Influence of Artichoke Antioxidant Activity in Their Susceptibility to Suffer Frost Injury.

In the northern hemisphere countries, artichoke harvest occurs in winter months; consequently, they are exposed to cold temperatures. This can lead to frost injury, such as triggering the blistering of the cuticle and detachment of outer bracts, which eventually could display brown or black discolouration. This can cause major economic and production losses. As far as we know, no literature is available about this problem in artichokes. Thus, the main aim of this study was to evaluate the effect of total phenolic content and the antioxidant potential of 'Blanca de Tudela' artichokes in their capacity to tolerate frost injury when they are exposed to low temperatures. Several factors were analysed, including floral head order, weight and size of artichokes, total phenolic content, phenolic profile and total antioxidant activity. Results showed that tertiary heads, which are the smallest in size, exhibited a greater amount of total phenolic content and antioxidant activity. As a result, these characteristics offered enhanced protection to the artichoke against frosting temperatures. In contrast, the largest artichokes, especially the primary heads, were more susceptible to suffer frostbite. Therefore, artichokes with robust antioxidant systems, characterized by elevated phenolic content, are crucial to reduce their susceptibility to frost injury.

The Influence of Flower Head Order and Gibberellic Acid Treatment on the Hydroxycinnamic Acid and Luteolin Derivatives Content in Globe Artichoke Cultivars.

Flower head orders and the use of GA3 (gibberellic acid) treatment could be two influencing factors determining the bioactive compound levels in artichoke, but little to no information is available about their effects. In this study, we have therefore evaluated the influence of these factors on the hydroxycinnamic acid and luteolin derivative levels in three categories of artichoke: Seed-propagated open-pollinated cultivars; vegetatively propagated cultivars; and seed-propagated hybrids. The hydroxycinnamic acids and luteolin derivatives were quantified by RP-HPLC-DAD. The average flower head weight was the lowest in tertiary heads and GA3-treated artichokes, followed by secondary and main heads. Moreover, the hydroxycinnamic acid and luteolin derivatives levels were significantly higher in tertiary heads than in secondary or main heads. In addition, the GA3 treatment significantly reduced the hydroxycinnamic acid content and, in contrast, improved luteolin derivatives levels. These effects depended on the flower head order and cultivar. Knowledge of the effects of flower head order and GA3 treatment is therefore key in order to achieve the greatest health-benefits from artichoke consumption.

Preharvest Treatment with Oxalic Acid Improves Postharvest Storage of Lemon Fruit by Stimulation of the Antioxidant System and Phenolic Content.

Lemon trees (Citrus limon (L.) Burm. F) were treated monthly with oxalic acid (OA) at 0.1, 0.5, and 1 mM from initial fruit growth on the tree until harvest in2019. The experiment was repeated in 2020, with the application of OA 1 mM (according to the best results of 2019). In both years, fruit from OA-treated trees and the controls were stored for 35 days at 10 °C. Results showed that all treatments reduced weight loss (WL) and maintained higher firmness, total soluble solids (TSS), and total acidity (TA) than in the controls. Meanwhile, colour (hue angle) did not show significant differences. The activity of antioxidant enzymes, catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) in the flavedo of the fruit from the OA-treated trees was higher than in the controls at harvest and after 35 days of storage. Similarly, the total phenolic content (TPC) in the flavedo and juice of the fruit from the OA-treated trees were higher than in the controls. The increase in the activity of the antioxidant enzymes and TPC started with the first preharvest OA treatment and were maintained during fruit development on the tree until harvest. Preharvest OA treatments enhanced the antioxidant system of the lemon fruits, reducing the postharvest incidence of decay. Thus, OA could be a useful tool to increase the quality and functional properties of lemon fruits.

Thymol Encapsulated into HP-ß-Cyclodextrin as an Alternative to Synthetic Fungicides to Induce Lemon Resistance against Sour Rot Decay.

Consumers demand the use of eco-friendly fungicides to treat fruit and vegetables and governmental authorities have unauthorized the application of chemical antifungals for the efficient control of sour rot. In the present research, the microwave irradiation (MW) method was used to encapsulate thymol into 2-hydroxylpropyl-beta-cyclodextrin (HP-ß-CD) and the effect of these HP-ß-CD on controlling sour rot in citrus fruit, caused by Geotrichum citri-aurantii, was evaluated. Amounts of 25 and 50 mM of HP-ß-CD-thymol were used, and compared with propiconazole, to control the decay of inoculated lemon fruit. The treatments were performed in curative and preventive experiments. The incidence and severity of Geotrichum citri-aurantii in 25 and 50 mM HP-ß-CD-thymol-treated fruit were reduced in both experiments. The preventive 50 mM HP-ß-CD-thymol treatment showed the best effect, reducing the sour rot, respiration rate and fruit weight loss during storage at 20 °C. HP-ß-CD-thymol increased polyphenol concentration and the activity of antioxidant enzymes, such as catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) in lemon peel, and the highest effects were found with the 50-mM dose. In conclusion, the results show that the use of thymol encapsulated by MW into HP-ß-CD could be an effective and sustainable tool, a substitute to the synthetic fungicides, for G. citri-auriantii control in citrus fruit.

