Ohmic Heating Extraction at Different Times, Temperatures, Voltages, and Frequencies: A New Energy-Saving Technique for Pineapple Core Valorization

Abstract

Pineapple core is considered a processing by-product. This study proposed and evaluated an ohmic heating extraction-based valorization platform to obtain value-added bioactive compounds from pineapple core and studied the effects of four important processing parameters. In this sense, a Taguchi design (L16(4)4) was used to assess the effects of temperature (70, 80, 90, and 100 °C), time (15, 30, 45, and 60 min), voltage (110, 160, 210, and 260 V), and frequency (60, 340, 620, and 900 Hz) on heating rate, come-up time, energy consumption, system performance efficiency, total phenolic compounds (TPC), DPPH, and ABTS. Finally, a side-by-side comparison of optimized ohmic heating (OOH) and conventional extraction was performed, and chemical composition was compared by ultra-performance liquid chromatography equipped with photodiode array detection-mass (UPLC-DAD-ESI-MS-MS). According to the results, increasing temperatures enhanced system performance efficiency but negatively affected TPC and antioxidant values above 90 ℃. Similarly, prolonging the extraction (>30 min) decreased TPC. Further, increasing voltage (from 110 to 260 V) shortened the come-up time (from 35.75 to 5.16 min) and increased the heating rate (from 2.71 to 18.80 °C/min−1). The optimal conditions were 30 min of extraction at 80 °C, 160 V, and 900 Hz. Verification of the optimal conditions revealed that OOH yielded an extract with valuable bioactive compounds and saved 50% of the time and 80% of energy compared to the conventional treatment. The UPLC-DAD-ESI-MS-MS showed that there were similarities between the chemical profiles of the extracts obtained by conventional and OOH methods, while the concentration of major compounds varied depending on the extraction method. This information can help achieve sustainable development goals (SDGs) by maximizing the yield and minimizing energy and time consumption.

Comparison of ohmic heating‐ and microwave‐assisted extraction techniques for avocado leaves valorization: Optimization and impact on the phenolic compounds and bioactivities

“…Both higher values for voltage gradient and extraction time increased the TPC at a certain point and then decreased. A recent study analyzed the effect of higher voltage and longer heating time on the phenolics from pineapple cores using ohmic heating (Gavahian & Chu, 2022 ). It was obtained that increasing the voltage up to 30 V resulted in a significant increase in phenolic extraction efficiency but increasing the voltage beyond 30 V did not result in further improvement in the extraction efficiency.…”

“…The phenolic composition and amounts in avocado leaves can vary depending on different factors such as solvent and extraction type, maturity and cultivar of leaves, temperature, and extraction time (Castro‐López et al, 2019 ; Che‐Galicia et al, 2020 ). On the other hand, the fast, efficient, and significant amount of phenolic extraction from avocado leaves by OHAE could be explained by not requiring high temperatures or strong solvents and providing the destruction of the cellular matrix through electrical application to enhance the greater release of phenolic compounds (Gavahian & Chu, 2022 ).…”

“…The OHAE extract was analyzed for its phenolic compound composition, and the results indicated that the most abundant phenolic compound was epicatechin, followed by chlorogenic acid, rutin, protocatechuic acid, p-hydroxybenzoic acid, and cinnamic acid, in decreasing order of concentration. On the other hand, the major phenolic of the MAE extract was detected as chlorogenic acid followed by epicatechin, matrix through electrical application to enhance the greater release of phenolic compounds (Gavahian & Chu, 2022).…”

An overview of ohmic heating utilization in the processing of food

“…However, these compounds are generally less stable and can be damaged by high temperatures in conventional extraction processes. Ohmic technology, which uses electric voltage, is considered more effective in maintaining active compounds' effectiveness and more capable of saving energy and processing time [47]. Other studies have demonstrated that low-energy electric fields and thermal processes can be combined and optimized to extract anthocyanins and phenolic compounds from plant tissues in a single phase.…”

Valorized pineapple waste by conventional and energy-saving ohmic extraction: potentially toxic elements and mycotoxin contamination

“…The pineapple processing industry generates a considerable volume of waste considering pineapple annual production statistics (about 40 Mt) and discards of its unpalatable parts (e.g., core, crown, and peel), which is about 60% of the total weight (Gavahian and Chu, 2022b;Hussain et al, 2022;OECD/FAO, 2021). Dealing with such vast agricultural waste has been an environmental challenge (Hikal et al, 2021;Samota et al, 2023).…”