Protein, from source to digestibility: important for healthy ageing

Global demographic shifts and a world population projected to reach 9.7 billion by 2050 lead to an increasing demand for high-quality nutritional products, especially for elderly people. This will put pressure on food production and protein supply. To meet this growing demand, producers are combining vegetable and animal proteins and finding innovative ways to use available proteins more efficiently. The biggest challenge is developing high-protein applications with the right properties (structure, texture, flavour, digestibility) without increasing the food product’s carbon footprint.

Everyone needs protein

Elderly people need to maintain their muscle mass, so their diet must contain enough highly digestible protein. Other consumers need foods that help control weight and reduce the risk of obesity. For them, too, high-protein products can play an important role because they create a relatively high sense of satiety.

While proteins have obvious benefits, products with a high protein content can be undesirable from a sensory perspective: too viscous and hard to swallow in liquids, or too chewy in a solid state. Texture problems can also occur in low-fat products where fat has been replaced with extra protein. These products are perceived as drier and less juicy. To improve consumer acceptance of high-protein products, it is crucial to control their viscosity and texture. This means decreasing liquid products’ viscosity and improving the overall mouthfeel of both liquid and solid products.

Optimal digestibility

To meet the growing demand for protein, food manufacturers are turning to high-quality proteins from alternative sources, such as plants, algae and insects. The industry is also increasingly interested in pea protein, which has a good amino acid composition. However, digestibility is also of importance. Using Nizo’s SIMPHYD platform for in vitro modeling of food’s behaviour in the stomach, the digestibility of pea protein was compared with that of whey and casein proteins. Whey protein hardly increases in viscosity in the stomach, is easily degraded and hence readily available for absorption, making it ideal for rapid muscle recovery (as a ‘fast’ dietary protein). Casein, on the other hand, becomes significantly more viscous and is broken down slowly and absorbed later, making it more suitable for long-term recovery (a ‘slow’ dietary protein). Compared to whey and casein, pea protein turned out to be exactly in the middle. It creates some viscosity and breaks down more quickly than casein, but slower than whey. In other words, it is a moderately fast protein. This knowledge is essential for developing products than promote rapid recovery after a workout or products that can help maintain long-term muscle function.

In vivo measurement

Laboratory animals are sometimes used to test digestibility in an in vivo situation. As digestion takes place in the small intestine, this is also the spot where we would prefer to measure digestibility of proteins in humans.

The small intestine is essential for our health as this is where about 90% of nutrients are absorbed and key signals are generated to control our metabolism and immune system. There is increasing scientific evidence that an imbalance in our intestinal microbiome can lead to a number of diseases, including metabolic and immunological disorders such as obesity, diabetes, and inflammatory diseases. However, most studies focus on the fecal microbiome in the large intestine and pay scant attention to the possible role of the small intestinal microbiome. However, taking samples from the small intestine is a highly invasive procedure, requiring insertion of a tube through the esophagus and stomach.

At Nizo we recently made significant progress in solving this problem by developing the IntelliCap, a minimally invasive technology for taking samples from the small intestine. This measurement device, which had already been CE-marked for drug delivery and real-time measurement of temperature and pH in the gastrointestinal tract, was also approved for the aspiration of fluids. Therefore, the IntelliCap CR system can now also sample the small intestinal microbiota. Philips spin-off Medimetrics Personalized Drug Delivery BV developed the sampling device, which measures only 11mm by 26mm. This capsule has proven its worth as a means of measuring the microbiome in the small intestine, and could possibly also measure in vivo digestion of protein in the small intestine. This enables a more accurately assessment of digestibility, and hence the quality of different types of protein.

Processing

Just as the source of protein affects its digestibility, the way of processing could also have an impact on digestibility and hence the quality of proteins. Go4Dairy, a recently launched research programme, focuses on the impact of glycation on protein’s nutritional value. In the literature, Maillard products are associated with negative health effects, including hypersensitivity of the immune system, reduced digestibility, reduced bioavailability of lysine in particular, changes in gut bacteria and even carcinogenic effects. Much remains unknown, however. Go4Dairy’s aim is to reduce and control the glycation of proteins so as to optimise their nutritional value.

Proteins for the future

High-quality proteins are essential in our diet and are crucial for healthy ageing. In view of the impending protein shortage, current technological developments in plant protein structure, texture, taste and digestibility are all important steps toward creating a sustainable protein supply for a growing world population.

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