Effects of preharvest applications of chemicals and storage conditions on the physico-chemical characteristics and shelf life of tomato (Solanum lycopersicum L.) fruit.

The aim of this study was to investigate the influence of preharvest sprays of chemicals and evaporative cooling (ZECC) on the postharvest physico-chemical quality and shelf life of tomatoes. The experiment was conducted using a combination of ten preharvest sprays of chemicals (chitosan (0.1%), chitosan (0.3%), chitosan (0.5%), salicylic acid (SA) (0.015%), SA (0.03%), SA (0.045%), calcium chloride (CaCl2) (1%), CaCl2 (3%), CaCl2 (5%) and control) and two storage conditions (ambient environment storage and ZECC). The design of the experiment was completely randomized design with three replications. Data were collected from tomato samples (Solanum lycopersicum L. cv. ARP tomato D2) on four days interval. The result showed that all physico-chemical quality indicators were significantly (p ≤ 0.05) affected by both preharvest sprays and storage conditions. CaCl2 (5%) sprays extended the shelf life of tomato by 6 days in ZECC and 11 days in ambient storage compared to the control. The highest concentration of CaCl2 and SA sprays minimized PLW and maintained fruit marketability compared to the control. The firmness of tomatoes was better retained with the sprays of SA (0.045%) in both storage conditions. CaCl2 (5%), SA (0.045%) and chitosan (0.5%) sprays retained the titratable acidity by 42.86%, 47.62% and 33.33%, respectively compared to the control inside ZECC storage. At the end of storage period, the highest TSS was observed on tomatoes sprayed with SA (0.03%) followed by chitosan (0.1%) and chitosan (0.3%). The lycopene contents were lower with sprays of SA (0.045%), SA (0.03%), CaCl2 (3%), CaCl2 (5%) and chitosan (0.1%) stored inside ZECC indicating the effectiveness of preharvest sprays in delaying lycopene accumulation. Moreover, the AA contents of tomatoes sprayed with CaCl2 (5%), SA (0.045%) and chitosan (0.1%) were higher by 34.10%, 38.19% and 23.84%, respectively compared to the control. The result indicated that combining preharvest chemical sprays and ZECC storage is important to maintain the physico-chemical quality and shelf life of tomatoes.

Biogenic silver nanoparticles production and characterization from native stain of Corynebacterium species and its antimicrobial activity.

In the present study, synthesis, characterization, and the antibacterial activity of silver nanoparticles from native isolate of Corynebacterium glutamicum has been reported. Silver nanoparticles were synthesized by challenging the dried biomass of C. glutamicum with aqueous diamine silver ([Ag (NH3)2]+) containing 1 mM AgNO3. Synthesized silver nanoparticles (AgNPs) were characterized by ultraviolet-visible spectroscopy and energy-dispersive X-ray (EDX) spectroscopy analysis. Morphological study of silver nanoparticles was carried out using transmission electron microscopy (TEM) and scanning electron microscope (SEM). The spherical morphology of silver nanoparticles was confirmed from SEM image. The TEM image showed the average particle size of silver nanoparticles was about 15 nm. Silver nanoparticles synthesized from C. glutamicum were found to have enhanced antimicrobial activity against selected pathogenic strains. Silver nanoparticles from pure strains of Corynebacterium species was done by many investigators, but as per the present literature, this is the first report on the production of silver nanoparticles using a native strain of Corynebacterium.