According to many people, the common issue with following a vegetarian or vegan diet is the higher chances of certain nutritional deficiencies despite their many health benefits. This is because some of the plant-based nutrients like iron, calcium, vitamin D, B12 vitamins, and so on have significantly lower bioavailability due to many reasons. But this can be reduced to a certain extent by processing plant-based food, and this is especially important for micronutrients like minerals and vitamins as their deficiency can cause health issues. Read on to know more about food processing techniques to increase the nutritional bioavailability of plant-based foods.
The Importance Of Plant-Based Food Processing
In the last couple of years, more people are switching to plant-based diets like veganism, vegetarianism, and so on. This is because of their many popular health benefits like lowering the chances of developing cardiovascular diseases, preventing obesity, better weight management, reducing the risk of certain types of cancers, and many more. However, those who follow a vegan diet tend to develop certain deficiency diseases because they avoid all types of animal products and by-products. For instance, dairy products are a good source of dietary calcium that is more easily absorbed by the body. Likewise, eggs and poultry are good sources of B12 vitamins that are absent in most plant-based foods.
Dietary nutritional deficiency is also the main reason for malnutrition in resource-poor communities. This is not only due to the insufficient consumption of food but also due to the poor nutritional quality of the food they consume. Compounds like phytates, oxalate, and polyphenols reduce the absorption of micronutrients in plant-based foods. Food processing techniques like soaking, thermal processing, mechanical processing, germination, malting, and fermentation can increase the bioavailability of nutrients, and shared below are the details about them.
When preparing a vegan meal, thermal processing increases the absorption of nutrients like iodine and thiamine. This is because heat destroys antinutrients like thiaminases and goitrogens. Another major compound that reduces the absorption of calcium, iron, and zinc in plant-based food is phytate, and its degradation by thermal processing depends on the Ph, plant species, and temperature applied. It has been found from studies that blanching of leafy greens and boiling of tubers reduces the amount of phytic acid contained in them by 5 to 15%. Besides, applying heat when cooking increases the bioavailability of nutrients like folate, niacin, thiamine, vitamin B6, and carotenoids because they are released from the plant matrix.
However, there is also the risk of certain plant-based nutrients being denatured by the thermal processing of food. For example, carotenoids will be oxidized if excessive heat is applied, and water-soluble nutrients like thiamine, folate, riboflavin, and vitamin C may lose their activity due to water and heat. These issues could be overcome by reducing the cooking time and opting for steaming rather than boiling vegetables.
Grains are an important source of carbohydrates in a vegan diet, and they contain phytate that reduces the bioavailability of minerals like calcium, iron, and zinc. Phytates are found in the outer layers of grains like rice, wheat, and sorghum, and mechanical processing like pounding to remove the bran or germ from cereals reduces the phytate content. Likewise, milling used for making flour has a similar effect of increasing the bioavailability of nutrients found in grains and cereals. But these processes have the slight disadvantage of reducing the content of certain vitamins, and this can be compensated by enriching the milled or pounded flour with lost nutrients.
Like milling and pounding grains, vegetables and fruits can also be mechanically processed to increase their nutrient bioavailability. For instance, the pureeing of tomato increases the dietary absorption of lycopene. It is an excellent antioxidant that benefits cardiovascular health, protects from cancer, and oxidative stress. Likewise, mincing or finely chopping carrots and cooking them releases beta carotenoids from subcellular membranes, and this results in their better dietary absorption. Also, the pureeing of blanched spinach releases the iron contained in them which is easier for the body to absorb.
Soaking or leaching helps to remove or reduce the antinutrients contained in plant-based food like nuts, seeds, whole grains, cereals, and pulses. For instance, it reduces the phytate content, and this depends on factors like the plant species, duration of soaking, pH, and the other conditions under which it is done. For example, simple soaking of unrefined maize can reduce the phytate content in it by up to 50%. This process generally improves the dietary absorption of minerals like iron, zinc, calcium, magnesium, and phosphorus. Apart from this, it reduces the content of other antinutrients like oxalate that reduces calcium absorption.
Fermentation reduces the phytate content of plant-based food; microbial phytase enzyme hydrolyses phytate into lower inositol phosphates. This is because myo-inositol phosphates do not inhibit the absorption of zinc and non-heme iron that is commonly found in plant-based foods. In foods like cassava, soybeans, maize, sorghum, lima beans, cocoyam, and cowpeas, fermentation removes phytates by up to 90%.
These plant-food processing techniques can also be combined to increase nutrient bioavailability when preparing a vegan meal.