yes, several studies report high digestibility, but values depend on species and processing. In one controlled in-vitro study, T. molitor ranged from approximately 91–99% and A. domesticus from 79–93%.

Does processing affect protein quality?

Yes. Hammer and colleagues demonstrated substantial variation in digestibility and in-vitro DIAAS among differently processed cricket and mealworm preparations.

Can insect protein stimulate muscle protein synthesis?

A randomized human trial found that ingestion of 30 g lesser mealworm-derived protein increased postprandial muscle protein synthesis both at rest and following exercise, with responses not significantly different from milk protein concentrate in that study.

Selected Scientific References

1. Udomsil N, Imsoonthornruksa S, Gosalawit C, Ketudat-Cairns M. Nutritional Values and Functional Properties of House Cricket (Acheta domesticus) and Field Cricket (Gryllus bimaculatus). Food Science and Technology Research. 2019;25(4):597–605. DOI: 10.3136/fstr.25.597.

2. Janssen RH, Vincken JP, van den Broek LAM, Fogliano V, Lakemond CMM. Nitrogen-to-Protein Conversion Factors for Three Edible Insects. Journal of Agricultural and Food Chemistry. 2017;65(11):2275–2278. DOI: 10.1021/acs.jafc.7b00471.

3. Stone AK, Tanaka T, Nickerson MT. Protein quality and physicochemical properties of commercial cricket and mealworm powders. Journal of Food Science and Technology. 2019;56:3355–3363. DOI: 10.1007/s13197-019-03818-2.

4. Hammer L, Moretti D, Abbühl-Eng L, et al. 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. Frontiers in Nutrition. 2023;10:1150581. DOI: 10.3389/fnut.2023.1150581.

5. Ochiai M, Suzuki Y, Suzuki R, et al. Low protein digestibility-corrected amino acid score and net nitrogen-to-protein conversion factor value of edible insects. Food Chemistry. 2024;454:139781. DOI: 10.1016/j.foodchem.2024.139781.

6. Hermans WJH, Senden JM, Churchward-Venne TA, et al. Insects are a viable protein source for human consumption: from insect protein digestion to postprandial muscle protein synthesis in vivo in humans. American Journal of Clinical Nutrition. 2021;114:934–944. DOI: 10.1093/ajcn/nqab115.

7. EFSA NDA Panel. Safety of frozen, dried and powder forms of house crickets (Acheta domesticus) as a Novel Food. EFSA Journal.