Exogenous melatonin prolongs raspberry postharvest life quality by increasing some antioxidant and enzyme activity and phytochemical contents.

There is a growing trend towards enhancing the post-harvest shelf life and maintaining the nutritional quality of horticultural products using eco-friendly methods. Raspberries are valued for their diverse array of phenolic compounds, which are key contributors to their health-promoting properties. However, raspberries are prone to a relatively short post-harvest lifespan. The present study aimed to investigate the effect of exogenous melatonin (MEL; 0, 0.001, 0.01, and 0.1 mM) on decay control and shelf-life extension. The results demonstrated that MEL treatment significantly reduced the fruit decay rate (P ≤ 0.01). Based on the findings, MEL treatment significantly increased titratable acidity (TA), total phenolics content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC). Furthermore, the MEL-treated samples showed increased levels of rutin and quercetin content, as well as antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reduction activity potential (FRAP). Additionally, the samples exhibited higher levels of phenylalanine ammonia-lyase (PAL) and catalase (CAT) enzymes compared to the control samples. Moreover, the levels of pH, total soluble solids (TSS), and IC50 were decreased in the MEL-treated samples (P ≤ 0.01). The highest amount of TA (0.619 g/100 ml juice), rutin (16.722 µg/ml juice) and quercetin (1.467 µg/ml juice), and PAL activity (225.696 nm/g FW/min) was observed at 0.001 mM treatment, while, the highest amount of TAC (227.235 mg Cy-g/100 ml juice) at a concentration of 0.01 mM and CAT (0.696 u/g FW) and TAL activities (9.553 nm/100 g FW) at a concentration of 0.1 mM were obtained. Considering the lack of significant differences in the effects of melatonin concentrations and the low dose of 0.001 mM, this concentration is recommended for further research. The hierarchical cluster analysis (HCA) and principal component analysis (PCA) divided the treatments into three groups based on their characteristics. Based on the Pearson correlation between TPC, TFC, TAC, and TAA, a positive correlation was observed with antioxidant (DPPH and FRAP) and enzyme (PAL and CAT) activities. The results of this study have identified melatonin as an eco-friendly compound that enhances the shelf life of raspberry fruits by improving phenolic compounds, as well as antioxidant and enzyme activities.

24-Epibrasinolide Modulates the Vase Life of Lisianthus Cut Flowers by Modulating ACC Oxidase Enzyme Activity and Physiological Responses.

Ethylene is the most important factor playing roles in senescence and deterioration of harvested crops including cut flowers. Brassinosteroids (BRs), as natural phytohormones, have been reported to differently modulate ethylene production and related senescence processes in different crops. This study was carried out to determine the effects of different levels of 24-epibrassinolide (EBL) on ACC oxidase enzyme activity, the final enzyme in ethylene biosynthesis pathway, vase life, and senescence rate in lisianthus cut flowers. Harvested flowers were treated with EBL (at 0, 3, 6, and 9 µmol/L) and kept at 25 °C for 15 days. The ACC oxidase activity, water absorption, malondialdehyde (MDA) production and vase solution absorption rates, chlorophyll and anthocyanin contents, and the vase life of the flowers were evaluated during and at the end of storage. EBL at 3 µmol/L significantly (p ≤ 0.01) enhanced the flower vase life by decreasing the ACC oxidase activity, MDA production and senescence rates, and enhancing chlorophyll and anthocyanin biosynthesis and accumulation, relative water content, and vase solution absorption rates. By increasing the concentration, EBL negatively affected the flower vase life and postharvest quality probably via enhancing the ACC oxidase enzyme activity and subsequent ethylene production. EBL at 6 and 9 µmol/L and in a concentration dependent manner, enhanced the ACC oxidase activity and MDA production rate and decreased chlorophyll and anthocyanin accumulation and water absorption rate. The results indicate that the effects of brassinosteroids on ethylene production and physiology of lisianthus cut flowers is highly dose dependent.

Effect of Aloysia citrodora Essential Oil on Biochemicals, Antioxidant Characteristics, and Shelf Life of Strawberry Fruit during Storage.

Strawberry fruits are highly susceptible to cold burning, resulting in low storage periods at low temperatures. Plant extracts or essential oils (EOs) can potentially be used as preservatives in fruits throughout the refrigerated period. In the present study, the biochemicals, antioxidant characteristics, and shelf life of treated strawberries with Aloysia citrodora essential oil (ACEOs) were evaluated during keeping time. The treatments were produced as follows: T1, control; T2, 250 ppm ACEOs; T3, 500 ppm ACEOs; and T4, 750 ppm ACEOs. Total soluble solids (TSS), weight loss, titratable acidity (TA), antioxidant activity (DPPH assay), total phenolic (TPC), flavonoid and anthocyanin contents (TFC), and enzymes activity (peroxidase and ascorbate peroxidase) were evaluated during the refrigerated period (5 °C with relative humidity of 85-90% for 20 days). The results revealed that weight loss and TA were reduced in all treatments during storage, being that the rates were lower in samples treated with ACEOs. TPC, TFC, TSS, antioxidant, and enzymes activity were higher in treated fruits than control.

A Multivariate Analysis of the Composition and Properties of Extra Virgin Olive Oils Produced from Different Cultivars Grown in Iran.

The present study investigated variations in extra virgin olive oils in relation to fatty acid (FA) composition and the characteristics of 10 olive cultivars. The findings demonstrated that their oil yield properties, including refractive index, acid value, peroxide value, saponification value, iodine value, and composition, were significantly different. Moreover, based on GC-MS analysis, the presence of oleic acid [C18:1(9)] was identified as one of the major components. The highest amount of 18:1(9) was found in four major varieties of cultivars, namely Zard, Roghani, Karidolia, and Korfolia. Hierarchical cluster analysis of principal component analysis revealed two distinct categories of cultivars based on their FAs. The first category (cluster I), consisted of Arbequina, Karydolia, Roghani, and Zard cultivars, which can be considered cultivars with good commercial cultivation potential due to their high contents of unsaturated FAs and oil quantities produced.

Ultrasound-assisted extraction process of phenolic antioxidants from Olive leaves: a nutraceutical study using RSM and LC-ESI-DAD-MS.

In recent years, there has been an ever growing interest in finding new natural sources of food antioxidants. As a main fruit crop, olive is also valued due to its phenolic-containing leaves. Mathematically based optimization methods are used as powerful tools to extract different antioxidant compounds. The present study is aimed to provide an efficient extraction method for total phenol content (TPC), total flavonoid content (TFC) and antioxidant ability (DPPH scavenging assay and FRAP). The effects of ultrasonic temperature (35-65 °C), ultrasonic time (5-15 min), and ethanol to water ratio (Et: W) (25-75%) were evaluated. Second-order polynomial models were used through a rotatable Box-Behnken design (BBD) consisting of 15 experimental runs with three replicates at the center point. Interactional effects of the studied factors were significant in most cases for all responses. The highest extraction efficiency was found to be fifty-one percent of ethanol (65 °C, 15 min) to water ratio. Under optimal conditions, values for TPC, TFC, DPPHsc and FRAP assay were 183.4 (mg GAE. g-1 DW), 696.77 (mg Quercetin. g-1 DW), 78.98 (DPPHsc %) and 1942 µmol Fe+2/g DW, respectively. R2 values (R2 > 0.92) showed that RSM models could efficiently predict the yield of all responses. In the LC-ESI-MS-DAD profiling of the optimized extract, 27 compounds were identified with oleuropein as the main compound. In the present study, olive leaf is introduced as a promising source of natural antioxidant and can be used in food industries following further studies.