Antioxidant and anti-inflammatory properties of papaya (Carica papaya) fruits were evaluated to provide comprehensive information associated with the bioactive compounds. ‘Tainung No. 2’ papaya fruits, cultivated in a greenhouse, Korea, were harvested at unripe and ripe stages and then divided into seed and peel-pulp. Total phenolic and flavonoid contents were determined using spectrophotometry, and individual phenolic compounds were relatively quantified by HPLC-DAD and fifteen standards. Antioxidant activities were measured using four assays: DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) scavenging activities, inhibition of lipid peroxidation, and FRAP (ferric reducing antioxidant power). Anti-inflammatory activities were measured by the regulation of NF-κB signaling pathways with the measurements of ROS and NO productions as the degree of oxidative stress. Total phenol contents increased in seed and peel–pulp extracts during ripening; flavonoid contents increased only in seed extracts. Total phenolic contents were associated with ABTS radical scavenging activity and FRAP. Of fifteen phenolic compounds, chlorogenic acid, cynarin, eupatorine, neochlorogenic acid, and vicenin II were identified among papaya extracts. ROS and NO productions were inhibited in papaya extracts. Especially, NO productions were inhibited higher in ripe seed extracts than in other extracts, which would be associated with the suppression of NF-κB activation and iNOS expression. These results suggest that papaya fruit extracts, including seeds, peels, and pulps, could be potential raw materials for functional foods.

To investigate the effects of short-term low temperatures, three-year-old avocado (Persea americana cv. Hass) seedlings were treated with 1, − 2, or − 5 °C for 1 h and subsequently recovered in ambient condition for 24 h. Leaf color changes were investigated with chlorophyll, carotenoid, and phenolic contents. Photosynthetic responses were examined using gas exchange analysis. With H₂O₂ contents as oxidative stresses, enzymatic (ascorbate peroxidase, APX; glutathione reductase, GR; catalase, CAT; peroxidase, POD) and non-enzymatic antioxidant activities were determined using spectrophotometry. Leaves in the avocado seedlings started to be discolored with changes in the contents of chlorophyll a, carotenoids, and phenolics when treated with − 5 °C. However, the H₂O₂ content was not different in leaves treated with low temperatures. Photosynthetic activities decreased in leaves in the seedlings treated with − 5 °C. Of antioxidant enzymes, APX and GR have high activities in leaves in the seedlings treated with 1 and − 2 °C. In leaves in the seedlings treated with − 5 °C, the activities of all enzymes decreased. Non-enzymatic antioxidant activity was not different among leaves treated with low temperatures. These results indicated that APX and GR would play a critical role in withstanding chilling stress in ‘Hass’ avocado seedlings. However, under lethal temperature, even for a short time, the plants suffered irreversible damage with the breakdown of photosystem and antioxidant system.

Seolah Kim, Sun Woo Chung, Hyun Joo An, Chan Kyu Lim, Mi Kyoung Jeon, and Yeon Jin Jang. Journal of the Korean Society of Food Science and Nutrition 2022;51:344-51. https://doi.org/10.3746/jkfn.2022.51.4.344

Papaya fruit (Carica papaya) has different degrees of ripening within each fruit, affecting its commercial market value. The fruit characteristics of “Tainung No. 2” Red papaya were investigated at the stem-end, middle, and calyx-end across 3 ripening stages and categorized based on fruit skin coloration: unripe at 16 weeks after anthesis (WAA), half-ripe at 18 WAA, and full-ripe at 20 WAA. The fruits maintained an elliptical shape during ripening with a ratio of 2.36 of the length to the width. The peel and pulp color changed from green to white to yellow during ripening, regardless of the three parts. In the pulp, soluble solid contents increased, and firmness decreased during ripening but did not differ among the three parts. Individual nutrient contents, including metabolites and minerals, changed dynamically between the ripening stages and fruit parts. Total carbohydrates and proteins, N, and K, were accumulated more at the stem-end during ripening; meanwhile, fructose, glucose, Mg, and Mn were accumulated more at the calyx-end. In the principal component analysis, ripening stages and fruit parts were distinctly determined by the first and second principal components, respectively. Understanding the nutrient and metabolite dynamics during ripening and their distribution within the fruit can help optimize cultivation practices, enhance fruit quality, and ultimately benefit both growers and consumers.

The vegetative growth, photosynthetic, and stomatal characteristics were investigated in Phalaenopsis Queen Beer ‘Mantefon’ to determine light’s influence with calcium ammonium nitrate (CAN) levels under 800 μmol·mol⁻¹ CO₂. Two lights (150 ± 20 and 300 ± 20 μmol·m⁻²·s⁻¹) and CAN levels were employed for 40 weeks: calcium, ammonium, and nitrate levels by 0.90, 0.55, and 2.97 mmol·L⁻¹ (CAN1), 8.63, 1.11, and 6.05 mmol·L⁻¹ (CAN2), 12.80, 1.72, and 9.13 mmol·L⁻¹ (CAN3), and 18.80, 2.27, and 12.20 mmol·L⁻¹ (CAN4), respectively. The number of leaves increased in the plants grown at 300 ± 20 μmol·m⁻²·s⁻¹ with CAN1 compared to control. Plants grown at 300 ± 20 μmol·m⁻²·s⁻¹ with CAN4 had the lowest number of leaves among all plants. The time to the mature leaf span decreased in the plants grown at 300 ± 20 μmol·m⁻²·s⁻¹ with CAN1. The net CO₂ uptake was higher in the plants grown at 300 ± 20 μmol·m⁻²·s⁻¹ than those grown at 150 ± 20 μmol·m⁻²·s⁻¹ with CAN1–3 conditions. The water-use efficiency is higher in the plants grown with CAN1 than those with CAN2–4 at 300 ± 20 μmol·m⁻²·s⁻¹. The maximum stomatal aperture was the largest in the plants grown at 300 ± 20 μmol·m⁻²·s⁻¹ with CAN1–2 among all plants. Consequently, light levels of 300 ± 20 μmol·m⁻²·s⁻¹ in Phalaenopsis Queen Beer ‘Mantefon’ must be accompanied by nutrient CAN1 to improve photosynthesis and stomatal activity and promote leaf growth under 800 μmol·mol⁻¹ CO₂ conditions.