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Biochemical changes during post harvest storage of pummelo

•
•
M
MANDEEP KAUR

The three main points are: 1. Pummelo is a large citrus fruit known for its good flavor and juicy texture. It contains important nutrients like vitamin C, potassium, and folic acid. 2. Unlike climacteric fruits, the respiration rate of pummelo does not increase after harvesting since it is a non-climacteric fruit. Biochemical changes during ripening include a decrease in chlorophyll and increase in carotenoids, softening from pectin degradation, and development of flavor compounds. 3. As pummelo ripens and during post-harvest storage, there are changes in nutrients and compounds like ascorbic acid, phenols, flavonoids,

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Biochemical changes during post harvest storage of pummelo Submitted to: Dr Monica Sachdeva Taggar Assistant Biochemist Submitted by: Mandeep Kaur
Introduction to Pummelo Pummelo (Citrus grandis) is one of the largest citrus fruits. The fruit flesh is normally consumed rather than processing it into a juice. It is renowned for its good flavor and juicy texture. In addition, it’s flesh contains important nutrients including vitamin C, potassium, pectin, natural folic acid and chromium. Local NRCC Pummelo - 2 PTF - 4
Physio-biochemical changes in harvested pummelo fruit Respiration rate varies with the state of maturity and ripening in many fruits. The rate increasing to a maximum just prior to full ripening the phase called the climacteric. Citrus spp. (orange, acid lime, lemon, grapefruit and pummelo) are non-climacteric fruits. The respiration rate does not accelerate after harvesting. Non-climacteric fruits are best when ripened before harvesting.
Non – Climacteric Fruit Ripening Fig: Growth, respiration and ethylene production in non-climacteric fruits (Wills, 2007)
Ke D, 1993; Yang and Hoffman1984 Ethylene Biosynthesis & Ripening
Changes in Chlorophyll content
Synthesis of carotenoids & anthocyanin The colour change from green to orange or red in many fruits is due to the loss in chlorophyll and synthesis of carotenoids. Carotenes (hydrocarbons) Xanthophylls (their oxidized derivatives : hydroxy, oxy and epoxy compounds).
Increase in activity of enzymes Softening of fruits during ripening is due to degradation of pectin by pectinase like pectinase, polymethyl galacturonases, polygalacturonases, pectin esterase, pectin lyase.
Starch hydrolysis As the fruit maturity progresses, the starch reserves get hydrolysed into sugars (glucose, fructose or sucrose). Further the complex sugars viz. sucrose are broken down into simple sugars viz. glucose and fructose with the catalytic action of enzyme invertase.
Flavour/aroma compounds The flavour consists of basically three components viz. aroma, taste and mouth feel. The major flavouring compounds identified are esters, alcohols, aldehydes, acids and ketones. Product Flavour Grape fruit Nootakatone Lemon Citral Citral
Volatile Compounds & Aroma Profiles Pink and white pummelo fruit contained similar volatiles, which mainly consisted of limonene, cis-β-ocimene, α-terpinene, linalool, methyl anthranilate, and indole. Volatiles originate from proteins, carbohydrates, lipids, and vitamins. Their primary difference was in the concentration ratio between limonene and linalool. Major volatiles in pummelo peels were terpene hydrocarbons. Pink pummelo peel contained higher levels of aldehydes (e.g. octanal, decanal and citral). Whereas some trace-level important compounds (e.g. β-sinensal, α- sinensal and nootkatone) were found only in white pomelo peel.
Ascorbic acid/ vitamin C L-ascorbic acid (Vitamin C) is the naturally occurring ascorbic acid in fruits. A gradual rise in ascorbic acid content with fruit growth has been observed and the levels decline with the advancement of maturity and onset of fruit ripening and postharvest handling. It is found to be low at the time of harvest. The upsurge in ascorbic acid content during ripening of certain fruits could be due to increased lipid peroxidation, since fruit ripening is considered as an oxidative phenomenon necessitating the turnover of active oxygen species. The decrease in vitamin C during the later stages of ripening might be due to its oxidation to dehydroascorbic acid. The ascorbic acid content of pummelo fruits ranged from 37.70 to 84.49 mg/100ml juice.
Fig. Changes in total phenols (TP) (A) and total ascorbic acid (TAA) (B) in juice sacs of HR, BR and HuR during postharvest storage.
Phenols and flavonoids During ripening, there is a gradual change in certain secondary metabolites with the commencement of phenolic pathways. The newly synthesized phenolic compounds play a crucial role in the fruit pigmentation, as well as its pathogen resistance. The phenolic content of most fruits declines from early growth stages till attainment of physiological maturity. During maturation and development, the phenolic compounds undergo a sequence of intricate metabolic processes, resulting in compositional changes of the plant and plant derived foods. Flavonoids are present in various horticultural commodities in the form of conjugates i.e. glycosylated or esterified forms. Characteristic flavonoid compounds present in pummelos: Anthocyanin & Lycopene Total flavoinoid content of the pummelo juice varied from 11.47 to 57.80 mg QE/100ml.
Fig: Changes in total antioxidant capacity (TAC) (A) & DPPH radical scavenging activity (B) in juice sacs of Hongroumiyou (HR), Bairoumiyou (BR) and Huangroumiyou (HuR) pummelo during postharvest storage. Total antioxidant capacity (TAC) & DPPH radical scavenging activity
Fig. The possible mechanism of changes in metabolisms of antioxidant and cell wall in juice sacs of three pummelo cultivars during postharvest storage
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Biochemical changes during post harvest storage of pummelo

