Bettina Hänny

The following blog takes an approach to illustrate the potential of insects and microalgae turning organic residues into biomass in order to pose an alternative food source for the growing global food demand.

The amount of organic waste

A whole number of organic residues occur globally in the form of food waste, green biomass, wood, feces, straw, manure etc. Approximately one third of food produced for human consumption is globally lost or wasted. This amounts to about 1.3 billion tons per year. This unpreventably means that large amounts of resources used in producing food are used to no purpose, and that greenhouse gas emissions caused by production of food that gets either lost or wasted are also emissions in vain.
In the sequel numbers particularly focused on food waste will be discussed, since this problem has arisen in the last decades and could with little cost be a major resource for insects and microalgae to be converted into something of use.
On the whole, per-capita  significantly more food is wasted in the industrialized western world than in developing countries.
In the industrialized world food is to a significant extent wasted at the consumption stage, meaning that it is disposed of even if it is still edible.
Interestingly enough, in developing countries food is lost mainly during the early stages of the food supply chain, much less food is wasted at the consumer’s level. It is estimated by the FAO that food waste on the consumer end in Europe and North-America is 95-115 kg/year per capita.

Another important aspect is, due to quality standards food can be wasted by reason that irregular shape or form appears.
The comestible good which seems to be thrown away significantly often in the regions of Europe including Russia, North America and Oceania and industrialized Asia is cereals. All regions throw away between 20% and 27% of the cereals purchased. In North America and Oceania numbers suggest that roots and tubers are thrown away at a level of 30 %, whereas seafood and fish seem to be discarded of at a percentage of  33%.

New utilization strategies apart from the already existing composting, anaerobic digestion and incineration are needed to fully profit from general organic residues’ potential in order to create value added compounds.

Insects and microalgaes’ potential to process organic residues

Cultivating microalgae and insects using organic waste as a nutritional source has been variously tested (more intensively on insects than on microalgae) and is being further studied and  improved. The potential lies in the fields of productivity to increase yield, biomass production and different ways of using the produced biomass.
It has been proven that heterotrophic insects and algae both convert a notable part of organic residues into biomass, thus reducing the hardly usable organic waste and turning it into something more easily accessible and useful. The range of organic compounds is alike in both organisms, thus making utilization for food and feed aligned.
Along with cultivation processes a range of advantages and disadvantages of the corresponding utilization processes arise. Following, some aspects are discussed.

One advantage for breeding microalgae is that genetic changes can be implemented rather quickly with up-to-date technologies.
The advantage of biomass production via insects lies in the dropping necessity to sterilize or hydrolyze the organic residues. This offers a very easily feasible production process applying very simple equipment.
The disadvantage on the other hand of biomass production via microalgae lies in the requirement of a pretreatment to sterilize and (in a large number of trials) hydrolyze.
Further, microalgae biomass production can be carried out in water, which opposes to the vanishing available land for production.
Intriguingly, the volumetric productivity in insects’ biomass outnumber the microalgaes’ productivity, yet both heterotrophic insects and microalgae have been shown to succesfully convert a majority of the fed organic waste into usable compounds.
One aspect that needs to be highlighted is that legal restrictions for genetically modified organisms (GMOs) currently hinder broad application of certain types of microalgae and insects to be converting organic waste into edible biomass.

Insects and microalgae as an alternative food source

Have you ever heard of the word ‘entomophagy’? It describes the consumption of insects. The fact that this word exists shows already the importance of insects an alternative food source also in the regions where it has not yet been part of the daily eating habits. The world needs alternative food sources since the demand for food is growing. The FAO suggests that by 2050 the global food demand will double in respect to 2009, since a population of 9 billion people is expected by 2050 and along with that more people are expected to come out of poverty, thus creating an exponential rise in demand.
Simultaneously, the land being available for production is limited. This is one of the reasons why more land and resource-efficient food production is compulsory in order to disclose the capacity to feed the future population.
Estimations show that insects are found in at least 2 billion peoples’  traditional diets. Reportedly, around a number of 1’900 insect species have been used for food.
Globally, the most commonly consumed insects are beetles (Coleoptera) (31 percent), caterpillars (Lepidoptera) (18 percent) and bees, wasps and ants (Hymenoptera) (14 percent).Following these are grasshoppers, locusts and crickets (Orthoptera) (13 percent), cicadas, leafhoppers, planthoppers, scale insects and true bugs (Hemiptera) (10 percent), termites (Isoptera) (3 percent), dragonflies (Odonata) (3 percent), flies (Diptera) (2 percent) and other orders (5 percent).

Notably high is the feed conversion efficiency of insects. Crickets, as an example, need 2 kilograms only for every 1 kilogram of bodyweight gain. Cattle, on the contrary, need 10 times their body weight.
To highlight again, insects can be grown on organic side-streams including human and animal waste and can thus help minimize environmental contamination. Insects account for emitting less ammonia and fewer greenhouse gases than pigs or cattle and require drastically less land and water than rearing cattle.

Insects as a food source are very nutritious with high protein, fat, fibre, vitamin and mineral content. The nutritional value of along the insects differs because of the broad range of the edible insect breeds. Additionally, the nutritional value differs depending on the metamorphic stage of the insect, the habitat in which it lives, and its diet. To illustrate insects’ dietary potential let us have a look at mealworms. Its proportion of fatty acids unsaturated omega-3 is similar to that in fish (and higher than in pigs and cattle), and the protein and vitamin content of mealworms is comparable to that in fish and meat.
Extracting proteins, fats, chitin, minerals and vitamins is possible. Presently, such extraction processes are too expensive and will require to be further developed to render them profitable and applicable for industrial use in the food sectors.
In general, international trade in insects for food is insignificant. The yet existing trade to developed countries is often driven by demand from immigrant communities or because of the development of niche markets.
Despite all, in most industrialized countries, entomophagy  is regarded as something disgusting and  eating insects is associated with primitive behavior. This is a noteworthy reason why insects in agricultural research have been neglected.
This misconception is being held nonetheless insects deliver fundamental ecological services to our all survival. Just to name a few examples: insects play an important role as pollinators, they improve soil fertility through waste bioconversion, insects provide a spectrum of valuable products such as honet, silk and medical products such as maggot therapy in the cheese industry.

One of the very important factors in malnutrition is the protein share of diets.
By establishing specifically microalgae in the food sector, the opportunity arises to address the supply of protein-rich products globally in an environmentally sustainable and efficient way. Many types of algae are from a nutritious perspective complete food, the algaes’ yields outperform a high number of plant crops, and the development in improved strains of algae is growing.

Conclusion

Food production must clearly increase vastly to attain the future demands of a larger and more affluent global population.
Even though nowadays legal restrictions hinder the usable biomass from being produced, statistics suggest insects and microalgae will in future be applied broadly as an alternative food source. Research on insects for food purpose has been put into practice more broadly than on microalgae, yet further studies are required on both organisms to demonstrate their full potential.
Providing validated information on the potential of microalgae and insects as food is necessary to drive insects and microalgae on investment, political and research agendas worldwide. Clear legal framework at (inter)national could support the development in production and trade in microalgae and insect products as a food source.

Sources 

Pleissner D. & Rumpold B., 2018, Utilization of organic residues using heterotrophic microalgae and insects, waste management.
Torres-Tiji, Y. et al., 2020, Microalgae as a future food source, Biotechnology advances.

Van-Huis, A. et al., 2013, Edible insects: Future prospects for food and feed security, FAO forestry paper.

FAO, 2011, Global food losses and food waste – Extent, causes and prevention, Rome.