Phenolic content, total

ANCos B DE, GONZALES E M and CANO M p (2000) Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit , J Agric Food Chem, 48 (10) 4565-70. 

The total phenolic content in XRPP was 1.10%. The major components were found to be p-hydroxybenzoic acid (0.44%), vanillin (0.19%), syringic acid (0.13%), and syringaldehyde (0.13%). The contents of p-hydroybenzaldehyde, vanillic acid and ferulic acid were 0.032, 0.015 and 0.020%, respectively. Gallic acid, protocatechuic acid and cinnamic acid were detected in trace amounts. 

Figure 6. Time course of effects of 10 ug chlorsulfuron per seedling on total phenolic content of sunflower hypocotyls expressed as -coumaric acid equivalents. Reproduced with permission from Ref. 75. Copyright 1983, J. Plant Growth Regul.

Kaur C and Kapoor HC. 2002. Anti-oxidant activity and total phenolic content of some Asian vegetables. Int J Food Sci Technol 37(2) 153-161. 

Zhou K and Yu L. 2006. Total phenolic contents and antioxidant properties of commonly consumed vegetables grown in Colorado. LWT Food Sci Technol 39(10) 1155—1162. 

It has been observed that treatment with natural antimicrobial volatiles also affected the antioxidant capacity of fruits (Ayala-Zavala and others 2005). ORAC values of control strawberries changed during storage at 7.5°C (Fig. 11.3, III). However, significant increases in antioxidant capacity values were observed in strawberries treated with methyl jasmonate, methyl jasmonate-ethanol, and ethanol. One explanation for this difference could be associated with differences on total phenol content (Ayala-Zavala and others 2005). 

Treatment of strawberry with methyl jasmonate resulted in a significant increase in total phenol content. However, even though antioxidant activity was the highest in those berries treated with methyl jasmonate, the combination methyl jasmonate-ethanol was the most effective in extending the shelf life. It appears that methyl jasmonate and ethanol treatments had an additive effect in maintaining quality of strawberries but not in retaining high antioxidant activity. 

A similar effect was observed in other fruits and vegetables, where UV-C treated strawberries showed a higher increment of phenols and PAL activity 12 hours after treatment than unirradiated (control)(Pan and others 2004), which could be the reason for the increment in total phenol constituents (Lancaster and others 2000). UV-C and UV-B caused a two- and threefold increase in content of resveratrol (a grape phenol constituent). Thus, mature Napoleon grapes that had been irradiated with UV-C light can provide up to 3 mg of resveratrol per serving (Cantos and others 2001). Therefore, UV-C treatments clearly cause a benefit effect, increasing total phenol content, which can be mainly attributed to the increment of PAL activity. 

Ontario-grown American ginseng extracts were shown to have low total phenolic content in comparison to some previously tested extracts. Ontario ginseng samples ranged from 0.67 to 6.98 p,g quercetin equivalents/mg extract whereas values were in the order of 60-269 p,g quercetin equivalents/mg extract for plants known to be rich in phenolic compounds (such as quercetin, catechin, and other flavonoids) [21],... 

Rousi, M. and Haggman, J. (1984). Relationship between the total phenol content of Scots pine and browsing by the Arctic hare. Silvae Genetica 33,95-97. 

Doka, O. Bicanic, D. D. Dicko, M. H. Slingerland, M. A. Photoacoustic Approach to Direct Determination of the Total Phenolic Content in Red Sorghum Flours. /. Agric. Food Chem. 2004, 52, 2133-2136. 

A similar study by Verrelli and coworkers, based on PCA of potentio-metric data, allowed the differentiation of Verdicchio wines according to the winemaker and the vintage. Furthermore, MLR and PLS models, validated by means of cross-validation, permitted the quantification of a number of oenological parameters, such as SO2, L-malic acid, and the total phenols content (Paolesse et al., 2008 Verrelli et ah, 2007). 

TABLE 5.6 Total phenolic content and antioxidant activity of morama bean seed coat and cotyledon... 

Table 5.6 shows the total phenolic content (determined using the Folin-Ciocalteu assay) and antioxidant activity (ABTS radical scavenging capacity) of extracts from morama bean seed coat and cotyledon prepared with acidified mefhanol. If is clear fhaf morama bean seed coat and cotyledon have appreciable levels of fofal phenolics and antioxidant activity. These phenolics are concentrated in the seed coat. It has been reported that the morama bean cotyledon contains high levels of the amino acid tyrosine (Maruatona et ah, 2010) which is phenolic in nature and can therefore confribufe fo fhe fofal phenolic content of the cotyledon as determined with the Folin-Ciocalteu assay. 

Table 6.5 shows the distribution of the three phenolies in the peel and flesh ofthe Korean Superior potato variety available in four sizes large, medium, small, and very small. The data indicate that the size of the potato does not seem to influence the total phenolic content, except that the ratio of peel to flesh for the very small potatoes (7.95) is about one half the corresponding ratios of the other three potatoes. These results indicate that the distribution of phenolic compounds between peel and flesh varies widely among different potato varieties. They also suggest that... 

Figure 14.5 Total phenolic content of multiple vegetables is shown. Russet Norkotah and an advanced breeding line labeled high potato are the two potato types used in this comparison.

Methods of analysis are needed to determine total phenolic content and the relative content of phenolic fractions by means of their different characteristics. Many analytical methods used for phenols have been empirical and not easily reproduced or rationalized (I). Procedures that are based on sound chemical principles and that are sufficiently verified deserve wider application. We are concerned here with recent work on such analyses for phenols in wines. Application cf these results may help solve a major problem in phenol research—the many different, too empirical, unrelatable values (ml KMn04, vanillin-to-leucoantho-cyanin ratio, etc.) obtained in different ways by different researchers. Uniform use of verified methods and uniform standards and methods of expressing results will aid in developing an understanding in this field. 

Singleton and Esau (I) reviewed the methods for phenol analysis of wine. They pointed out that study would be greatly advanced if one could determine the total content of phenolic substances and express it in such a way that analysis of subclasses of phenols could be related to the original total and a balance sheet could be obtained. One could then say, for example, this wine has a total phenolic content of 1200 mg/liter calculated as gallic acid, and of that total, cinnamic acid derivatives account for 200 mg/liter, anthocyanins for 300 mg/liter, other small flavonoids for 200 mg/liter, and condensed tannins complete the total with 500 mg/liter of gallic acid equivalent. To accomplish this, the total phenol analysis not only must meet ordinary criteria of reproducibility and precision, but it also must be based on chemical relationships such that fractions determined separately can be converted to units of the total. Of course when clearcut fractionation can be accomplished by... 

Phenolic substances can also be quantified by measuring absorbance at 280 nm. The applicability of this method is far more limited, however, because absorbance properties of different phenolics vary and cannot be related to a specific standard. Because of this, and because of the extreme ease of the method, spectral analysis is well suited for using total phenolic content for process monitoring. 

Total phenolic content the Folin-Ciocalteu reagent... 

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