Opinion

Volume 12, December 2020, pages 1-2

Food processing and effects on bioactive constituents: an opinion piece

Processing is a unit operation that is often carried out to convert certain raw material intended for use as food. However, pre-processing may often be used to clean, tamper, or to remove husk and shells from raw materials. Conversion of the raw material into food often requires processing that may be thermal or non-thermal. The impact of processing on the products depends further on the degree of processing which may be categorised as minimally processed, regularly processed and ultra processed. Although several systems have been proposed, the NOVA system has received considerable attention and has generated much discussion and controversies. In this system, food is categorized in four groups as unprocessed, processed culinary ingredients, processed, and ultra-processed (UPF). Ultra-processed foods are defined as mass production formulations that contain a high amount of salt, sugar, and oil/fat and may provide insufficient amounts of fibre, micronutrients and bioactive compounds. Such foods are generally energy-dense and designed to be highly palatable and convenient (Monteiro et al., 2018). This system was first proposed by Monteiro and colleagues (2010) who associated such foods with increasing risk of a multitude of non-communicable diseases. This system has been increasingly accepted by some government regulators although has been opposed by some major companies and interest groups. Although one may infer that UPFs are certain types of ready-to-eat products that are rich in salt, sugar, and fat along with a long list of chemical ingredients and preservatives, one should pay attention to the fact that there are many variations in such foods and while presence of too much salt, sugar and fat, especially trans fat, is not healthful, use of certain additives and preservatives is essential for safety and wholesomeness of food and the elimination of pathogenic microorganisms. Additionally, the modern food chain relies on the transportation of raw materials and finished products across large distances. Therefore, preservatives help prevent contamination and spoilage before foods reach the consumers’ table (Carocho et al., 2014). However, uncontrolled use of additives may not necessarily help consumers as they may pose problems of their own as it is the dose that makes the poison. Therefore, search for natural alternatives, when and where possible, must continue. Nonetheless, safety aspects and potential toxicity of natural products must also be carefully examined as natural cannot always be equated with healthful. For example, formation of acrylamide in preparation of French fries may be noted (Mesias et al., 2019). Meanwhile, high level of oxidation products in polyunsaturated oils, if not processed properly, is responsible for off-odors and formation of toxic compounds (Shahidi and Zhong, 2010). However, presence of a minute amount of oxidation products is responsible for the appealing aroma of donuts and French Fries. Therefore, a balance among different factors involved should govern the choice of processing and its level/intensity in the formulation and preparation of food, either industrially or domestically.

In this regard, half-baked solutions should also be avoided. For example, using modified celery juice as an alternative to direct use of nitrites may lead to products that have more residual nitrite than those prepared directly with nitrites (Sebranek and Bacus, 2007). This sort of manipulation may even be considered unethical by some and both scientists and manufacturers should pay attention to details so that the consumer is not fooled by misuse of terminologies. In addition, food that is subjected to new processing methods using sophisticated technologies, such as high-pressure processing (Huang et al., 2017), should not be included in this category. Minimally processed and whole foods are always preferred if safety aspects are carefully considered as this would have an impact on the retention of healthful bioactive compounds (Ramos et al., 2018). Thus, phenolic compounds may be affected by processing, either due to oxidation or reaction/interaction with other food components, hence may have their efficacy compromised (Randhir et al., 2008). However, heat processing in preparation of tomato paste makes lycopene more bioavailable due to a trans to cis isomerization in the molecule (Unlu et al., 2007).

In consideration of ultra processed foods, junk food should not necessarily be equated with this type of processing. However, there is much confusion and controversy over the categorization of junk food and definitions obscured by sensational arguments are not helpful. Nonetheless, condemnation of UPF consumption due to its potential association with a number of diseases, especially its relationship with the prevalence of obesity in high-income countries (Lin et al., 2018), has resulted in revisiting of the formulations by multi-national companies and delivery of somewhat better food and beverages to the public. The responsible action of the progressive segment of the food industry has therefore been essential for striving to develop new products that ensure wholesomeness and nutritional value of a safe and sustainable food supply to address the needs of consumers. In this regard, we now witness beverages with reduced sugar content, prepared food with a lower content of salt and inclusion of certain minerals, such as calcium, vitamins (e.g., vitamin C and D), and bioactives such as phytosterols as well as other ingredients and fiber in a variety of forms and in different product formulations, including baked goods (Ambigaipalan and Shahidi, 2015; Ferguson et al., 2019). Air frying instead of deep fat frying and other precautions have also contributed to a healthier food supply but one should always remember that sensory quality of food as reflected in a desirable taste, appealing flavor and texture is essential for providing products that makes eating pleasurable and not just as a source of nutrients.