Effect of Temperature and Humidity on Oil Quality of Harvested Torreya grandis cv. Merrillii Nuts During the After-Ripening Stage

Abstract

Temperature and relative humidity (RH) influence post-harvest ripening, a crucial stage for quality promotion in some oil plants or fruits. Torreya grandis cv. Merrillii nuts, which are rich in unsaturated fatty acids (UFA), are easily affected by temperature and humidity, and they oxidize quickly during the post-harvest ripening stage, leading to the deterioration of nut quality. In this study, the main nutraceutical components, fatty acid composition, and related metabolic parameters of lipid rancidity under four treatments (20 • C and 70% RH, T20-LH; 30 • C and 70% RH, T30-LH; 20 • C and 90% RH, T20-HH; 30 • C and 90% RH, T30-HH) were measured. The post-harvest ripening process was advanced under HH treatments (T20-HH and T30-HH) compared to LH treatments (T20-LH and T30-LH) and was associated with a shorter time for the seed coat to turn dark black and a faster reduction in starch content. The amount of unsaturated fatty acids significantly increased under the T20-HH treatment, but significantly decreased under the T30-HH treatment from 12 to 16 d of ripening time. The acid value (AV) and lipase activity under the T30-HH treatment remained virtually constant from 12 to 16 d of ripening time, and this was accompanied by a dramatic increase in peroxide value (POV), lipoxygenase (LOX) activity, and relative expression of the LOX2 gene. Meanwhile, a significant positive correlation between LOX activity and POV, malondialdehyde (MDA) content, and O 2 • − content was observed. The results imply that the lower amount of oxidative rancidity induced by the T20-HH treatment is related to the LOX activity induced by down-regulation of the LOX2 gene during the late after-ripening stage. Therefore, the T20-HH treatment not only promoted the postharvest process of T. grandis 'Merrillii' nuts but also delayed lipid oxidation, which was ultimately associated with better oil quality at the late after-ripening stage.

Potential of finite element method to optimize the olive harvester machine (hand‐held rotary harvester)

“…Similarly, the maximum and minimum peroxide values, K232 and K270 were related to the F‐U‐Neoprene and O‐U‐EPR, respectively. It seems the impact enhanced the oxidation of unsaturated fatty acids and activity of the enzyme lipoxygenase, leading to an increase in peroxide (Zhang et al, 2020). In contrast, the amount of chlorophyll, carotenoids, phenol, and flavonoids of samples impacted by EPR was more than Neoprene.…”

Measurement bruise volume of olive during impact test using FEM and quality evaluation of extracted olive oil

“…The maximum and minimum peroxide values were related to extracted oils from Fishemi‐ripped and yellow‐unripe samples, respectively (harvested by Neoprene IH—harvested by Manjid IH). It seems that the impact increased the oxidation of unsaturated fatty acids and increased the activity of the enzyme lipoxygenase (lox), which increased the amount of peroxide (Zhang et al., 2020 ).…”

Transcription factors TgbHLH95 and TgbZIP44 cotarget terpene biosynthesis geneTgGPPSinTorreya grandisnuts

“…NCBI/Primer-BLAST was used out for primer design. The reaction mixture, which had a total volume of 20 µ L, consisted of the following ingredients: 10 µ L of SYBR PCR supermix (Bio-Rad, California, USA), 6 µ L of diethylpyrocarbonate-treated water, 2 µ L of cDNA template diluted 5 times, and 1 µ L of each primer (10 µ M) ( Zhang et al 202 °c ). Data were processed, and relative expression levels were computed using the 2 (−△△Ct) method to look at the differential expression of genes ( Zhang et al 2020b ).…”