Vacuum Microwave Drying of Acerola Residue: Effects of Pre-treatment and Operating Variables on Main Bioactive Compounds

Abstract

Even though the residue from the processing of acerola (Malpighia emarginata D.C.) has signi cant amounts of vitamin C and other bioactive compounds at the same level as the pulp and the juice of this fruit, it also has a high moisture content level (> 80%). In this work, the drying performance of acerola residue in a microwave oven combined with a vacuum environment was investigated. The effect of pretreatment with ethanol on this drying process was successfully analyzed, together with the in uence of main process variables on the moisture removal and the main bioactive compounds of this by-product of the fruit industry. The values obtained for the bioactive compounds after drying could be classi ed as intermediate concentrations, thus showing a good potential to be used as food additives. The growth of mesophilic bacteria, molds, and yeasts in acerola residues was not observed for the dried material at a nal moisture content below 26.2% (wb). Statement Of NoveltyThe high amounts of vitamin C and bioactive compounds with antioxidant activity in the residues from the processing of acerola justify the growing interest from the fruit processing industry in the development of appropriate techniques for its best use. In this work, a hybrid technology -vacuum microwave -and ethanol pre-treatment, was successfully used in the acerola waste drying. We achieved a shorter drying time and lower product surface temperature, while improved the moisture removal compared to other drying techniques used for this material. This technology is able to maintain the quality of acerola residues, prolonging their shelf life and providing safe moisture and water activity levels.

Microwave-vacuum drying of pulsed vacuum osmotic dehydration-pretreated Yacon as an alternative for preserving fructo-oligosaccharides

“…Microwave drying confers better energy usage, a shorter processing time, and a low exposure time of the food to high temperatures, yielding a product with superior quality (Nogueira et al, 2023;Koné et al, 2013). The combination of microwave drying with other techniques, including vacuum application, allows the incorporation of the advantages of the different techniques, minimizing the disadvantages and achieving better quality.…”

“…Microwave-vacuum (MWV) drying combines heat transfer via microwave and decreased pressure. Therefore, this technology can improve energy efficiency and product quality (Nogueira et al, 2023;Corrêa et al, 2011;Costa et al, 2021). Studies have revealed that MWV drying is suitable for drying temperature-sensitive products, including biopharmaceuticals (Alex et al, 2018) and bioactive compounds (Wojdyło, Figiel, & Oszmiański, 2009) such as FOS.…”

Drying acerola residue in a spouted bed: Fluid dynamic study and functional quality analysis

“…Most acerola production is linked to agribusinesses that produce various products, such as juice, jelly, compote, and especially frozen pulp. The fruit is nutritious, with a high vitamin C content, has strong antioxidant activity, and is a low‐calorie food (da Cruz et al, 2019; Nogueira et al, 2023; Sousa et al, 2011). According to Chang et al (2019), considerable quantities of vitamin C and phenolic compounds in acerola exceed that found in other fruits typically viewed as excellent sources of these compounds, such as grapes, açaí, strawberry, and mango.…”

“…In many cases, these unconventional fractions of fruits and vegetables are even richer in nutrients than their conventional parts (Aiolfi & Basso, 2013; Carvalho Gualberto et al, 2021). In the case of acerola, processing the fruit generates a residue that consists basically of the seeds, bagasse, and peels, from which new products may be derived due to a composition that is rich in ascorbic acid, phenolic compounds, flavonoids, anthocyanins, and organic acids (do Carmo et al, 2018; Nogueira et al, 2023; Reinaldo et al, 2021). Utilizing the residue also helps alleviate an environmental problem, considering the polluting potential of this material (Cunha et al, 2016; Nóbrega et al, 2015).…”

“…Previous studies have explored using dried acerola residue in food formulations, such as pies, cakes, and meat products, and as a source of bioactive compounds for active packaging (Portugal Zegarra et al, 2018;Reinaldo et al, 2021;Rezende et al, 2018). Some studies have examined drying acerola residue using different devices, such as ovens with and without forced air circulation (Barros et al, 2020), tray dryers (Nóbrega et al, 2015;Tedesco et al, 2021), roto-aerated dryers (Silva et al, 2016), microwave ovens ( de Sousa et al, 2020), microwave-assisted rotary drums (Ramadan et al, 2019), infrared-assisted rotary dryers (Silva et al, 2021), radiation-assisted packed bed infrared (Nogueira et al, 2019), microwave vacuum dryers (Nogueira et al, 2023), fixed beds (Duzzioni et al, 2013;Silva et al, 2019), and thick-layer dryers (Silva et al, 2018).…”