Effect of Thymol and Carvacrol Encapsulated in Hp-Β-Cyclodextrin by Two Inclusion Methods against Geotrichum citri-aurantii.

Geotrichum citri-aurantii causes sour rot in citrus fruits and is responsible for important economic losses during storage. However, the availability of chemical fungicides for the control of this pathogen is limited. Thus, the aim of this research was to evaluate the antifungal efficacy of thymol and carvacrol encapsulated in 2-hydroxylpropyl-beta-cyclodextrin (HP-ß-CD) (prepared by the microwave irradiation method [MW] and solubility method [S]) for inhibition of G. citri-aurantii using in vitro bioassays broth (micro and macrodilutions methods) and inoculated food testing. Both encapsulated thymol and carvacrol were shown to be effective for inhibiting G. citri-aurantii growth in in vitro assays. Thymol was more effective in inhibiting G. citri-aurantii, while better encapsulation was provided by MW. HP-ß-CD-thymol encapsulated by MW (HP-ß-CD-thymol-MW) showed the lowest 50% effective dose (ED50 = 1.16 mM), minimum inhibitory concentration (MIC = 5.06 mM), and minimum fungicide concentration (MFC = 52.6 mM). HP-ß-CD-thymol-MW was found highly effective in reducing the growth rate and mycelial growth inhibition. Finally, HP-ß-CD-thymol-MW and HP-ß-CD-carvacrol-MW showed a higher persistent effect than thymol and carvacrol in their natural form in inhibiting this fungus. Therefore, HP-ß-CD-thymol-MW could be a promising alternative to synthetic fungicides for controlling G. citri-aurantii, the causal agent of citrus sour rot. PRACTICAL APPLICATION: Encapsulated thymol and carvacrol in HP-ß-Cyclodextrins are effective for controlling G. citri-aurantii in in vitro experiments. Encapsulation of thymol and carvacrol by microwave irradiation method (MW) was more effective than the solubility (S) method. Thymol was more effective than carvacrol, and the best results on G. citri-auriantii inhibition were achieved using the HP-ß-CD-thymol-MW method (which gave the lowest ED50 , MIC, and MFC).

Preharvest Application of Methyl Jasmonate as an Elicitor Improves the Yield and Phenolic Content of Artichoke.

The effects of methyl jasmonate (MeJa) treatment as an elicitor of artichoke plants [Cynara cardunculus var. scolymus (L.) Fiori] on the yield and quality attributes of artichokes, especially those related to individual phenolic content and antioxidant activity, at two harvest dates and along storage were analyzed in this research. Plants treated gave a higher yield of artichokes in comparison to control plants, with 0.55 kg more per plant. MeJa treatment also increased artichoke quality and phenolic content in the edible fraction at harvest and during storage at 2 °C for 28 days as a result of the accumulation of hydroxycinnamic acids and luteolin derivatives. In addition, antioxidant activity was enhanced by MeJa treatment and correlated with the total phenolic content. Results suggest that MeJa foliar application could be a simple and practical tool to improve the yield and phytochemical content on artichokes, with elicitation being a cheap and environmentally friendly procedure to improve the health-beneficial effects of artichoke consumption.

Preharvest application of oxalic acid improves quality and phytochemical content of artichoke (Cynara scolymus L.) at harvest and during storage.

In this study the effect of oxalic acid (OA) treatment of artichoke plants (Cynara scolymus L.) on head artichoke development and on artichokes quality parameters (weight loss, firmness, and color), respiration rate, antioxidant activity and phenolics (measured by Folin Ciocalteu and HPLC-DAD-ESI/MSn) at harvest and during storage for 21days at 2°C was evaluated. OA treatment increased the percentage of the first class artichokes although no significant effect was found in artichoke developmental process. OA-treatment reduced the respiration rate of artichokes and led to higher total hydrosoluble antioxidant activity and total phenolics and hydroxycinnamics and luteolins concentration both at harvest and during cold storage. In addition, luteolin 7-O-glucuronide 3-O-glucoside was identified for the first time in artichoke. Thus, it can be concluded that OA preharvest treatment could be a natural and useful tool to delay the artichoke postharvest senescence and improve the reported health-beneficial properties of artichokes consumption.

