Effect of drying methods on physico-chemical and antioxidant properties of date fibre concentrates
Effects of different drying methods (freeze-; oven- and sun-drying) on physico-chemical properties of date fibre concentrates (DFC) from three potential Tunisian cultivars were investigated. DFC had high contents of dietary fibre (71.01Â93.46% dry matter); with high proportions of insoluble dietary fibre. Freeze dried DFC had the highest values of swelling; water holding and oil holding capacities. This drying method gave also the lightest DFC colour. Kentichi fibre produced by freeze-drying had the highest viscosity and the lowest bulkier particles. The present work assessed polyphenol content and antioxidant activity of DFC using 1;1-diphenyl-2-picrylhydrazyl (DPPH) method. The highest polyphenol content was found for freeze dried DFC; contrary to radical scavenging activity which was not affected by drying methods. Results suggest that freeze dried DFC had the highest potential to be used as a functional ingredient in food products.
Walnut (Juglans regia L.): genetic resources; chemistry; by-products
Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry; productivity; physical and chemical nut traits. Some of them have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg(-1) in some commercial varieties); which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols; phospholipids; sphingolipids; sterols; hydrocarbons and volatile compounds. Phenolic compounds; present at high levels in the seed coat but poorly extracted with the oil; have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine; glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics.
The influence of roasting; pasteurization; and storage on the polyphenol content and antioxidant capacity of California almond skins
Polyphenols and antioxidant activity of skins from California almonds subjected to roasting; pasteurization; and storage were determined by LC-MS quantification; total phenols (TP); and ferric reducing antioxidant power (FRAP). Pasteurization did not significantly change TP; FRAP; or flavonoids and phenolic acids (FP). Roasted almonds had 26% less TP and 34% less FRAP than raw; but equivalent FP (n = 12). Storing almonds at 4 and 23°C for 15 mo resulted in gradual increases in FP; up to 177 and 200%; respectively (n = 13). At 4°C and 15 mo; polyphenols increased 18-fold for p-hydroxybenzoic acid; while others were 45 to 200% higher compared to baseline values. Isorhamnetin-3-O-rutinoside accounted for 48% of the increase in FP. After 15 mo; FRAP and TP increased to 200 and 190% of initial values. Accelerated aging of whole almonds increased FP content by 10% after 3 days; but TP and FRAP values were not significantly different from baseline to day 10. Thus; in almond skins; roasting decreases TP and FRAP but not FP; while storage for up to 15 mo doubles FP.
Phenolic compounds and antioxidant activity of Brazil nut (Bertholletia excelsa)
Brazil nuts were shelled and separated as kernel and brown skin; whole nuts were also used. Soluble phenolics from each portion as well as the whole nut were extracted using 70% acetone under reflux conditions. Insoluble-bound phenolics were subsequently extracted into diethyl etherÂethyl acetate mixture (1:1; v/v) after alkaline hydrolysis. Both soluble and insoluble-bound phenolic extracts were separately examined for their total phenolics content; antioxidant activities were evaluated by trolox equivalent antioxidant capacity (TEAC); 1;1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activities using electron paramagnetic resonance (EPR); reducing power; and oxygen radical scavenging capacity (ORAC). Soluble phenolics in brown skin was 1236.07 as compared to 406.83 in kernel and 519.11 mg/100 g in whole nut. Bound phenolics content of brown skin was also 86- and 19-folds higher than kernel and whole nut; respectively. Similarly extracts from the brown skin exhibited the highest antioxidant activity. Free- and bound phenolics were identified and quantified; these included nine phenolic acids and flavonoids and their derivatives (gallic acid; gallocatechin. protocatechuic acid; catechin; vanillic acid; taxifolin; myricetin; ellagic acid; and quercetin). However; some phenolics were present only in the bound form. Furthermore; the phenolics were dominant in the brown skin.
Roast effects on the hydrophilic and lipophilic antioxidant capacities of peanut flours; blanched peanut seed and peanut skins
Hydrophilic and lipophilic oxygen radical antioxidant capacity (H&L-ORAC) of peanut flours; blanched peanut seed; and peanut skins were characterized across a range of roast intensities. H-ORAC ranged from 5910 to 7990; 3040 to 3700 and 152;290 to 209;710 µmoles Trolox/100 g for the flours; seed; and skins; respectively. H-ORAC increased linearly with darker seed color after roasting at 166 °C from 0 to 77 min; whereas skin H-ORAC peaked after roasting for 7 min. Linear correlations with H-ORAC and total phenolic content were observed. Additionally; completely defatted peanut seed were solubilised (5% w/w) in water and H-ORAC measured. For these samples; H-ORAC decreased with roast intensity which correlated with soluble protein. L-ORAC ranged from 620 to 1120; 150 to 730 and 2150 to 6320 µmoles Trolox/100 g for peanut flours; seed; and skins; respectively. L-ORAC increased linearly with both darker seed color and skin color across the 77 min range. L-ORACs of roasted peanuts and ingredients are discussed in terms of tocopherol contents and Maillard reaction products.
Process development of a chocolate-flavored peanut-soy beverage
A new beverage product was developed utilizing two protein-rich oilseed sources; namely peanut and soy. Medium-roasted peanut flour and chocolate flavor were incorporated to offer pleasant flavor profile. The peanutÂsoy combination would also improve essential amino acid profile especially that of lysine; compared with an all-peanut product. A pilot-plant scale beverage-processing protocol involved filtration; homogenization and pasteurization as the major operating steps. Beverage formulation employed a three-component constrained mixture design. The low- and high-bound constraints were determined for peanut (30.6Â58.7%); soy (28.3Â43.5%) and chocolate syrup (13.0Â25.9%) based on lysine content; viscosity and visual stability index values of 51-mg g-1 protein; 36.9 mPa s and 1.00; respectively. The beverage formulation and processing protocol thus developed were the basis for further study on consumer acceptability of the new chocolate-flavored peanutÂsoy beverage.
Antiradical activity of extracts of almond and its by-products
Antioxidant activities of ethanolic extracts of whole almond seed, brown skin, and green shell cover were evaluated using different free radical trapping assays. Trolox equivalent antioxidant capacity assay revealed that the total antioxidant capacities of brown skin and green shell cover extracts were 13 and 10 times greater than that of the whole seed extract at the same extract concentration. The free radical-scavenging activity of extracts of brown skin and green shell cover also exceeded that of the whole seed. The scavenging activity of superoxide radical by different almond extracts ranged from 76 to 97% at 100 ppm and 85 to 99% at 200 ppm. The corresponding reduction of hydrogen peroxide concentration was 59–66% (100 ppm) and 86–91% (200 ppm). The hydroxyl radical-scavenging capacities at 100 and 200 ppm were 16 and 42% for whole seed, 57 and 100% for brown skin, and 40 and 56% for green shell extracts, respectively. A 100% scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was observed for brown skin and green shell extracts at 100 and 200 ppm concentrations, respectively, and whole seed extracts scavenged 21 (at 100 ppm) and 73% (at 200 ppm) of the DPPH radical.
Scalping of flavors in packaged foods.
Food packaging, although an integral part of the food chain, has a major drawback in that, often, the packaging material interacts with the flavor constituents of the food, causing either a selective or an extensive loss of desirable food flavors or absorption of undesirable off-flavors from the packaging material, thereby resulting in an eventual loss of quality of the packaged food item. The process is called “scalping” and is of great concern to the food industry, which is always looking out for new avenues in “packaging solutions” for its final product quality needs. The review highlights the various attributes of the scalping process, explores approaches to the reduction of the manifested undesirable effects, and covers other relevant aspects.