Karthikeyan Venkatachalam | Prince of Songkla University (original) (raw)

Uploads

Papers by Karthikeyan Venkatachalam

Introduction. Longkong (Aglaia dookkoo Griff.) fruit is a non-climacteric tropical fruit and grow... more Introduction. Longkong (Aglaia dookkoo Griff.) fruit is a non-climacteric tropical fruit and grows widely in the South-East Asia. It has a unique taste and nutritional properties that make it more valuable to export. However, longkong exhibits a shorter shelf life at ambient (25 °C for 3−5 days) and low temperature (13 °C for 10 days) storage. Therefore, there is an urgent need to extend its shelf life and marketability by using an inexpensive and proficient technique. Materials and methods. Methyl jasmonate (MeJA) treatments with different concentrations (10, 20 and 30 μMol L-1) were used to control physiological and biochemical quality changes of longkong fruit stored at 13 °C and 85% relative humidity. Fruit with no MeJA treatment served as control. The physiological and biochemical quality analyses were carried out at every four days of the interval. Results and discussion. Longkong pericarp chilling injury (CI) index and ion leakage severely increased in the control fruits as compared with MeJA treated fruit. The increased of pericarp phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities were well controlled by MeJA treatments. Fruit polygalacturonase (PG), pectin methyl esterase (PME) and lipoxygenase (LOX) activities were significantly controlled in MeJA treated fruit. Fruit superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities found higher level in the MeJA treated fruit. Conclusion. The different concentrations of MeJA treatment effectively reduced the severity of physiological and biochemical quality changes in longkong fruit under prolonged low temperature storage.

Longkong has a short shelf life (3 to 5 days) at ambient temperature due to its pericarp browning... more Longkong has a short shelf life (3 to 5 days) at ambient temperature due to its pericarp browning and biochemical quality loss. The present study investigated the quality changes of longkong fruit during storage under passive modified atmospheric packaging (MAP) at ambient temperature (25 ºC and at 85 % relative humidity). Fruit stored without MAP served as a control. The accumulation of headspace gas (% CO2) in the fruit package was observed less than 65 % during all over the storage. The increase of fruit weight loss was effectively controlled in passive MAP storage than the control. Passive MAP storage
maintained the lowest browning index values as compared to the control during storage. Throughout the
storage, pericarp phenylanine ammonia lyase, polyphenol oxidase and peroxidase had higher activities in
the control fruits. The significant changes in fruit pH, titratable acidity (TA), total soluble solids (TSS) and TSS/TA content were observed in both the control and passive MAP during the storage. Fruits stored under passive MAP had more scavenging ability than reducing power during storage. However, due to
lower surface mould growth, the passive MAP stored longkong had a quality and shelf life of up to 12 days at ambient temperature.

Longkong is a non-climacteric tropical fruit with short shelf life at ambient temperature. Howeve... more Longkong is a non-climacteric tropical fruit with short shelf life at ambient temperature. However, lowtemperature storage can cause chilling injury (pericarp browning) which is unacceptable to consumers. Therefore, the objective of this experiment was to investigate the influence of fumigating longkongs with 10, 20 or
30 μmol/l methyl jasmonate (MeJA) at 25oC for 24 h on the alleviation of chilling injury during subsequent storage.
Both fumigated and non-fumigated (control) fruit samples were stored at 13oC and 85% RH. It was found that the
pericarp lightness and yellowness were decreased whereas the pericarp redness was increased continuously throughout the storage period of 16 days. However, the control sample had an extreme change in pericarp color (p<0.05). Pericarp phenolics content was decreased during storage and the control had the highest level of these compounds (70.87 mg gallic acid equivalent/100 g, p<0.05). The enzymes involved in pericarp browning such as phenylalanine ammonia lyase, polyphenol oxidase and peroxidase had low activities in the MeJA-treated fruit samples while in the control, the activities of these enzymes increased with increasing chilling injury (p<0.05).
Keywords: longkong, methyl jasmonate, chilling injury

: Longkong is a tropical and non-climacteric fruit which is highly perishable after harvest. The ... more : Longkong is a tropical and non-climacteric fruit which is highly perishable after harvest. The shelf life extension of longkong by using passive MAP with two different OTR packages and stored at 18ºC, 25ºC and at a 85% of relative humidity was investigated. In this study, physical and chemical quality changes of
longkong was monitored. At the end of storage longkong stored under 18ºC in M1 and M2 package was found better quality than other storage conditions and it resulted, less reduction in colour in both L* and b* values, less accumulation of CO2
, weight loss and also less reduction in pH, titratable acidity and sugar was found. Although, fruit stored in M1 had a better quality than M2, it evidenced by in L* (56.69), a* (10.55) and b*
(32.64) values. Weight loss was 2.61% and TSS was 14.2º Brix found at the end of storage.

