Raspberries phenolic

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. 

Pantelidis GE, Vasilakakis M, Manganaris GA and Diamantidis GR. 2007. Antioxidant capacity, phenol, an-thocyanin and ascorbic acid contents in raspberries, blackberries, red currants, gooseberries and Cornelian cherries. Food Chem 102(3) 777-783. 

Few of the phenol derivatives that have a keto substituent in their side-chain are of interest as fragrance or flavor substances. A number of phenols and phenyl ethers acetylated in the benzene ring have been identified as volatile components of foods. 4-Methoxyacetophenone is of some interest as a fragrance material. 4-Hydroxybenzylacetone, a higher mass phenol ketone, has a characteristic raspberry aroma. 

Raspberry ketone is prepared by alkali-catalyzed condensation of the alkali salt of 4-hydroxybenzaldehyde and acetone, followed by selective hydrogenation of the double bond in the resulting 4-hydroxybenzalacetone. Other syntheses start from phenol which is converted into 4-(4-hydroxyphenyl)-2-butanone with methyl vinyl ketone (e.g., in the presence of phosphoric acid) [179] or with 4-hydroxy-2-butanone in the presence of concentrated sulfuric acid [180]. 

Mullen W, McGinn J, Lean MEJ, Maclean MR, Gardner P, Duthie GG, Yokota T, Crozier A. 2002. Ellagitannins, flavonoids, and other phenolic compounds in red raspberries and their contribution to antioxidant capacity and vasorelaxation properties. J Agric Food Chem 50 6902-6909. 

When the parent phenol complex of [Os] 85 is combined with MVK and pyridine in acetonitrile, a Michael addition occurs to give the 4H-phenol complex 86 in 91 % yield (Scheme 11). This complex is remarkably stable and resists rearomatization even when allowed to stand in an acidic solution of acetonitrile for 24 h. However, addition of an amine base induces rearomatization to yield complex 87. This complex may be heated to afford the deme-talated substitution product 88 (raspberry ketone) in 71 % yield (based on 85) [29]. 

Wu, X. Pittman, H.E. Hager, T. Hager, A. 2009. Phenolic acids in black raspberry and in the gastrointestinal tract of pigs fed black raspberry. Mol. Nutr. Food Res. 53 S76-S84. 

Figure 3.2 HPLC chromatograms of phenolic acids in raspberry pomace before and after aeid hydrolysis.

Rommel, A. Wrolstad, R.E. 1993. Influence of acid and base hydrolysis on the phenolic composition of red raspberry juice. J. Agrie. Food Chem. 41 1237-1241. 

A variety of benzene-derivatives are found in many grape varieties, including vinyl phenols, benzyl alcohol, 2-phenyl ethanol and raspberry ketone. Vinyl phenols are characterised by spice and dove-like, 2-phenyl ethanol by rose and lilac, and raspberry ketone by a raspberry attribute (Francis and Newton 2005). It should be noted that, although a portion of 2-phenyl ethanol can derive from glycoside hydrolysis, a greater proportion of this compound is formed in the metabolism of the amino acid phenylalanine (Ugliano et al. 2006). 

Black raspberries are not included among the top twenty superfruits because they contain higher phenolic acid contents, are therefore sour if not bitter in taste, and are generally not enjoyed as much for fresh eating as the red species. Also, there is a limited supply of black raspberries in North America as this species has not been well crossbred to increase its resistance to plant diseases. Accordingly, farmers have not invested in black raspberries as a plant with higher disease risk and lower yield. 

Red raspberries contain dense contents of ellagic acid, ellagitannins, and several other polyphenols under active research for potential health benefits as anti-inflammatory factors. These phenolic compounds have importance in research on diseases that start first with inflammation, such as cancer, chronic arthritis, Alzheimer s disease, diabetes, and obesity. In research done at Cornell University, scientists studying four cul-tivars of red raspberry identified differences in polyphenol content that were directly related to the color intensity of the respective juices. The color of the juice correlated well to the anthocyanin contents of each raspberry cultivar. In the same studies, proliferation of human liver cancer cells—as part of a laboratory test of potential anticancer activity— was significantly suppressed by the raspberry polyphenols. 

Wang and Lin (2000) measured antioxidant activity (ORAC) and total phenolic and anthocyanin contents of thornless blackberry, strawberry and red and black raspberry fruits and found linear relationships between both ORAC and total phenolics and between ORAC and anthocyanins of ripe fruits. Spray-dried elderberry juice with high amounts of anthocyanin glucosides caused prolongation of the lag-phase for Cu-induced oxidation of human LDL, while the maximum oxidation rate remained unchanged (Abuja et al., 1998). For peroxyl-radical-driven LDL oxidation, however, both prolongation of lag time and reduction of maximum oxidation rate occurred. 

During storage of fresh strawberries, raspberries and highbush and lowbush blueberries at 0,10,20 and 30°C for up to 8 days, the antioxidant capacity was found to be stable or even to increase (Kalt et al., 1999a). The antioxidant capacity was strongly correlated with the content of total phenolics (r = 0.83) and anthocyanins... 

Traditionally raspberry ketone has been produced by reaction of phenol with methyl vinyl ketone in the presence of a Friedel-Crafts catalyst in an inert solvent at a temperature between — 5°C and +5°C and in the absence of an acid alkylation catalyst. UK patents 876684 and 876685 granted to Dragoco describe the process in detail. Some modifications and new developments have also been mentioned in the said patents [29]. 

Phenol route was the chosen one since p-hydroxy-benzal-dehyde so far was expensive. The only source of obtaining p-hydroxy benzaldehyde was as a by-product during production of salicylaldehyde. Since p-hydroxybenzaldehyde now can be easily made from p-cresol by direct oxidation, the product will be relatively cheaper and should prove to be an ideal feedstock for making raspberry ketone. 

Similarly, raspberry ketone has so far been made from phenol (and methyl vinyl ketone). However, in view of easy availability of p-hydroxy benzaldehyde from p-cresol at a reasonable price, raspberry ketone can now be made by condensation of alkali catalysed p-hydroxy benzaldehyde and acetone followed by mild hydrogenation of the double bond. 

Facile Friedel-Craft s alkylation of phenol with 4-hydroxybutan-2-one over p and Y zeolites to produce raspberry ketone... 

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