In tests carried out at USP, microparticles produced from unripe fruit showed similar performance to the synthetic compound TBHQ, present in processed foods and cosmetics. Results were published in the magazine Foods of the Future (photo: researchers’ collection)
May 13, 2022
Karina Ninni | FAPESP Agency – Antioxidants are important substances for the food and cosmetics industry, as they delay the oxidation process of products rich in lipids, such as mayonnaise, margarine, moisturizing creams and the like. Most of the antioxidants currently used are synthetic and, in Brazil, products 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 São Paulo (USP) has been studying the phenolic compounds of acerola and managed to extract, from the green fruit, antioxidant microparticles as effective as TBHQ. 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 results have been disclosed in the magazine Foods of the Future.
“There are several studies that prove 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, without conditions to be taken to the industry. Our goal is to work with processes to obtain products, in general ingredients, with the intention of practical application”, summarizes Thais Maria Ferreira de Souza Vieiraprofessor at the Department of Agroindustry, Nutrition and Food at the Luiz de Queiroz College 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, that is, to recover from the -press as many compounds of interest as possible and, at the same time, reduce energy expenditure and input costs.
“Group colleagues were already working with acerola and, in previous studies, compared green and ripe fruits, demonstrating that the green acerola has more antioxidant compounds than the ripe one. What happens is that, on the same tree, there are ripe and unripe fruits, which are picked together. The unripe fruits end up leaving the pulp not so attractive from a visual point of view. Thus, 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 and scholarship of scientific initiation at FAPESP.
Process and tests
Samples obtained from a large producer in Junqueirópolis (SP) were washed and lyophilized (submitted to a process that extracts water from the food) for characterization and homogenization. An extract was obtained by adding water to the lyophilized samples, and then the material was centrifuged and filtered.
“This extract was atomized in the spray dryer [equipamento que promove a secagem do alimento por pulverização e é usada, por exemplo, na produção de leite em pó] and thus we obtained the microparticle. We opted for spray dryer because it is a method already widely used in the industry. It makes it possible to transform the acerola extract into a powdered antioxidant, which can be stored, marketed and used in a simple way, without undergoing oxidation. Eventually, it can replace TBHQ, which is also used in powder form, it doesn’t spoil easily and mixes well with the product, without causing any change in 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) remained without any additive.
“We 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 product application possibilities and for finding out at what concentration the acerola powder is effective. “Commercially produced natural antioxidants already exist. But there is no point in having an encapsulated product of natural origin that requires the application of a large amount to be effective, as the cost is often an impediment. The antioxidant also cannot change the appearance, color or aroma of the final product. In this work, the aroma analysis was performed with tasters and there was no difference between the samples with synthetic antioxidant and the acerola-based product from a sensory point of view.”
Teixeira recalls that acerola has a high concentration of ascorbic acid (vitamin C) – which is not considered a phenolic compound, but has a 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, of all that we tested in the laboratory, that had 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 quite an accomplishment.”
The article Replacing synthetic antioxidants in food emulsions with acerola green microparticles (marginalized malpighia) can be accessed at: www.sciencedirect.com/science/article/pii/S2666833522000181.