The objective of this present study was to analyse and compare the total antioxidant activityand ... more The objective of this present study was to analyse and compare the total antioxidant activityand radical scavenging capacity of selected fruits and vegetables from south India. The selected
fruits and vegetables such as mulberries, papaya, red grapes, mango, guava, tomato, red onion,
red cauliflower, carrot and beetroot were used in this study. The selected fruits and vegetables showed a high variation in content of total ascorbic acid (ranged from 10.83 to 68.71 mg/100 g fresh weight (FW)); total phenolics (ranged from 26.57 to 57.64 mg/ 100 g FW) and total
flavonoids (ranged from 2.49 to 12.69 mg/100 g FW). Total antioxidant capacity of the selected
fruits and vegetables were ranged from 31.21 to 61.11 mg/100 g FW. The higher levels of radical scavenging capacity were observed in beetroot, red onion, red cauliflower, red grapes
and mulberries as compared to other fruits and vegetables (P < 0.05). Papaya and guava had moderate levels of radical scavenging capacity (P < 0.05). On the other hand, mango and tomato obtained low levels of radical scavenging capacity (P < 0.05). The overall, pigmented fruits and vegetables in this study contained the higher levels of antioxidant and radical scavenging capacity.

Food Chemistry

The optimum harvesting period of longkong from 13 to 16 weeks of maturation were used to analyse ... more The optimum harvesting period of longkong from 13 to 16 weeks of maturation were used to analyse the changes in physiochemical and browning related enzymes. The colour, such as lightness (L ⁄ ) and yellowness (b ⁄ ) decreased and conversely redness (a ⁄ ) increased. The fruit weight was significantly increased from 21.21 to 24.93 g and the diameter was also increased (p > 0.05). Chemical qualities, such as total soluble solids, pH, total sugar and reducing sugar increased while titratable acidity decreased at the end of maturation period (p < 0.05). The antioxidant activity, such as 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (from 4.73 to 8.97 mg/100 g), ferric reducing antioxidant power (from 5.06 to 6.83 mg/ 100 g) and total phenolic content increased (from 42.65 to 58.71 mg/100 g) (p < 0.05). The polyphenol oxidase activity significantly increased throughout the maturation; peroxidase and phenyl alanine ammonia lyase enzymes increased at the beginning but after that they decreased at the end of the maturation period. Peel epidermal trichomes losses on the surface and parenchyma cell changes in the cross section were found during these stages.

Background: Longkong fruit is one of the well-known tropical fruits in the South East Asia and wi... more Background: Longkong fruit is one of the well-known tropical fruits in the South East Asia and widely produces in the southern region of Thailand. Its unique taste, aroma, nutritional and medicinal properties increase the export values to several continents. However, the shelf life of longkong fruit is not sustainable (3-5 days) at ambient temperature due to pericarp browning and quality loss. Objective: The present study, fruits stored in polyethylene (PE) package at 18ºC (treatment) and at 70% relative humidity (RH) were used to sustain the shelf life and quality. The fruits stored without package at 18 and 25ºC (70% RH) were served as the controls. Results: Fruits stored in PE package were effectively minimized the respiration rate than the controls. The higher activities of pericarp phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) were seen in the controls and thus, severely increased their pericarp browning than treatment. The increased in fruit weight loss was highly limited in the treatment. The severe loss in fruits titratable acidity and total soluble solids were observed in the controls. Conclusion: However, the treatment was extended the fruits shelf life for up to 24 days as compared to the controls in which the shelf life was limited to 15 (18ºC) and 6 (25ºC) days, and it mainly due to the mould growth and severe pericarp browning.

Food Chemistry