Influence of Developmental Stage on Activities of Polyphenol Oxidase, Internal Characteristics and Colour of Lettuce cv. Grand Rapids

Chutichudet, Benjawan; Chutichudet, Prasit; Kaewsit, S

doi:10.3923/ajft.2011.215.225

Cited by 20 publications

(18 citation statements)

References 39 publications

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“…Rawalpindi city contained vegetables of pH 4.75 (FMS105abc, tomato, Khannapul) to 6.23 (FMS217abc, lettuce, Rajabazar). This result is similar to the findings of Dobricevic et al (2005) [10] and Chutichudet et al (2011) [11]. pH values of cabbage and lettuce were found to be close to one another while that of cucumber and tomato varied differently from other vegetables tested.…”

Section: Sample Analysis: Ph Studiessupporting

confidence: 91%

Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets

Alam¹,

Khalil²,

Ayub³

et al. 2013

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Nutritional value of vegetables and high prices of meat and meat originated food compel common people to consume plant originated food particularly salad vegetables. Microbial population of vegetable surfaces contains a large number of pathogenic bacteria including members of Enterobactereace like Escherichia coli (E. coli). A survey was conducted in three major markets of Rawalpindi, Pakistan. Tomato, lettuce, cabbage and cucumber samples were collected from three shops of each market. Each vegetable was analysed as unwashed and washed for total coliforms, faecal coliforms and E. coli by FAO (Food Quality Manual). About two hundred and fifty E. coli isolates were preserved, serotyped for presence of O157 serotype. Total coliforms, faecal coliforms and E. coli count exceeded the permissible limits in most samples. The highest Total coliforms were associated with cabbage (3.78 log 10 cfu/g). Cucumber was the least contaminated by Total coliforms (2.15 log 10 cfu/g). E. coli was detected in tomato, lettuce, cucumber and cabbage. Washed samples showed reduced bacterial population. Seventy six isolates of E. coli were biochemically characterized and serotyped for O157 antigen. A majority of strains could not be identified by serotyping. These findings conclude with high potentially pathogenic microbial load on salad vegetables and urge for preventive action on priority basis.

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Section: Sample Analysis: Ph Studiessupporting

confidence: 91%

Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets

Alam¹,

Khalil²,

Ayub³

et al. 2013

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“…This result also corroborated with other reports. [55] Compared with results reported by Dudai et al [23] about 1000 times higher concentration of TPC in Ethiopian khat have been noticed. This could be due to variation in various environmental factors listed above and some possible problems mentioned under the introduction section.…”

Section: Effect Of Variable Parameters On Extraction Of Total Phenolimentioning

confidence: 61%

Selected Secondary Metabolites and Antioxidant Activity of Khat (Catha edulisForsk) Chewing Leaves Extract

Atlabachew

Chandravanshi

Redi

2013

International Journal of Food Properties

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Total phenolic, flavonoid, and tannin contents of 21 Ethiopian khat (Catha edulis Forsk) leaves and their related antioxidant activities were determined in the extracts of the young leaves, matured leaves, and tips of tender stem near the young shoots. A simplified, rapid, and robust method was also optimized for the analysis of total tannins using ovalbumin as a precipitating agent and Folin Denis reagent as the quantification technique. Among the solvents tested, aqueous mixtures of 70 and 80% acetone and 80% methanol provided higher phenolic compounds extraction efficiency than the corresponding pure solvents and other binary mixtures. Results of the analysis revealed that total phenols ranged from 129 to 274 mg tannic acid equivalent/g of dried young leaves and 89.3 to 175 mg tannic acid equivalent/g of dried tender stem tips. Total tannin content ranged between 70.2−153 mg tannic acid equivalent/g and 49.4−103 mg tannic acid equivalent/g of the dried young leaves and tips of tender stems, respectively. Similarly, total flavonoids concentration as catechin equivalent varied between 26 to 75 and 26 to 56 mg catechin equivalent/g of dried young leaves and tips of tender stems, respectively. Khat cultivars were found to pose a substantial antioxidative activity (as ascorbic acid equivalent) ranging between 173−290 and 118−211 mg ascorbic acid equivalent/g of dried young leaves and tips of tender stems near the young shoot, respectively. Matured leaves of khat accumulated a significantly lower concentration of secondary metabolites compared to the corresponding young leaves. This study reveals that khat leaves and tender stems accumulated a substantial amount of secondary metabolites, particularly tannins.

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“…Lettuce contains multiple health-beneficial components, including polyphenols, ascorbic acid, carotenoids, and tocopherols. These compounds have protective effects against cancers, cardiovascular disorders, and other chronic diseases [4] .…”

Section: Introductionmentioning

confidence: 99%

The effects of different night-time temperatures and cultivation durations on the polyphenolic contents of lettuce: Application of principal component analysis

Jeong

Kim

Lee

et al. 2015

Journal of Advanced Research

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The present study was conducted to characterize the polyphenolic contents of lettuce leaves grown under different night-time temperatures (4, 12, and 20 °C) and cultivation durations (5, 15, and 20 days) using high performance liquid chromatography-tandem mass spectrometry (LC/MS/MS). The assay method was validated based on specificity, linearity, accuracy, precision, and the performance limit. The total polyphenolic contents were highest (2462.6 mg/kg) after transplantation at a night temperature of 20 °C on day 20 and lowest (1132.7 mg/kg) at the same temperature on day 5. Quantification and principal component analysis showed that the relative contents of quercetin and kaempferol were markedly higher during the early stage of cultivation (day 5) than those of day 15 and 20, and that night-time temperatures of 12 and 20 °C on day 20 were favorable for producing polyphenol-rich lettuce containing caffeic acid. In conclusion, a synergistic effect between high night-time temperatures (12 and 20 °C) and cultivation duration (20 days) produced lettuce rich in polyphenols compared to that at low temperature (4 °C).

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Influence of Developmental Stage on Activities of Polyphenol Oxidase, Internal Characteristics and Colour of Lettuce cv. Grand Rapids

Cited by 20 publications

References 39 publications

Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets

Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets

Selected Secondary Metabolites and Antioxidant Activity of Khat (Catha edulisForsk) Chewing Leaves Extract

The effects of different night-time temperatures and cultivation durations on the polyphenolic contents of lettuce: Application of principal component analysis

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Influence of Developmental Stage on Activities of Polyphenol Oxidase, Internal Characteristics and Colour of Lettuce cv. Grand Rapids

Cited by 20 publications

References 39 publications

Prevelance of total coliforms, faecal coliforms and &lt;i&gt;E. coli&lt;/i&gt; in Rawalpindi vegetable markets

Prevelance of total coliforms, faecal coliforms and &lt;i&gt;E. coli&lt;/i&gt; in Rawalpindi vegetable markets

Selected Secondary Metabolites and Antioxidant Activity of Khat (Catha edulisForsk) Chewing Leaves Extract

The effects of different night-time temperatures and cultivation durations on the polyphenolic contents of lettuce: Application of principal component analysis

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Product

Resources

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Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets

Prevelance of total coliforms, faecal coliforms and <i>E. coli</i> in Rawalpindi vegetable markets