Effect of maleic hydrazide and waxing on ripening and quality of guava (Psidium guajava L.) fruit

The effect of postharvest treatment by maleic hydrazide (MH) and waxing on ripening and quality of white and pink guava fruits was evaluated at 20 + 1OC and 85-90% relative humidity. MH at 250, 500 and 1000 ppm delayed fruit ripening by 2-6 days in both guava types compared to untreated fruits. The higher the concentration of MH, the more was the delay in fruit ripening. Waxing in addition to MH treatment resulted in 3-4 days more delay in fruit ripening, compared to MH treatment alone. The effect of MH treated and waxing in delaying fruit ripening was manifested in retarded climacteric peak of respiration, delayed peel colour development, reduced total soluble solids accumulation and decreased fruit softening

Effect of maleic hydrazide and waxing on ripening and quality of tomato fruit

       The effect of postharvest treatment of maleic hydrazide (MH) and waxing on ripening and quality of 'Stain-B' and 'UC-82' tomato fruits at 20 ± I0C and 85-90% RH was evaluated during 2002/2003 season. Maleic hydrazide at 100, 250 and 500 ppm delayed fruit ripening by one to three days in both tomato cultivars. The higher the concentration; the more the delay in fruit ripening. Waxing in addition to MH treatment resulted in 1-2 days more delay in fruit ripening, compared to MH treatment alone. The effect of MH treatment and waxing in delaying fruit ripening was in retarded respiratory climacteric, delayed colour development and total soluble solids (TSS) accumulation, decreased fruit softening, titratable acidity, phenolic content and weight loss, and retained ascorbic acid conten

Evaluation of alternative preservation treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomato

Previously optimised postharvest treatments were compared to conventional chlorinated water treatment in terms of their effects on the overall quality of tomato (‘Zinac’) during storage at 10 °C. The treatments in question were water heat treatment (WHT = 40 °C, 30 min), ultrasounds (US = 45 kHz, 80 %, 30 min), thermosonication (TS =40 °C, 30 min, 45 kHz, 80 %) and ultraviolet irradiation (UV-C: 0.97 kJ m−2). The quality factors evaluated were colour, texture, sensorial analysis, mass loss, antioxidant capacity, total phenolic content, peroxidase and pectin methylesterase enzymatic activities, and microbial load reduction. The results demonstrate that all treatments tested preserve tomato quality to some extent during storage at 10 °C. WHT, TS and UV-C proved to be more efficient on minimising colour and texture changes with the additional advantage of microbial load reduction, leading to a shelf life extension when compared to control trials. However, at the end of storage, with exception of WHT samples, the antioxidant activity and phenolic content of treated samples was lower than for control samples. Moreover, sensorial results were well correlated with instrumental colour experimental data. This study presents alternative postharvest technologies that improve tomato (Zinac) quality during shelf life period and minimise the negative impact of conventional chlorinated water on human safety, health and environment.info:eu-repo/semantics/publishedVersio

Structure and expression of an inhibitor of fungal polygalacturonases from tomato

Medline is the source for the MeSH terms of this document.A polygalacturonase inhibitor protein (PGIP) was characterized from tomato fruit. Differential glycosylation of a single polypeptide accounted for heterogeneity in concanavalin A binding and in molecular mass. Tomato PGIP had a native molecular mass of 35 to 41 kDa, a native isoelectric point of 9.0, and a chemically deglycosylated molecular mass of 34 kDa, suggesting shared structural similarities with pear fruit PGIP. When purified PGIPs from pear and tomato were compared, tomato PGIP was approximately twenty-fold less effective an inhibitor of polygalacturonase activity isolated from cultures of Botrytis cinerea. Based on partial amino acid sequence, polymerase chain reaction products and genomic clones were isolated and used to demonstrate the presence of PGIP mRNA in both immature and ripening fruit as well as cell suspension cultures. Nucleotide sequence analysis indicates that the gene, uninterrupted by introns, encodes a predicted 36.5 kDa polypeptide containing amino acid sequences determined from the purified protein and sharing 68% and 50% amino acid sequence identity with pear and bean PGIPs, respectively. Analysis of the PGIP sequences also revealed that they belong to a class of proteins which contain leucine-rich tandem repeats. Because these sequence domains have been associated with protein-protein interactions, it is possible that they contribute to the interaction between PGIP and fungal polygalacturonasesPeer reviewe