Exporting avocado involves a number of postharvest problems because the fruit has a limited shelf life and marked sensitivity to development of chilling injury when using low temperatures to prolong its useful life. There are measures to alleviate the problem, such as infiltration of calcium ions; therefore, the aim of this study was to evaluate the effect of preharvest spraying of Ca(NO3)2, at 0.3 and 0.5 %, on the postharvest physiology of cv. Hass fruits stored at 5 °C and room temperature for five weeks. The sprayings were performed in the aerial part every six weeks until harvest, totaling six applications. The variables evaluated were: ethylene production, respiration rate, calcium concentration in the exocarp and mesocarp, firmness, polyphenol oxidase activity, weight loss and chilling injury. It was found that Ca(NO3)2, at 0.3 and 0.5 %, decreased the respiratory rate and ethylene production during storage at room temperature and under chilling conditions. An Increase in the calcium concentration in the exocarp (0.085 %) was observed when 0.5 % Ca(NO3)2 was sprayed, as compared to the control (0.08 %). In the mesocarp, concentrations of 0.081 % were reached by spraying Ca(NO3)2 at 0.3 % and 0.084 % with calcium at 0.5 %, values higher than those of the control (0.078 %). In general, the Ca(NO3)2 sprayings decreased weight loss, polyphenol oxidase activity and chilling injury.

The objectives of this research were: a) detect differences in leaf nutrient concentrations of various clonal avocado rootstocks prior to being grafted, and b) determine the effect of the rootstock on leaf nutrient concentrations in young and adult ‘Hass’ scions grown without irrigation. Rootstocks were planted in 2000 and grafted in 2001 in a rainfed orchard in the municipality of Tepic, Nayarit, Mexico. As control, ‘Hass’ on native rootstock grown from seed was used. Thirty six-month-old leaves from the winter vegetative flush were sampled from each tree and from them the concentration of macro- and micronutrients was determined. The ungrafted rootstocks and the young ‘Hass’ trees on the evaluated rootstocks showed no variations in leaf nutrient concentrations, and in adult trees there were only differences for P. Leaf concentrations of N, P, Ca, Mn and B were higher at the beginning of the productive stage of the trees, while nutrient concentrations of Fe and Zn were higher in trees in full production. The type of rootstock used did not affect fruit production. This research identified rootstocks that positively or negatively modify leaf nutrient concentrations in ‘Hass’ scions, which will help the commercial management of their nutrition.

Dahlias, in addition to their use as ornamental flowers, are consumed in a wide variety of foods. However, once harvested their shelf life is less than three days. The aim of this study was to evaluate the antimicrobial effect of 0.25 % cinnamaldehyde on edible dahlias held in polyethylene terephthalate (PET) and low-density polyethylene (LDPE) packages stored at 8 and 25 °C. Also, the ripening and quality of treated flowers were evaluated. The total population of yeasts and molds, mesophilic aerobic bacteria and psychrophilic bacteria increased during storage. Both packaging materials and cinnamaldehyde influenced the microbial count; however, microbial development was not totally controlled. The lowest weight loss was observed with PET, regardless of storage temperature. The lowest respiration rate was obtained in dahlias stored at 8 ° C, regardless of packaging material. Ethylene production was not influenced by packaging material or storage temperature. In general, phenolic compounds and antioxidant capacity remained unchanged during storage. However, further studies are needed to improve control of pathogenic microorganisms in this commodity.

Pitaya (Stenocereus pruinosus) is a columnar cactus that can be found in semi-arid regions. Fruit have deciduous thorns and shelf life is less than six days at ambient temperature, which limits commercialization. The objective of this study was to evaluate the postharvest behavior of pitaya fruit under refrigeration conditions and also to evaluate the effect of thorn removal on fruit quality attributes. Storage for 21 d at 12 °C was conducted with pitaya fruit of red and orange flesh, handled with or without thorns. Fruit weighed between 168.1 and 197.6 g, with respiration rate between 11.9 and 12.6 mL⋅kg-1 ⋅h-1 , and with soft consistency, expressed through firmness in flesh less than 2 N. Color attributes, total soluble solids (TSS), betalains and total soluble phenols (TSP) contents, and antioxidant activity were different between variants. Hue angle, chroma, and lightness in flesh were 22.0-25.0°, 29.0-31.0, and 22.8-23.8, respectively, in red fruit, and 35.5-37.7°, 38.9-41.5, and 29.7-32.6, in orange fruit. The TSS/acidity ratio was higher in orange (152.8-157.0) than in red (115.5-132.0) fruit. Betalains and TSP had average values of 4.7-423.0 and 2.5-221.6 mg⋅kg-1 in red and orange material, respectively, which caused higher antioxidant activity in the former. Betalains content remained constant over time, but TSP diminished and this caused a reduction in antioxidant activity. Thorn removal only affected weight loss and it was considered an advisable practice. Based on firmness modification and loss of antioxidant activity, shelf life was estimated to be 12-14 d.

The development of new postharvest technologies, which prolong useful fruit life and are also biodegradable, has promoted the use of edible coatings, prepared based on polysaccharides obtained from nonconventional sources, such as the starch and pectin in banana fruits. The objective of this study was to evaluate the effects of coatings based on starch and pectin from ‘Pear’ banana, as well as chitosan applied to ‘Ataulfo’ mango fruit. Coverings with 1 % starch and others with 1 % pectin were applied by immersion to mango fruits at physiological maturity; fruits were then stored for 12 days at 10 ± 2°C, plus another 9 days at 22 ± 2°C. The assessed variables were: weight loss (%), color (L*, a*, b*), firmness (kgf∙cm-2), total soluble solids (°Brix), and titratable acidity (%). ‘Ataulfo’ mango fruits covered with starch from ‘Pear’ banana (Musa ABB) showed greater firmness (3.34 kgf∙cm-2) and a high content of total soluble solids (16.96 °Brix), compared to the control fruits (2.26 kgf∙cm-2 and 15.8 °Brix, respectively); this coating extended the postharvest period to 21 days. The edible coatings did not affect the cuticle color of ‘Ataulfo’ mango fruits and retained their typical yellow color