Article is available in full to IFST members and subscribers.

Register on the FST Journal website for free

Click the button to register to FST Journal online for free and gain access to the latest news

 

If you are an IFST member, please login through the Members Area of the IFST website. 

 

 

 

 

 

 

 

 

 

 

 

 


New trends in sustainable and healthy food sources: land shrimps and sea crickets

Harmke C. Klunder, Marleen Vrij and Marian Peters consider the potential of edible insects as a future food source

Edible insects as a food source
There are few things more fascinating for food scientists and fanatics than food habits from the past and from other cultures, and how we can learn from these for our future. The traditional habit of eating insects and the potential of edible insects as a future food source are a good example of this.

In China, edible wasp collecting and cooking techniques are documented in a book from the Tang Dynasty (618-907) (1). In Europe, Aristoteles (384-322 BC) wrote about the best taste of a Cicada nymph and in the first half of the 20th century, chafer beetle soup (“Maikäfersuppe”), the taste of which is described as comparable to that of lobster soup, was a highly appreciated dish in Germany and France. These days, approximately 1,900 edible insect species are being consumed worldwide, mainly in Africa, Mexico and Asia, for example, the silk worm and cricket (2). But also in Italy and Greece insects are on the menu in some typical local dishes, such as “casu marzu” from Sardinia, Italy.

These examples show how the use of edible insects as sources for food is widespread, both in non-Western and Western cultures.

Most of us were never confronted with this source as a ‘food product’ when we were young and therefore feel very different about edible crickets than about our daily shrimps, steaks and chicken burgers. Nevertheless, over the past years the interest in insects as a food source has grown tremendously in the Western world. In The Netherlands, for instance, an insect cooking book has been published lately and edible insects for human consumption have been available in shops since January 2008 (3).

This trend is being reinforced by the recent re-evaluation of food patterns and habits, not only by consumers and the food industry but also by governments, due to the increasing trade and globalisation of our food products and the depletion of our raw materials. Global meat consumption is growing and is expected to grow even more in the coming decades because of the increasing wealth in countries such as China. To meet these nutritional needs, larger quantities of protein-rich feed for livestock will have to be produced. Due to the scarcity of these protein ingredients it is necessary to explore new sources. An alternative and sustainable protein source for food and feed can be found in insects and insect meal (4).

Edible insects as a sustainable new food source
Edible insects have been found to be one of the viable and sustainable resources which can play an important role in ensuring the reliable worldwide provision of food in the future.

Firstly, edible insects have been proven to convert feed more efficiently to body mass than conventional livestock. Since insects are cold-blooded not much energy is needed to maintain aconstant body temperature during their growth process. Also, short life-cycles make the rearing of edible insects a process with quick, high yields (2).

Secondly, the Global Warming Potential of edible insects (e.g. mealworms) per kg of edible protein is lower compared to pork, chicken and beef (5). Also, the production of edible insects for human protein
requires much less land.

Edible insects as a healthy new food source

In general, the nutritional value of most consumed edible insect species seems very promising.

Protein values of edible insects are comparable to most meat products (Table 1). In addition, the edible portion of insects is high, since the whole insect can be consumed, while this does not hold for livestock and poultry of which certain parts of the animal (such as bones, skin and intestines) are not directly available for human consumption.

Table 1. Macronutrient composition of various edible insect species compared with various common animal and fish tissues (6, 7).

The nutritional contents of insects can differ between species as well as within species depending on their stage of life (metamorphic stage), their habitat and their diet. For instance, the lipid composition of insects is largely dependent on their diet and metamorphic stage. Insects that were fed products containing high levels of linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), showed an increased level of these fatty acids in their lipids (up to 3% of total lipid) compared to a negligible level when those fatty acids were absent in their diet (8).

Figure 1. Fatty acid profiles of two edible insect lipids compared with various common animal fats and fishmeal (6, 10, 11).
Figure 1. Fatty acid profiles of two edible insect lipids compared with various common animal fats and fishmeal (6, 10, 11). (MUFA: Mono-unsaturated fatty acids.)

