The maturity of two selections of soursop (G1 and G2) from Nayarit, Mexico, was evaluated under environmental conditions at 22°C and refrigeration at 15°C stored for 6 and 8 days, respectively. Maximum CO₂and ethylene values were present on the fifth and sixth day. The fruits exposed at 15°C had a significantly lower weight loss (5%) and showed no chilling injury. The firmness of two selections decreased more than 90%. The concentration of TSS increased to 5.3 to 15°Brix, and the titratable acidity was higher for fruit stored at 22°C. The highest concentration of phenols was recorded on the fourth day of storage at 22°C. The enzymatic activity of PPO was increased from physiological ripening to consumption ripening for both treatments. The two selections stored at 22°C registered the highest level of PME activity at ripeness. Shelf life was increased by up to 8 days (4 days at 15°C plus 4 days at 22°C) without causing chilling injury or alterations in the ripening process of the fruits. No significant differences were observed between the two selections evaluated; postharvest handling was considered to be similar; however, it would be advisable to evaluate other technologies combined with refrigeration.

Nayarit es el principal productor de guanábana (Annona muricata L.) a nivel mundial; sin embargo, no se reconocen variedades o ecotipos presentes en la entidad, la mayoría de la producción se realiza en árboles a pie franco. Así, se presentan resultados de una investigación preliminar sobre la caracterización de frutos de guanábana (Annona muricata L.) de Tepic, Nayarit. Se seleccionaron 13 árboles de ocho años de edad, de los cuales se cosecharon de cuatro a siete frutos entre junio y julio de 2014. La masa del fruto en la población varió entre 837.8 y 2513 g, la proporción promedio de pulpa, cascara y semilla fue de 71, 20.5 y 8.5%, respectivamente, en la población. Los frutos fueron elípticos en promedio, con un contenido de semillas entre 19 y 311. El color de la epidermis del fruto fue verde opaca y poco luminosa (h= 151.7 - 164.9, C*= 9.4-21.4; L*= 30.2 -45.8), la firmeza fue en promedio de 7.3 N, los sólidos solubles totales entre 7.1 y 14 °Brix, la acidez titulable promedio fue de 0.7 % y el pH de 3.6. El análisis de conglomerados formó 4 grupos. El grupo cuatro presentó el menor número de semillas (41) y mayor cantidad de SST (13.2 oBrix). Las variables masa, dimensiones y color de la cascara ayudaron a la separación de los grupos. Se determinó variabilidad en guanábana con potencial para obtener frutos para el mercado en fresco e industrial; así como para propagación de la especie.

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

Soursop (Annona muricata L.) is climacteric fruit with a short ripening period and postharvest shelf life, leading to a rapid softening. In this study, transcriptome analysis of soursop fruits was performed to identify key gene families involved in ripening under postharvest storage conditions (Day 0, Day 3 stored at 28 ± 2 °C, Day 6 at 28 ± 2 °C, Day 3 at 15 ± 2 °C, Day 6 at 15 ± 2 °C, Day 9 at 15 ± 2 °C). The transcriptome analysis showed 224,074 transcripts assembled clustering into 95, 832 unigenes, of which 21, 494 had ORF. RNA-seq analysis showed the highest number of differentially expressed genes on Day 9 at 15 ± 2 °C with 9291 genes (4772 up-regulated and 4519 down-regulated), recording the highest logarithmic fold change in pectin-related genes. Enrichment analysis presented significantly represented GO terms and KEGG pathways associated with molecular function, metabolic process, catalytic activity, biological process terms, as well as biosynthesis of secondary metabolites, plant hormone signal, starch, and sucrose metabolism, plant–pathogen interaction, plant–hormone signal transduction, and MAPK-signaling pathways, among others. Network analysis revealed that pectinesterase genes directly regulate the loss of firmness in fruits stored at 15 ± 2 °C.

The changes in concentration of vitamin C, enzymatic and antioxidant activity during the ripening of two soursop selections (G1 and G2) at room temperature (22 ºC) and refrigeration (15 ºC) with an HR 85% were evaluated. The content of soluble protein, the activity of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), the concentration of vitamin C, as well as the antioxidant activity was evaluated by DPPH, ABTS and FRAP methods. The initial soluble protein concentration of the G1 and G2 selections diminished at 22 and 15 °C during ripening. Fruits stored at 22 °C showed the highest CAT activity. The maximum activity of SOD was recorded on the sixth and fourth day in fruits stored at 22 and 15 ºC, respectively. Fruits stored at 22 °C recorded the highest amount of vitamin C. Fruits stored at 22 and 15 ºC showed the highest antioxidant activity on the fourth day. The fruits stored at 15 ºC was able to increase the shelf life up to 8 days without affecting the ripening process. Therefore, the enzymatic and antioxidant activity has an important role in the possible alteration that the fruit might suffer during its fruit ripening.

The soursop fruit (Annona muricataL.) is a crop of significant economic value for Nayarit, which is characterized by having a bittersweet taste, making it attractive to the consumer. However, the soursop has rapid maturation which causes a short shelf life. Several postharvest management techniques have been applied to reduce its metabolic processes, such as refrigeration, use of 1-methylcyclopropene (1-MCP), and controlled and modified atmospheres. In recent years, polysaccharide-based coatings have been applied to fruits. Therefore, the objective of this investigation was to evaluate the physicochemical and biochemical changes, as well as the antioxidant activity of soursop fruits with a mucilage-based coating (2%), stored at 22°C and 15°C with a 90% RH. Weight loss, firmness, color, soluble solids, acidity, pH, phenols, flavonoids, vitamin C, and antioxidant activity were evaluated. The results obtained in the coated fruits stored at 15°C showed lower weight loss (6.4%), lower firmness (29.7 N), higher TSS concentration (10.4°Bx), and lower acidity (0.38%) compared with the uncoated fruits. The total phenolic content decreased in coated fruits stored at 22°C (54.3 mg EGA/100 g FW). The highest antioxidant activity (DPPH method) was recorded in fruits coated and stored at 15°C with an average value of 257.9 mg EAA/100 g FW. Moreover, a high concentration of vitamin C was observed in fruits coated and stored at 15°C and 22°C (20.5 and 17.5 mg EAA/100 g FW), concluding that the coating based on roselle mucilage (2%) in combination with a temperature of 15°C prevents weight loss, decreases titratable acidity, and increases the content of phenols and vitamin C. Furthermore, an increase in the shelf life up to eight days and in the antioxidant activity at the maturity of consumption was observed in the fruits coated with 2% roselle mucilage stored at 15°C.