  • 1. Biochemical changes during post harvest storage of pummelo Submitted to: Dr Monica Sachdeva Taggar Assistant Biochemist Submitted by: Mandeep Kaur
  • 2. Introduction to Pummelo Pummelo (Citrus grandis) is one of the largest citrus fruits. The fruit flesh is normally consumed rather than processing it into a juice. It is renowned for its good flavor and juicy texture. In addition, it’s flesh contains important nutrients including vitamin C, potassium, pectin, natural folic acid and chromium. Local NRCC Pummelo - 2 PTF - 4
  • 3. Physio-biochemical changes in harvested pummelo fruit Respiration rate varies with the state of maturity and ripening in many fruits. The rate increasing to a maximum just prior to full ripening the phase called the climacteric. Citrus spp. (orange, acid lime, lemon, grapefruit and pummelo) are non-climacteric fruits. The respiration rate does not accelerate after harvesting. Non-climacteric fruits are best when ripened before harvesting.
  • 4. Non – Climacteric Fruit Ripening Fig: Growth, respiration and ethylene production in non-climacteric fruits (Wills, 2007)
  • 5. Ke D, 1993; Yang and Hoffman1984 Ethylene Biosynthesis & Ripening
  • 7. Synthesis of carotenoids & anthocyanin The colour change from green to orange or red in many fruits is due to the loss in chlorophyll and synthesis of carotenoids. Carotenes (hydrocarbons) Xanthophylls (their oxidized derivatives : hydroxy, oxy and epoxy compounds).
  • 8. Increase in activity of enzymes Softening of fruits during ripening is due to degradation of pectin by pectinase like pectinase, polymethyl galacturonases, polygalacturonases, pectin esterase, pectin lyase.
  • 9. Starch hydrolysis As the fruit maturity progresses, the starch reserves get hydrolysed into sugars (glucose, fructose or sucrose). Further the complex sugars viz. sucrose are broken down into simple sugars viz. glucose and fructose with the catalytic action of enzyme invertase.
  • 10. Flavour/aroma compounds The flavour consists of basically three components viz. aroma, taste and mouth feel. The major flavouring compounds identified are esters, alcohols, aldehydes, acids and ketones. Product Flavour Grape fruit Nootakatone Lemon Citral Citral
  • 11. Volatile Compounds & Aroma Profiles Pink and white pummelo fruit contained similar volatiles, which mainly consisted of limonene, cis-β-ocimene, α-terpinene, linalool, methyl anthranilate, and indole. Volatiles originate from proteins, carbohydrates, lipids, and vitamins. Their primary difference was in the concentration ratio between limonene and linalool. Major volatiles in pummelo peels were terpene hydrocarbons. Pink pummelo peel contained higher levels of aldehydes (e.g. octanal, decanal and citral). Whereas some trace-level important compounds (e.g. β-sinensal, α- sinensal and nootkatone) were found only in white pomelo peel.
  • 12. Ascorbic acid/ vitamin C L-ascorbic acid (Vitamin C) is the naturally occurring ascorbic acid in fruits. A gradual rise in ascorbic acid content with fruit growth has been observed and the levels decline with the advancement of maturity and onset of fruit ripening and postharvest handling. It is found to be low at the time of harvest. The upsurge in ascorbic acid content during ripening of certain fruits could be due to increased lipid peroxidation, since fruit ripening is considered as an oxidative phenomenon necessitating the turnover of active oxygen species. The decrease in vitamin C during the later stages of ripening might be due to its oxidation to dehydroascorbic acid. The ascorbic acid content of pummelo fruits ranged from 37.70 to 84.49 mg/100ml juice.
  • 13. Fig. Changes in total phenols (TP) (A) and total ascorbic acid (TAA) (B) in juice sacs of HR, BR and HuR during postharvest storage.
  • 14. Phenols and flavonoids During ripening, there is a gradual change in certain secondary metabolites with the commencement of phenolic pathways. The newly synthesized phenolic compounds play a crucial role in the fruit pigmentation, as well as its pathogen resistance. The phenolic content of most fruits declines from early growth stages till attainment of physiological maturity. During maturation and development, the phenolic compounds undergo a sequence of intricate metabolic processes, resulting in compositional changes of the plant and plant derived foods. Flavonoids are present in various horticultural commodities in the form of conjugates i.e. glycosylated or esterified forms. Characteristic flavonoid compounds present in pummelos: Anthocyanin & Lycopene Total flavoinoid content of the pummelo juice varied from 11.47 to 57.80 mg QE/100ml.
  • 15. Fig: Changes in total antioxidant capacity (TAC) (A) & DPPH radical scavenging activity (B) in juice sacs of Hongroumiyou (HR), Bairoumiyou (BR) and Huangroumiyou (HuR) pummelo during postharvest storage. Total antioxidant capacity (TAC) & DPPH radical scavenging activity
  • 16. Fig. The possible mechanism of changes in metabolisms of antioxidant and cell wall in juice sacs of three pummelo cultivars during postharvest storage