Figure 1 shows the fatty acid composition of edible insects and high levels of polyunsaturated acid (PUFA) are obtained compared to lard and tallow. FAO suggested the replacement of saturated fatty acids (SFA) by PUFA to decrease the risk of coronary heart disease (9). Insects have a fatty acid profile which is comparable to fish lipids, with high levels of PUFAs. This means that insects may be regarded as healthy food. Although the health benefits of unsaturated fatty acids are desirable, it should be realised that these acids can also give rise to rapid oxidation.

Vegetable oils have natural antioxidants like tocopherols to protect them from oxidation (11). Fish oils also contain tocopherols but in lower levels (12) than vegetable oils, making marine oils more vulnerable to oxidation. Analyses by Finke (6) of several fish species showed tocopherol levels of 5 to 20 IU/g, which is comparable to fish. If processed and stored properly, the oxidation of the lipids can be kept at a low rate and prevent the formation of rancid components and bad smell.

 

Processing methods
Insects can be processed in several ways, such as the whole ‘recognisable’ insect; or an ‘unrecognisable’ meal or paste, or proteins could be extracted and applied in food products. As the farming of edible insects and
processing them into food products is a new industry, the processing practices should be evaluated thoroughly in order to create a safe and high quality product. Generally, the insects will be processed into a product in a series of steps, that typically include those steps described below.

Harvesting and cleaning. After rearing the insects, harvesting can be done by sieving the insects to remove excess biomass and excreted matter. Further cleaning can be done with water. Insects can be harvested at different life stages, for example as larvae or as adults.

Freezing. The insects are usually frozen at -20°C to slow down and finally stop their metabolism, after which they are ready for further processing. The enzymatic browning reaction (phenolase or phenol oxidase) can occur and turn insect tissue into a brown or black product. To avoid this enzymatic reaction leading to discoloration and the accompanying off-flavour, the time gap between defrosting and heating should be limited. The enzymatic browning reaction can also be prevented by lowering the moisture content, lowering the pH, adding anti-oxidants such as vitamin C, or by heat denaturation of the enzymes (4).

Heating. As for microbiological contamination, a heat treatment will be sufficient to kill Enterobacteriaceae, but the presence of spore-forming bacteria requires specific treatment. A blanching and roasting process step of 10 minutes decreases the total count of microorganisms from approx. 7 log cfu/g to less than 2 log cfu/g in whole insects. The same processing methods reduce the number of bacterial spores by approx. 2 log (13). Bacterial spores, often introduced through soil contact, as in many other food products, should be controlled by appropriate storage conditions (temperature, packaging, etc.) or conservation methods (such as acidification).

Depending on the temperature and duration of the heating step, proteins will change from their native state to a denatured state. Functional properties of proteins will alter during denaturation, which will result in decreased solubility, gelling, emulsifying and foaming properties. The functionality of the remaining protein after a heating process will also depend on the protein level and composition of the specific insect and presence of other components (e.g. additives like salts, acids).

Drying. After the heating step the insects will be dried to prevent spoilage. In general, insects have a moisture level in the range of 55-65%. This is too high to guarantee a long shelf-life. A drying process, which will decrease the moisture content to a level of less than 10%, is necessary to prevent microbial growth. Unprocessed insects have a chitin skeleton which prevents them from dehydration during their lifetime. However, in the drying process this chitin layer also prevents a fast evaporation of moisture, resulting in a longer drying time. The drying time could be decreased if the insects are ground to finer particle, unlike the presented process scheme, optimisation of the process is still in progress.

Besides the need to decrease the moisture level to prevent spoilage during storage, oxidation of lipids can cause problems in products with high levels of unsaturated fatty acids. This phenomenon is well known in the fishmeal producing industry. The separate processing steps influence the stability of the lipids in the final product. The incorporation of air, the destruction of native antioxidants and the presence of oxidation enhancing compounds will all have an effect on the final fat stability.