Preharvest application of oxalic acid increased fruit size, bioactive compounds, and antioxidant capacity in sweet cherry cultivars (Prunus avium L.).

Trees of 'Sweet Heart' and 'Sweet Late' sweet cherry cultivars (Prunus avium L.) were treated with oxalic acid (OA) at 0.5, 1.0, and 2.0 mM at 98, 112, and 126 days after full blossom. Results showed that all treatments increased fruit size at harvest, manifested by higher fruit volume and weight in cherries from treated trees than from controls, the higher effect being found with 2.0 mM OA (18 and 30% higher weight for 'Sweet Heart' and 'Sweet Late', respectively). Other quality parameters, such as color and firmness, were also increased by OA treatments, although no significant differences were found in total soluble solids or total acidity, showing that OA treatments did not affect the on-tree ripening process of sweet cherry. However, the increases in total anthocyanins, total phenolics, and antioxidant activity associated with the ripening process were higher in treated than in control cherries, leading to fruit with high bioactive compounds and antioxidant potential at commercial harvest (≅45% more anthocyanins and ≅20% more total phenolics). In addition, individual anthocyanins, flavonols, and chlorogenic acid derivatives were also increased by OA treatment. Thus, OA preharvest treatments could be an efficient and natural way to increase the quality and functional properties of sweet cherries.

Quality parameters and antioxidant properties in organic and conventionally grown broccoli after pre-storage hot water treatment.

BACKGROUND: Demand for broccoli has increased due to its high content of bioactive compounds. However, broccoli is a perishable commodity with a short shelf life mainly due to dehydration, yellowing and losses of bioactive compounds. Thus, efficient treatments to preserve broccoli quality are needed. RESULTS: The effect of heat treatment on senescence and antioxidant compounds evolution during storage at 20 °C was evaluated in organic and conventionally grown broccoli. Senescence evolved quickly as manifested by floral head yellowing, which was higher in conventional than in organic broccolis, but senescence was significantly delayed by heat treatment. All organic acids, including ascorbic acid, were found at higher concentrations in organic than in conventional broccoli at harvest but decreased during storage in all broccolis. Phenolic concentration and antioxidant activity (in both hydrophilic and lipophilic fractions) also decreased during storage, although these decreases were higher in conventional than in organic broccolis, and no differences were found attributable to heat treatment. CONCLUSIONS: Heat treatment was effective in delaying broccoli senescence, manifested by chlorophyll retention. In addition, organic broccoli maintained higher concentrations of bioactive compounds (ascorbic acid and phenolics) and antioxidant potential during storage than conventional broccoli, with higher potential health beneficial effects.

Postharvest treatments with salicylic acid, acetylsalicylic acid or oxalic acid delayed ripening and enhanced bioactive compounds and antioxidant capacity in sweet cherry.

Sweet cherry cultivars ('Cristalina' and 'Prime Giant') harvested at commercial ripening stage were treated with salicylic acid (SA), acetylsalicylic acid (ASA) or oxalic acid (OA) at 1 mM and then stored for 20 days under cold temperature. Results showed that all treatments delayed the postharvest ripening process, manifested by lower acidity, color changes and firmness losses, and maintained quality attributes for longer periods than controls. In addition, total phenolics, anthocyanins and antioxidant activity increased in untreated fruit during the first 10 days of storage and then decreased, while in fruits of all treatments, these parameters increased continuously during storage without significant differences among treatments. Thus, postharvest treatments with natural compounds, such as SA, ASA or OA, could be innovative tools to extend the storability of sweet cherry with higher content of bioactive compounds and antioxidant activity as compared with control fruits.

Maturity stage at harvest determines the fruit quality and antioxidant potential after storage of sweet cherry cultivars.

Eleven sweet cherry cultivars were harvested at three maturity stages (S1 to S3) based on skin color and stored at 2 degrees C for 16 days and a further period of 2 days at 20 degrees C (shelf life, SL) to analyze quality (color, total soluble solids, and total acidity) and bioactive compounds (total phenolics and anthocyanins) and their relationship to total antioxidant activity (TAA), determined in hydrophilic (H-TAA) or lipophilic (L-TAA) fraction. For all cultivars and maturity stages, the ripening process advanced during postharvest storage with increases in color intensity and decreases in acidity, as well as enhancements in phenolics, anthocyanins, and TAA in both H-TAA and L-TAA, although important differences existed among cultivars. The results showed that sweet cherry should be harvested at stage S3 (4 days later than the commercial harvest date) since after 16 days of cold storage + SL, the highest antioxidant capacity was achieved for both H-TAA and L-TAA.