In tests carried out at the USP, microparticles produced from unripe fruit showed similar performance to the synthetic compound TBHQ, found in processed foods and cosmetics. The results were published in the journal Future foods (photo: researchers collection)
May 13, 2022
Karina Ninni | FAPESP agency – Antioxidants are important substances for the food and cosmetics industries, as they delay the oxidation process of lipid-rich products, such as mayonnaise, margarine, moisturizers and the like. Most of the antioxidants currently used are synthetic and, in Brazil, products that are already banned in other countries, such as TBHQ (tert-butyl-hydroquinone), are still in use.
In the search for natural alternatives, a group of researchers from the University of Sao Paulo (USP) studied the phenolic compounds of acerola and succeeded in extracting antioxidant microparticles as effective as TBHQ from the green fruit. The focus of the research, which is supported by FAPESP, is to develop a process that can be easily adopted on an industrial scale. Recent findings were disclosed in the magazine Future foods.
“There are several studies that show the presence of antioxidant compounds in different sources. But how can we ensure that substances of interest and with great potential for use can be produced on an industrial scale in a technically and economically feasible way? Many studies in the area of biochemistry are carried out on benches or with very small samples, with no conditions to bring to industry. Our goal is to work with processes to obtain products, ingredients in general, with the intention of practical application ”, he summarizes Thais Maria Ferreira de Souza Vieiraprofessor at the Department of Agroindustry, Nutrition and Food at the Luiz de Queiroz Higher Institute of Agriculture (Esalq-USP).
With representative samples (5 to 10 kilos of fruit) and using only water or ethanol as a solvent – petroleum derivatives were avoided due to their toxicity -, the study sought to optimize processes to increase productivity, i.e. to recover from the -pricing as many compounds of interest as possible and, at the same time, reduce energy expenditure and input costs.
“Colleagues in the group were already working with acerola and, in previous studies, compared green and ripe fruit, showing that green acerola has more antioxidant compounds than ripe. What happens is that, on the same tree, there are ripe and unripe fruits, which are harvested together. Unripe fruits end up leaving the pulp unattractive from a visual point of view. So, we understand that using these green fruits to produce a natural antioxidant is a good strategy, ”he says. Bianca Ferraz Teixeirafirst author of the article e Scholarship of scientific initiation at FAPESP.
Process and tests
Samples obtained from a large producer in Junqueirópolis (SP) were washed and freeze-dried (subjected to a process that extracts water from food) for characterization and homogenization. An extract was obtained by adding water to the lyophilized samples, then the material was centrifuged and filtered.
“This extract was atomized in spray dryer [equipamento que promove a secagem do alimento por pulverização e é usada, por exemplo, na produção de leite em pó] and so we got the microparticle. We opted for spray dryer because it is a method already widely used in the sector. It allows you to transform the acerola extract into a powdered antioxidant, which can be stored, marketed and used in a simple way, without undergoing oxidation. In the end it can replace TBHQ, which is also used in powder form, does not spoil easily and mixes well with the product, without altering the color, flavor or aroma, ”explains Teixeira.
To test the effectiveness of the microparticles, the researchers made an emulsion based on oil, emulsifier and water – similar to that found in several products, including mayonnaise, salad dressings and cosmetics – and separated the samples into three groups: the first was additive with TBHQ, the second received the acerola microparticles, and the third (control group) was left without any additives.
“We have added the concentration allowed by current regulations for the synthetic antioxidant and various concentrations of microencapsulated acerola powder. And we saw that the latter was as effective as TBHQ at the same concentration, ”says Teixeira.
Vieira explains that the test in the model system (water in oil) is ideal for exploring the application possibilities of the product and to find out at what concentration the acerola powder is effective. “The natural antioxidants produced on the market already exist. But it is useless to have an encapsulated product of natural origin that requires the application of a large amount to be effective, as cost is often an impediment. Furthermore, the antioxidant cannot change the appearance, color or aroma of the final product. In this work, the aromatic analysis was performed with tasters and there was no sensory difference between the synthetic antioxidant samples and the acerola product.
Teixeira points out that acerola has a high concentration of ascorbic acid (vitamin C) – which is not considered a phenolic compound, but has high antioxidant activity. “The fruit also contains ferulic acid, chlorogenic acid and coumaric acid. But the tests carried out indicate that, in the case of green acerola, what is most present is ascorbic acid ”, he reports.
The researcher reiterates that the effectiveness of acerola is similar to that of synthetic antioxidants. “It was the first product, among all those we tested in the laboratory, to have the same performance. We used TBHQ as a beacon because it is a very efficient substance. But in France, Japan and the United States this synthetic antioxidant is practically no longer used. So finding a natural alternative that is so effective and so easy to apply is a nice result. “
The article Replacement of synthetic antioxidants in food emulsions with green acerola microparticles (Malpighia marginalized) you can access: www.sciencedirect.com/science/article/pii/S2666833522000181.