Bitter apple or tumba (Citrullus colocynthis L.) is a prostrate annual herb belonging to the Cucurbitaceae family. It is highly tolerant against multiple abiotic stresses like drought, heat, and soil salinity and can easily grow on very marginal soil, even on sand dunes in hot, arid regions. Tumba fruit is a fleshy berry 5–10 cm in diameter and of a pale yellow color at ripening. The tumba fruit used in this research was harvested from the ICAR-CIAH, Bikaner research farm. The seeds were separated, and their oil was extracted to analyze its physical characteristics and composition (phytochemical compounds, fatty acid profile, etc.). The seeds of the tumba fruit contained 23–25% golden-yellow-colored oil with a specific gravity of 0.92 g/mL. The extracted oil contained appreciable amounts of phytochemical (bioactive) compounds like phenolics (5.39 mg GAE/100 g), flavonoids (938 mg catechin eq./100 g), carotenoids (79.5 mg/kg), oryzanol (0.066%), and lignans (0.012%), along with 70–122 mg AAE/100 g total antioxidant activity (depending on the determination method). The results of fatty acid profiling carried out by GC-MS/MS demonstrated that tumba seed oil contained about 70% unsaturated fatty acids with more than 51% polyunsaturated fatty acids. It mainly contained linoleic acid (C18:2n6; 50.3%), followed by oleic acid (C18:1n9; 18.0%), stearic acid (C18:0; 15.2%), and palmitic acid (C16:0; 12.4%). Therefore, this oil can be considered as a very good source of essential fatty acids like omega-6 fatty acid (linoleic acid), whereas it contains a lower concentration of omega-3 fatty acids (α-linolenic acid) and hydroxy polyunsaturated fatty acids. In addition, it also contains some odd chain fatty acids like pentadecanoic and heptadecanoic acid (C15:0 and C17:0, respectively), which have recently been demonstrated to be bioactive compounds in reducing the risk of cardiometabolic diseases. The results of this study suggest that tumba seed oil contains several health-promoting bioactive compounds with nutraceutical properties; hence, it can be an excellent dietary source.

The investigation was carried out to assess the effect of post-harvest dipping of minimally processed fresh cut lettuce with various concentrations (10, 100 and 1000 μmolL-1) of melatonin on shelf-life and sensory quality of lettuce stored at 6±2ºC for 8 days. Melatonin treatment was found effective in maintaining freshness and sensory quality of lettuce during storage. Browning was reduced by 45% and visual quality index increased by 44.10% compared to control in 100 μmol L-1 melatonin treated samples on the 6th day of storage. Maximum total chlorophyll, total phenol and total antioxidants and least activity of browning related enzyme i.e., peroxidase (POD) was observed in 100 μmol L-1 melatonin treated samples during storage. No significant variation was observed between 10 μmol L-1 melatonin treated and control samples. Browning index value had significant negative correlation with total chlorophyll, total phenol and total antioxidants whereas POD activity had significant positive correlation. It can be inferred from the present investigation that post-harvest treatment of 100 μmol L-1 melatonin extended shelf-life of minimally processed lettuce for 6 days by preserving phenols, chlorophyll, antioxidants and inhibiting POD activity.

The investigation was carried out to assess the effect of post-harvest dip treatment of melatonin (10, 100 and 1000 μmol L⁻¹) on shelf life and sensory qualities of minimally processed fresh cut lettuce, kept at 6±2ºC for 8 days. Melatonin treatment was found effective in maintaining freshness and sensory qualities of lettuce during storage. Browning was reduced by 45% with 44.10% higher visual quality index in 100 μmol L⁻¹ melatonin treated samples than control on the 6^th day of storage. Maximum total chlorophyll, phenol and antioxidants, with least activity of browning related enzyme i.e. peroxidase (POD) was also observed in 100 μmol L⁻¹ melatonin treated samples during the course of storage period. No significant variation was observed between melatonin @ 10 μmol L⁻¹ treated and control samples. Browning index value had significant negative correlation with total chlorophyll, phenol and antioxidants whereas POD activity had significant positive correlation. It can be inferred from the present investigation that post harvest treatment of 100 μmol L⁻¹ melatonin maintained the quality of minimally processed lettuce for 6 days storage at 6±2ºC temperature.