Determination of optimum maturity stage in mango (Mangifera indica L.) for fruit quality

Abstract

Mango (Mangifera indica L.), the national fruit of India is nutritionally rich in carbohydrates, proteins, vitamins and minerals such as calcium, iron, and phosphorus and hence known as the “King of fruits”. Mangoes are popular in markets worldwide because of unique flavour, appealing aroma, colour and taste (Arauz, 2000). In Indian subcontinent flowering of mango starts from November in Kerala and extends to February – March in Northern India. Mangoes from Kerala fetch higher price in the main markets at other parts of the country due to earliness. But commercial cultivation of mango in Kerala is limited to a few pockets in Palakkad district and the national varieties such as Alphonso, Banganapalli, Amrapali, Ratna and Mallika are occasional. The adaptation of different varieties to the climatic conditions prevailing fruiting and yielding behaviour of the varieties, production and post-harvest management practices followed by the growers, prevailing marketing system, are some of the problems of mango cultivation in Kerala. Mango fruits gain acceptance and popularity among consumers when it is served with the correct ripeness. Mangoes harvested at full maturity had a shorter shelf life, but those harvested early had a higher weight loss but improved storability (Shahjahan et al., 1994). Maturity standards in relation to the quality of important commercial varieties have not been studied when grown under humid tropical conditions of Kerala. Hence a study on the “Determination of optimum maturity stage in mango (Mangifera indica L.) for fruit quality” was carried out at the Department of Post-Harvest Technology, College of Agriculture, Vellanikkara, Thrissur, Kerala during 2019- 21 with the objective to find out the ideal harvesting stage of two important mango varieties viz. Ratna and Mallika for good organoleptic qualities and shelf life. The varieties of mango grown in the college orchard were utilized for the study. Flowers were tagged at the time of fruit set and observations on external appearance, peel, pulp colour, stone characters and biochemical changes were taken at 90, 100,110 120 and 140 days after fruit set (DAFS) as per the IPGRI descriptor. Heat unit requirements for maturity were also studied, for determining optimum days for maturity. In case of mango cv. Ratna, 90, 100 and 110 DAFS are the three stages of growth and in cv. Mallika, 90, 110,120 and 140 DAFS are four stages of growth. Physical and biochemical characters were studied at different stages of growth. In mango cv. Ratna fruits harvested 110 DAFS with accumulation of 1107.75 HU recorded good quality attributes. Fruits harvested at this stage had attractive length (10.44 cm), diameter (26.1 cm), weight (358.8 g), firmness (1.40 kg/cm2 ), specific gravity (1.03), stone length (7.49 cm), stone weight (10.68 g), TSS (21.12 ⁰brix), acidity (0.30 %), ascorbic acid (33.48 mg/100g), total sugar (19.04 %), total phenol (32.06 mg/100g), total carotenoid (14.65 mg/100g), β-carotene (0.88 mg/100g), crude fibre (2.59 %) and total chlorophyll (0.01 mg/100g) with a score of 8.00 in overall acceptability in sensory evaluation. In mango cv. Mallika fruits harvested 140 DAFS with accumulation of 1507.00 HU was found to be good in quality attributes. Fruits harvested 140 DAFS had good length (14.80 cm), diameter (28.03 cm), weight (623.95 g), firmness (0.73 kg/cm2 ), specific gravity (1.05), stone length (11.83 cm), stone diameter (12.63 cm), stone weight (66.73 g), TSS (20.18 ⁰brix), acidity (0.73%), ascorbic acid (61.21 mg/100g), total sugar (17.00 %), total phenol (47.5 mg/100g), total carotenoid (7.56 mg/100g), β-carotene (0.03 mg/100g), crude fibre (3.44 %) and total chlorophyll (0.01 mg/100g) with a score of 8.25 in overall acceptability in sensory evaluation. Study on effect of maturity on ripening was done in the variety cv. Ratna at their mature stage. Fruits harvested at the optimum maturity stage (100 DAFS) and ten days prior to maturity stage (90 DAFS) were kept for ripening after giving five different pre-treatments, viz., control (T1), ethrel spray (T2), hot water dip with ethrel spray (T3), sanitization with ethrel spray (T4) and ozonisation with ethrel spray (T5). Treated fruits packed in ventilated CFB boxes were kept under ambient condition and observations were recorded at 3 days interval. PLW increased with increase in storage period resulted in decrease in shelf life because of more loss in weight but the TSS and sugar increased however storability was less. High ethylene evolution on 3 days after storage indicates that it is tending towards maturity and it lowers after 6 days of storage resulting in complete ripened stage. Thus it can be concluded that the fruits of mango cv. Ratna harvested 10 and 20 days prior to ripe mature stage can be stored for 6 days under ambient conditions after giving pre-treatment consisting of Ozonization @ 200 ppm and ethrel spray @ 200 ppm.