Optimization of Microwave and Ultrasound Extraction Methods of Açai Berries in Terms of Highest Content of Phenolic Compounds and Antioxidant Activity

Olaf K Horbańczuk,Ewelina Pogorzelska-Nowicka,Jarosław Wyrwisz,Agnieszka Wierzbicka,Monika Hanula,Małgorzata Moczkowska

doi:10.3390/app10238325

Olaf K Horbańczuk, Ewelina Pogorzelska-Nowicka + Show 4 more

Open Access

https://doi.org/10.3390/app10238325

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Journal: Applied Sciences	Publication Date: Nov 24, 2020
Citations: 19	License type: CC BY 4.0

Affiliation: Warsaw University of Life Sciences

Abstract

Rapid technological progress focuses on lowering costs, labor and time. Thus, in order to minimize the expenses of bioactive compound production, great effort is undertaken to optimize the extraction of these compounds. Green extraction is popular and relatively inexpensive. However, the same extraction method does not always work for all types of matrixes due to the biological diversity of the tissue. Therefore, the purpose of this study was to identify the optimal green extraction method of açai berries (ultrasound or microwaves) able to isolate extracts containing the highest possible number of phenolic compounds with the highest antioxidant activity. The results show that the highest content of total phenolic compounds in the extracts was obtained after the application of a temperature of 45 °C, using ultrasound for 25 min and 45 min, microwaves for 3.16 min and a water bath for 25 min. Ultrasound turned out to be the most effective method of flavonoid extraction. In turn, the highest anthocyanin content was obtained for microwave extraction. Additionally, the application of microwaves for 4.33 min (45 °C) guaranteed the highest ferric-reducing antioxidant activity (FRAP) among the extracts. The results show that the use of microwaves shortens the açai extraction time and ensures both a high content of total phenolic compounds and strong antioxidant activity in the extract.

Highlights

In recent years, the nutritional awareness of consumers has increased significantly [1,2]
The extracts obtained with the microwave method were characterized by the lowest content of total phenolic content (TPC) compared to other types of extraction
Comparing TPC at the same temperature (25 ◦ C), regardless of the type of extraction used, the content of these compounds was at a similar level

Summary

Introduction

The nutritional awareness of consumers has increased significantly [1,2]. Grocery customers are more frequently looking for healthy food rich in bioactive compounds. Phenolic compounds are a well-known and large group of bioactive substances, which are commonly spread in nature. Phenolic compounds regulate the number of free radicals formed during metabolomic transition, inhibit the growth of microorganisms, and extend the freshness and acceptance of products [3,4,5]. Manufacturers are looking for new natural sources to be used in functional foods [1,2]. (açai) is a plant assigned to the family arecaceae, originating from Amazonia and characterized by a high number of phenolic compounds. Açai is considered a “superfruit” because it contains many secondary metabolite compounds (it was identified as having about 90 bioactive compounds: 31% are flavonoids, 23% phenolic compounds, 9% anthocyanins, 11% lignoids) [1,6]

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