Phenolic acids onion

NUUTILA A M, KAMMioviRTA K and OKSMAN-CALDENTEY K-M (2002) Comparison of methods for the hydrolysis of flavonoids and phenolic acids from onion and spinach for HPLC-analysis, Food Chem, 76, 519-25. 

More nsnal vegetables were stndied by Nnntila et al. [358] who characterized onions and spinach for the phenolic composition, with and without previous hydrolysis. The authors performed the simultaneous determination of phenolic acids, flavonols, flavones glycosides, and cathechins. Fignre 19.9 reprodnces the separation obtained for the standard mixture in this study. 

FIGURE 19.9 HPLC chromatogram of standards of phenolic acids, flavonols, flavones, and glycosides isolated in onions and spinach. (From Nnntila, A.M. et al., Food Chem., 76, 519, 2002. Copyright 2002. With permission from Elsevier.)... 

Soltoft, M. Nielsen, J. Laursen, K.H. Husted, S. Halekoh, U. Knuthsen, P. 2010. Effects of organic and conventional growth systems on the content of flavonoids in onions and phenolic acids in carrots and potatoes. J. Agric. Food Chem. 58 10323-10329. 

One-stage resin. See Phenolic resin Oniachlor. See Trichloroisocyanuric acid Onion (Allium cepa) extract CAS 8054-39-5 EINECS/ELINCS 232-498-2 Synonyms Allium cepa Allium cepa extract Onion extract... 

Bocco, A. CuveUer, M.E. Richard, H. Berset, C. Antioxidant activity and phenolic composition of citrus peel and seed extracts. J. Agric. Food Chem. 1998,46,2123-2129. Nuutila, A.A. Kammiovirta, K. Oksman-Caldentey, K.M. Comparison of methods for the hydrolysis of flavonoids and phenolic acids from onion and spinach for HPLC analysis. Food Chem. 2002, 76, 519 525. 

Elavanols Elavonols Cinnamic acid Phenolic acids Stilbenoid 15 Carrot, tomato, broccoli, onion, garlic, pepper, beetroot QuECHERS + clean up Acetonitrile ethylacetate (50 50) 15 min + clean up 78-99 [51]... 

Although tomato was the matrix most studied with this technique, other matrices such as pepper, eggplant, apple, pear, beans, mango, orange, citrus fruit, onion, garlic, potato, chillies, and strawberries were also studied by UAE. The extracted phenolic compounds included phenolic acids, isoflavones, flavonols, flavonones, fla-vones, flavonones, cinnamic acids, dihydrochalcones, chalcones, flavanols, and pro-cyanidins (Table 16.3). 

Chromosome aberrations CHO cells Onion root tips Simple phenols phenolic acids cinnamic acids Chlorogenic acid Several phenolics Stich et al. (1981a) Stich et al. (1981b) Levan and Tjio (1948)... 

Phenohc acids are nonflavonoid polyphenolic compounds that mainly exist in two forms based on C1-C6 and C3-C6 backbones, benzoic and cinnamic acid derivatives, coimnonly known as hydroxycinnam-ic and hydroxybenzoic acids. Hydroxybenzoic acids (Figure 3.9) are found in a few plants consumed by humans, such as berries and onions [54], While vegetables and fhiits contain many free phenolic acids, in seeds and grains, particularly in the bran or hull, phenolic acids are... 

Other constituents present in onion include phenolic acids (caffeic, sinapic, p-coumaric, protocatechuic acids, etc.), flavonoids (e.g., quercetin, isorhamnetin, taxifolin, and their glucosides), anthocyanins (e.g., cyanidin, carboxypyranocyanidin, and peonidin glycosides), sterols (cholesterol, stigmasterol, P-sitosterol, etc.), saponins (e.g., trope-osdies and ascalonicosides), sugars,... 

The Fourier Trairsform Infrared (FTIR) spectrum obtained from non-adapted tomato cell walls is very similar to that from the onion parenchyma cell wall (both contain cellulose, xyloglucan and pectin) although there is more protein in the tomato walls (amide stretches at 1550 and 1650 cm-i) (Fig 4). In DCB-adapted tomato cell walls, the spectrum more closely resembles that of either purified pectins or of a commercial polygalacturonic acid sample from Sigma with peaks in common at 1140, 1095, 1070, 1015 and 950 cm-t in the carbohydrate region of the spectrum as well as the free acid stretches at 1600 and 1414 cm-i and an ester peak at 1725 cm-k An ester band at 1740 cm-i is evident in both onion parenchyma and non-adapted tomato cell wall samples. It is possible that this shift in the ester peak simply reflects the different local molecular environment of this bond, but it is also possible that a different ester is made in the DCB-adapted cell walls, as phenolic esters absorb around 1720 cm-i whilst carboxylic esters absorb at 1740 cm-k The... 

Fig. (10). HPLC chromatogram of red onion anthocyanins and other phenols (1) quercetin 3,4 -diglucoside, (2) quercetin 4 -glucoside, (3) isorhamnetin 4 -glucoside, (4) cyanidin 3-glucoside, (5) cyanidin 3-arabinoside, (6) cyanidin 3-malonylglucoside, and (7) cyanidin 3-malonylarabinoside. HPLC conditions RP Cig column (12 x 0.4 cm particle size 5 im). Mobile phase acidified water (5% formic acid) (A) and methanol (B). Gradient 0 min- 15% B, 15 min- 35% B, 25 min- 40% B. Flow rate 1 mL/min.

Fig. 10 shows HPLC chromatograms of red onion phenolics. Four anthocyanins are visible in the 520 nm chromatogram and three principal flavonoids can be clearly observed in the 260 nm chromatogram. Hydroxycinnamic acid or benzoic acid derivatives cannot be observed in any significant quantity in the chromatograms. 

Cheese flavor. C. f. is formed from milk fat, milk protein, lactose during the maturation of cheese mainly through enzymatic and microbial processes. Quantitative and, sometimes, qualitative differences are responsible for the diversity of cheese flavors. Typical aroma substances are the free C4-C,2 fatty acids, C7, C and C, 2-alkanones (also in Roquefort cheese), the butter aroma substances acetoin, 2,3-butanedione, and 5- alkanolides, (-)-(R)-l-octen-3-ol (fungus note in Camembert), 4-alkanolides and alkylpyrazines with nut-like nuances, indole, skatole, and phenols with stable-like odors, as well as numerous sulfur compounds such as methional, methyl mercaptan (moldy, coal-like), dimethyl sulfide and dialkyl polysulfides with, in part, onion- and garlic-like nuances. Furaneol" and homofuraneol (see hydroxyfura-nones) are responsible for the sweetish odor of Em-mental cheese. 

Not only do people consider Allium vegetables important because of their characteristic flavor that contributes to the savoriness of various dishes in world cuisine, they are also aware of the nutritional potential of these vegetables since they are rich in nutrients such as high levels of phosphor, potassium, zinc, vitamins A, C and D, foUc acid, calcium and selenium etc. is also considered by people (Peter 2000 Rahman 2003). They are also rich sources of phenolic compounds (Vinson et al. 1998). Table 4.1 shows the approximate composition of fresh garlic and onion bnlbs. 

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