Berry extraction method

Due to the different methods used for evaluating antioxidant capacity of flavonoid from grapes and berries, direct comparisons between various species and products often cannot be made. However, a wide range of berry extracts, wines and juices... 

In a study of 92 Finnish edible and nonedible plant materials, a total of 15 berry samples were screened for antioxidant activity (Kahkonen et al., 1999). The activity was compared with the total phenolic content of the samples. Inhibition of methyl linoleate oxidation was used as a measure of antioxidant activity of berry acetone extracts and total phenolics determined by the Folin-Ciocalteau method as GAE/g dry matter of extracts. Berry extracts were high in antioxidant activity among the... 

Lee et al. (2005) proposed a method for analysis of flavonols in grape by performing berry extraction with acidified methanol (0.01% of 12 N HC1). After filtration, the solvent is removed under vacuum and the residue is dissolved in a 0.1 M citric acid buffer with pH 3.5. First, polyphenols are fractionated on a reverse-phase Ci8 cartridge (e.g., Sep-Pak 5g), then on a Sephadex LH-20 3-g cartridge (a cross-linked dextran-based stationary phase used for gel permeation, normal-phase partition, and adsorption chromatography). Four fractions finally are recovered by ethyl acetate and methanol, as shown in the f >w diagram Fig. 6.5. 

Tannins and anthocyanins are key wine component groups. Since the skins and seeds contain the most of the phenolics, red wine is a whole berry extract. In addition, because of the significant sensory effects of these substances on bitterness and astringency, they are controlled by winemakers. The methods of control involve the manipulation of extraction as well as fining with protein to precipitate and remove tannin from finished wine technological enological process as nano- or ultrafiltration is now seeing some use. While many studies have... 

The DPPH assay (5) was used to evaluate the free-radical-scavenging capacity of extracts prepared by the methods outlined above, whole berry extract and commercial cranberry juice cocktail (Ocean Spray Inc.). Activity was compared to that of a standard antioxidant (Vitamin E, Aldrich Chemical Co.) measured using the same methods. Varying concentrations of cranberry extracts were mixed with a 60 pM solution of DPPH in methanol. Quenching of the violet DPPH radical was observed as a decrease in absorbance at 515 nm over one hour. EC50 values are measured as the sample concentration required to decrease DPPH absorption by 50%. Results are shown in Table I. The DPPH assay was also used to evaluate the extracts of peel, solids and juice EC50 values are reported in Table V. 

Table I shows the results of a DPPH radical-scavenging assay on each of the whole-cranberry extracts prepared by Mediods 1 and 2. For whole cranberries, the highest antioxidant activity was observed in ethyl acetate extracts prepared by both methods, with an IC50 value of 0.033 mg/mL for the ethyl acetate extract prepared by Method 2. The ethyl acetate fraction was about twice as effective at radical scavenging as the whole-berry extract (IC50 = 0.078 mg/mL). Kinetics of these reactions were slow compared to the standard. Vitamin E for all cranberry extracts, radical scavenging occurred over a period of approximately one hour as compared to several minutes for vitamin E.

Compounded gin is produced by a dding extracts of juniper berries and other botanicals to high proof neutral spirits. This gin is perceived to be a lower quahty than distiked gin and not much is produced by this method. 

Romero-Perez AI, Lamuela-Raventos RM, Andres-Lacueva C and Torre-Boronat MC. 2001. Method for the quantitative extraction of resveratrol and piceid isomers in grape berry skins. Effect of powdery mildew on the stilbene content. J Agric Food Chem 49(1) 210-215. 

Extensive reviews of analytical methods for anthocyanins (Francis, 1982 Jackman et al., 1987b Strack and Wray, 1994) and other flavonoids (Williams and Harbome, 1994) as well as phenolic acids (Herrmann, 1989) have been published. In these reviews, extraction procedures, methods for fractionation of groups of polyphenols and the identification and quantification of individual components are presented. Here, a brief presentation of more recently published methods for grape and berry polyphenolic analyses is given with respect to their relationship to antioxidant activity and health benefits. 

A satisfying method of sample preparation for GC/MS analysis of grape extract and used in several studies (Mateo et al., 1997 Chassagne et al., 2000 Flamini et al., 2001 2006), was proposed by Williams et al. (1982) and Di Stefano (1991). Skins of 100 berries are separated from the pulp and are extracted with 35 mL of methanol for 4h in the dark. Pulp and juice are reunited in a glass containing lOOmg of sodium metabisulfite. 

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