A key constituent of the body, protein is essential for life: structural proteins, hormones, enzymes, the immune system—these and more depend on it. The recommended daily intake for a healthy adult is either 0.8 g per kg of body weight as by the European Food Safety Authority, or a dose that delivers 10-15 percent of daily calorie intake according to the World Health Organisation.

In 1960, the average world consumption of protein accounted for approximately 11 percent of the total calorie ration, or approximately 25 g per person per day. Today, consumption has climbed to around 36 g, of which animal protein forms the larger increase—a trend correlating with the increase of gross domestic product.

Vegetable protein consumption has increased by 15 percent, and that of animal protein has doubled, although with enormous variations from one country to another. Such trends are associated with general changes in lifestyles and standards of living.

These raise the problem of the environmental cost of producing protein, as well as the question of how, against a background of regional economic inequality, an ever-growing world population is to be fed while taking into account issues like the sustainability of food consumption patterns, availability, the preservation of natural resources and climate change. As such, fortifying food and beverages with protein becomes more critical and opens up a wide variety of opportunities for manufacturers.

GOOD NUTRITIonAL QUALITY

Despite its importance, the nutritional value of protein has often been neglected. Animal protein tends to be regarded as the benchmark even though excessive consumption may have negative consequences for both the individual and the environment.

The nutritional quality of protein depends on the amino acid profile of the source and on its digestibility. Of the 20 different amino acids that make up proteins, eight are essential because they are not synthesised by the body. We therefore have to depend on our food to obtain their benefits.

The main sources of vegetable protein (Fig. 1) are the leguminous (e.g. pea), cereals, oilseeds, root vegetables, green leaves and fruit; each of these has a specific composition and bioavailability—and therefore varying nutritional values.

Generally speaking, vegetable sources of protein are less concentrated and have a lower caloric value than animal sources, but are richer in complex carbohydrates, fibre, vitamins, minerals and unsaturated fat (oilseeds). At the same time, they are lower in saturated fat and cholesterol, which may bring metabolic and cardiovascular benefits.

Some results tend to show that a diet with more animal than vegetable protein could pose the risk of osteoporosis in elderly women. By contrast, there is a correlation between increased consumption of vegetables and a lower incidence of cancer (plus an increase in life expectancy).

A healthier overall lifestyle—accommodating physical exercise, reduced consumption of alcohol, tobacco, etc.—also plays its part, as does a correlation with a more favourable body composition (less fat).

THE INDUSTRIAL REALITY

The agri-food industry develops vegetal proteins as ingredients, which they obtain from wheat, soybean, pea and lupin. These vegetal raw materials have enhanced bioavailability and concentration. The protein concentration depends on the types of product, i.e. the flours, concentrates or isolates whose nutritional or functional applications may differ.

The concentrates can contain up to 80 percent protein (35-80 percent) wheras the isolates may contain up to 90 percent. Hydrolysates are isolates or concentrates that have been pre-digested by specific enzymes.

The preparation and transformation processes used to obtain these proteins have an impact on the digestibility of the products obtained by modifying, for example, the extent of the indigestible carbohydrate network present in the plant through impacts on network structure, or even by eliminating anti-nutritional factors.

In addition, the concentration or extraction processes seleced may themselves influence the technological or nutritional functionalities of the products. Lastly, special attention today is also focused on the speed—with which the amino acids are used by the body.

For example, casein is typically a slow protein but it is a very important protein. In relation to this characteristic, proteins composed of these amino acids are described as slow or fast.

Likewise, amino acid profiles of different plants are different, incomplete but complementary. For example, when a non-dairy cereal drink is fortified with a legume protein such as pea protein, it would improve the protein content of the drink as well as the bioavailability of amino acids used by the body.

THE YELLOW PEA—GREAT VEGETABLE PROTEIN SOURCE

The yellow pea (Pisum sativum) is a leguminous plant with seeds rich in protein—a composition that varies with variety, environment, culture, genetics, etc. The protein concentration is approximately 25 percent, an amount somewher between cereals (10-15 percent) and soybeans (35 percent).

