Determination of drying kinetics, some physical, and antioxidant properties of papaya seeds undergoing microwave vacuum drying

Abstract

The effects of microwave power (MP, 100–600 W) on the drying kinetics, as well as the physical and antioxidant properties of papaya seeds dried under microwave vacuum drying (MVD) were investigated. The results found that moisture diffusivity increased in the order of 10−8 with an increase in MP. Shrinkage increased from 1.2 to 4.9% and bulk density decreased from 3,441 to 1,091 kg/m3, respectively, while the moisture content decreased. The antioxidant contents of all of the MVD samples were higher than those of the samples dried under ambient air ventilation. An increase in MP decreased the total phenolic content from 14.69 to 10.66 mg gallic acid equivalent per gram dry weight (DW), increased both the β‐carotene and the total flavonoid content in the ranges of 0.2–0.35 mg β‐carotene equivalent per gram DW and 20.71 to 23.51 mg catechin equivalent per gram DW, respectively. Higher values of antioxidant activity were obtained at higher MP. The results have shown that the use of novel MVD technique in appropriate conditions can improve the overall drying efficiency and enhance the total yield of antioxidant content. Practical Applications Papaya seeds have great potential for use as a source of antioxidants. However, the best novel techniques for retaining high values of antioxidant compounds, and therefore recouping value from the wasted seeds, has not been widely reported on. This study has found that combined microwave vacuum drying (MVD) is a very beneficial drying method for the preservation of antioxidant content. A better antioxidant yield from dried papaya seeds was obtained using MVD at a higher MP of 600 W. Trolox equivalent antioxidant capacity of seeds dried using MVD was 27.62% higher than the samples dried using ambient air ventilation.

Fatty acid composition, bioactive phytochemicals, antioxidant properties and oxidative stability of edible fruit seed oil: effect of preharvest and processing factors

“…Microwave drying papaya seeds at 600 W increased the oil extracts Trolox equivalent antioxidant capacity (TEAC) by 17 %, while microwave drying at 100 W decreased TEAC by 8 % ( Bualuang et al., 2018 ). The findings showed that an increase in the microwave power enhanced the oil extracts antioxidant activity.…”

“…Preservation and maximization of these bioactive phytochemicals during seeds drying should be prioritized. Bualuang et al (2018) evaluated the effect of microwave vacuum drying (100 mbar, 100, 300, 450 and 600 W) papaya seeds and found out that total phenolic content significantly improved by 11 %, but decreased by 16 and 20 % when the microwave power was increased from 100 to 300, 450 and 600 W, respectively. In a related study, Al reported a significant effect of oven drying (60, 70 and 80 C for 24 h) kinnow marandin, orlendo orange and eureka lemon seeds on the phenolic compounds of the extracted oil.…”

The effect of various drying strategies on the greenness, chlorophyll, bioactive compounds, antioxidant activity, and anti-tyrosinase of dried Acanthus ilicifolius L. leaves

“…i. MWVD was performed using a microwave oven (Samsung MS23F301E) connected to a vacuum pump (New IM-TECH IM125D) with a pumping rate of 0.108 m 3 /min (Bualuang et al, 2019). Then, 100 g of A. ilicifolius leaves were placed into the vacuum container, and into the oven cavity.…”

“…This thus causes a reduction in the retention of phytochemical compounds in the dried products (Onwude et al, 2016). Furthermore, in comparison to hot air convective drying, both microwave and microwave-vacuum drying can reduce the drying times while maintaining the product quality (Hamrouni-Sellami et al, 2013;Bualuang et al, 2019).…”

Pomegranate Fruit Quality and Seed Drying Method: Effect on the Chemical Composition and Bioactivities of the Extracted Oil

“…Among other factors, the differences observed could be due to variation in cultivar, seed drying method, oil extraction technique, and fruit growing region. Nonetheless, the TPC results were lower than those from other fruit seed oil such as papaya (10.66-13.29 mgGAE/g oil) and avocado (25.72-70.19 mgGAE/g oil) [31,32]. The DPPH assay has been used widely to evaluate the antiradical activity of plant extracts, including seed oil.…”