Product development

Figure 2. ‘Buqadilla’
Figure 2. ‘Buqadilla’

As a new trend in the food industry, product development is as least as important for edible insects as it is in other food products. A very recent example is the development of ‘Buqadilla’ in 2012 (Figure 2). This brand new food product, consisting for 35% processed insects, has been developed in collaboration with supply chain partners from the food industry and specialists. During the development, the aim was to design an attractive and tasty food product. It was important that the insects were not recognised as such in the final product and that the product should be able to be scaled-up on an industrial level.

Various concepts with a variety of ground insects (e.g. different species of buffalo worms and mealworms) were prepared, tested and evaluated. The ‘Buqadilla’ was very well received by test panels and specialists.

Edible insects are an exciting and promising food ingredient which opens up a new world and creates innovative challenges for all food technologists. Let’s get to work!

Harmke C. Klunder was based at the Laboratory of Food Microbiology  Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands. Email: harmke.klunder@gmail.com Web: www.wageningenur.nl
Ir. Marleen Vrij is based at New Generation Nutrition (nGn) in Wageningen. Email: info@ngn.co.nl Web: www.ngn.co.nl
Marian Peters is based at New Generation Nutrition (nGn) in Wageningen. Email: info@ngn.co.nl Web: www.ngn.co.nl

References

1. Chen, X., Feng, Y. and Chen, Z. (2010). Common edible insects and their utilization in China. Entomological Research, 39, 299-303.
2. Van Huis, A. (2013). Potential of insect as food and feed in assuring food security. Ann. Rev Entomology, 58, 563-583.
3. Venik - Verenigde Nederlandse Insecten Kwekers (Dutch Association of Insect Breeders), (Personal communication, 2008).
4. WUR, Livestock Research, Report 638, ‘Insects as a Sustainable Feed Ingredient in Pig and Poultry Diets - a feasibility study’, (October 2012).
5. Oonincx, G. A. B. and De Boer, I. J. M. (2012).Environmental impact of the production of mealworms as a protein source for humans – a life cycle assessment, PLoS ONE, www.plosone.org, December 20, 2012.
6. Finke, M. D. (2002). Complete nutrient composition of commercially raised invertebrates used as food from insectivores, Zoo Biology, 21, 269-285.
7. Hultin, O. H. (1985). Chapter 12. Characteristics of muscle tissue, In: ‘Food Chemistry’, (ed. O.W. Fennema). Marcel Dekker. Food-Chemistry-1997-Fennema
8. St-Hilaire, S. and Cranfill, K. (2007). Fish offal recycling by the Black Soldier fly produces a foodstuff high in omega-3 fatty acids. J. of the World Aquaculture Society, 38, (2).
9. FAO ‘Fats and Fatty Acids in Human Nutrition’, Report of an expert consultation, 10-14 November, 2008, FAO Food and Nutrition Paper. Geneva. FAO, Rome, 2010.
10. Ackman, R. G. (2006). Chapter 13, Marine Lipids and Omega-3 Fatty Acids. In: ‘Handbook of Functional Lipids’, (ed. C. C. Akoh). Taylor & Francis.
11. Stauffer, C. E. (1996). ‘Fats and Oils’. Eagan Handbook Series.
12. Aidos, I. et al. (2001). Upgrading of Maatjes Herring by-products: Production of crude fish oil. J. Agric. Food Chem., 49 (8), 3697-3704.
13. Klunder, H. C., Wolkers-Rooijackers. J., Korpela J. M. and, Nout, M. J. R. (2012). Microbiological aspects of processing and storage of edible insects, Food Control, 26, 628- 631.



View the latest digital issue of FS&T or browse the archive

 

Click here

 
Become a member of the Institute of Food Science and Technology
 

 

Application handbook: Food, Beverages, Agriculture

IFST Twitter Feed