Growing the pea in a crop rotation system has the advantage of being beneficial for the environment since it requires little water or fossil-based energy and no nitrogen fertiliser, while also helping to cut down greenhouse gas emissions.

In addition, it increases the yield of the crops planted after it and, moreover, requires less acreage to produce a kilogram of protein than many other plants. Beyond that, research has also shown that pea protein can satisfy the nitrogen needs of humans and demonstrates good digestibility and nitrogen retention properties.

During its industrial processing, anti-nutritional factors (lipoxygenases, lectins, tannins and protease inhibitors) are eliminated by clean separation, i.e. without chemical solvents. The concentrate that is obtained therefore contains few anti-nutritional factors and complex sugars, and a low fat content with a favourable fatty acid profile (80 percent unsaturated fatty acids). It also has increased bioavailability.

APPLICATIONS FOR THE DAILY FOOD DIET

The specific but varying composition of various protein preparations obtained from different vegetable sources enables the minimum daily intake recommendations to be achieved, either by consuming a sufficient quantity of proteins that have a complete profile.

For example, almond milk in comparison with cows milk has a low protein content. Therefore, when the almond milk is being enriched or fortified with pea protein, it helps to improve the protein content. This is especially important for consumers and vegans that are looking for a non-dairy and rich plant-based protein diet.

As a supply of ingredients for the food industry, various formats exist and enable manufacturers to meet needs. These can be as varied as those of conventional human food requirements—meat, soups, sauces, pasta, pastries; specific nutrition—bars, powder mixes; specialised nutrition—seniors, vegetarians; and even medicalised nutrition—clinical nutrition.

VEGETABLE PROTEIN AND HEALTH

It is universally recommended that sports enthusiasts and elderly people should increase their daily protein intake. Plant-based protein as well-mixed or completed formulations can favour muscle protein accretion in elderly or muscle repair ad growth in young athletic individuals.

Protein is known to be more satietogenic at isocaloric value than carbohydrates or fats. Little is known about the influence of protein (vegetable/animal) on appetite, calorie intake or weight control, but it would appear that vegetable protein can be as effective as animal ones.

Insulin and the glycaemic control could also be influenced by the nature of the protein. Compared with vegetable protein, the consumption of animal protein has also been positively linked with overweight and obesity.

Many studies have shown that vegetarians tend to be in better health than non-vegetarians. However, we should not forget that these studies are based on model populations in which little or no alcohol is consumed, smoking is avoided and regular physical exercise prevalent. The influence of lifestyle on the benefits observed should not be underestimated.

In line with these trends, the World Cancer Research Fund/American Institute for Cancer Research has drawn up its own recommendations for protecting against cancer: cutting down the proportion of foods with a high caloric density (added sugars, low fibre, rich in fat); increasing and varying the consumption of vegetables, fruit, whole grain cereals and dry vegetables; reducing the consumption of red meat (beef, pork and lamb); and avoiding processed meat products.

Some vegetable proteins are included in the regularly updated list of major allergens (including lupin, soybean, gluten and nuts) and this entails an obligation to label. Conspicuously, yellow pea is not on this list, with no epidemiological evidence for allergy to pea protein available. Similarly, no data has yet been found on pea allergies, although there is data on cross allergies.

CONCLUSION

Plant protein offers health benefits with advantageous nutritional profiles, in particular by mixing its sources. The bioavailability of protein preparations can be improved through the production and extraction processes. Vegetable protein productions sustainability profile is also highly attractive when compared with animal protein, given the formers advantageous economic and ecological cost-benefits, which include preservation of the environment.

Even with these self-evident potential advantages, research work is of course still necessary, on one hand to obtain a better understanding of vegetable proteins nutritional parameters; and on the other to improve our knowledge of human physio-pathological needs. The research will help to identify the complementarities and synergies between the two. Meanwhile, technological improvements can help to make it possible to incorporate protein matter of vegetable origin in most food applications.