Inhibitory effect of raspberries on starch digestive enzyme and their antioxidant properties and phenolic composition

Seven primocane fall-bearing raspberry (Rubus idaeus L.) cultivars, Nova (red), Dinkum (red), Heritage (red), Autumn Britten (red), Josephine, Anne (yellow), Fall Gold (yellow) were analysed for potential health promoting properties including their inhibitory effect on starch and fat digestive enzymes, antioxidant activities, and phenolic composition. The tested raspberry extracts showed no detectable inhibition of pancreatic α-amylase and lipase. However, all the extracts exhibited potent inhibition of α-glucosidase with IC₅₀ from 16.8 to 34.2 μg/mL. Four phenolic compounds, ellagic acid, cyanidin-diglucoside, pelargonidin-3-rutinoside, and catechin were identified as the active α-glucosidase inhibitors. The raspberry extracts also possessed significant antioxidant activities with oxygen radical absorbance capacities (ORAC) ranging from 136.7 to 205.2 μmol Trolox equivalents (TE)/g dry weight fruit and DPPH radical scavenging activities from 305 to 351 μmol TE/g. The total phenolic content of raspberry cultivars varied significantly from 40.9 to 98.5 mg of gallic acid equivalents/g dry weight. The anthocyanin content varied widely from 0.1 to 9.5 mg cyanidin 3-glucoside equivalents/g. Nine phenolic acids were quantified in raspberries and their total amounts varied from 157.3 to 713.5 μg/g. The enzyme inhibition and antioxidant properties of raspberry cultivars were not correlated with their total phenolic, anthocyanin, and phenolic acid content. Overall, ‘Dinkum’ and ‘Josephine’ raspberry varieties possess higher total phenolic content, ORAC, DPPH radical scavenging activity, and α-glucosidase inhibitory activity than other five cultivars.     

Effect of γ-radiation on green onion DNA integrity: Role of ascorbic acid and polyphenols against nucleic acid damage

The effect of γ-radiation on green onion DNA integrity, phenol content, oxygen radical absorbance capacity, employing pyrogallol red and fluorescein as probes, as well as ascorbic acid content has been evaluated. Measurements using thiazole orange-DNA fluorescence and agarose gel electrophoresis show that γ-radiation does not lead to an apparent DNA change in green onion. However, it was readily cleaved upon irradiation from the previously isolated nucleic acid. Furthermore, green onion exposure to γ-radiation produces slight increases in the polyphenol concentrations (163–188 μM Trolox eq.) and a decrease in the oxygen radical absorbance using fluorescein (from 245 to 200 Trolox eq.) Interestingly, a high ascorbic acid content (364 μM), which decreases by 40% after γ-ray exposure was measured by using pyrogallol-red-based oxygen radical absorbance capacity induction times from green onion aqueous extracts. Thus, our results suggest that ascorbic acid present in green onion plays a fundamental role in the plant antioxidant response toward γ-radiation exposure, while polyphenols remain largely unchanged, as revealed from oxygen radical absorbance capacity, employing pyrogallol red.     

Use of the Oxygen Radical Absorbance Capacity (ORAC) Assay to Predict the Capacity of Mango (<Emphasis Type="Italic">Mangifera indica</Emphasis> L.) By-Products to Inhibit Meat Protein Oxidation

The potential activity of mango by-products to inhibit the peroxyl radical-mediated oxidation of tryptophan residues (Trp) of myofibrillar proteins (MP) was studied. Extracts of seeds, peels and pulps were studied in terms of their antioxidant activity, assessed by the oxygen radical absorbance capacity (ORAC) assay employing fluorescein and pyrogallol red as probes (ORAC-FL and ORAC-PGR, respectively). The effect of the extracts of mango by-products on the oxidation of Trp was evaluated by fluorescence spectroscopy. Data obtained employing the ORAC-FL assay showed a low discrimination of the antioxidant activity of the samples (Peel ≈ Seed > Pulp). However, employing the ORAC-PGR assay it was possible to differentiate the antioxidant activity of the samples (Seed > Peel >> Pulp). Extracts obtained from mango seed, peel, and pulp protected Trp of MP when the latter was exposed to AAPH (2,2′-azo-bis(2-amidinopropane) dihydrochloride)-derived free radicals. Such effect was in good agreement with the ORAC-PGR data, showing that this assay could be employed to predict the protection of Trp residues of MP.     

Solid-state fermentation of red raspberry (Rubus ideaus L.) and arbutus berry (Arbutus unedo, L.) and characterization of their distillates

The aim of the present study was to obtain two distilled alcoholic beverages from red raspberry and arbutus berry by solid-state fermentation and subsequent distillation of the fermented fruits. The mean concentrations of ethanol and volatile substances in the distillates from red raspberry (41.3 and 200.1 g/hL aa) and arbutus berry (44.3 and 267.1 g/hL aa) were higher than the corresponding minimum limits (38.5 and 200 g/hL aa) fixed by the European Council (Regulation 110/2008) for fruit distillates. In addition, the mean concentrations of methanol in the two alcoholic beverages (113.9 g/hL aa in case of red raspberry, and 320.5 g/hL aa in case of arbutus berry) were much lower than the maximum levels of acceptability that the aforementioned regulation fixed for red raspberry (1200 g/hL aa) and arbutus berry (1000 g/hL aa) distillates. These results showed that both fruits can be used as fermentation substrates for producing two alcoholic beverages with high quality, which are safe for the consumers without any repercussion to their health from methanol concentrations.     

Inhibitory effect of Chardonnay and black raspberry seed extracts on lipid oxidation in fish oil and their radical scavenging and antimicrobial properties

Ethanol extracts of Chardonnay grape and black raspberry seed flours were evaluated for their capacity to suppress lipid oxidation, preserve important fatty acids, and inhibit microbial growth. They were also tested for radical scavenging activity against DPPH and peroxyl radicals as reflected in oxygen radical absorbance capacity (ORAC), and total phenolic content (TPC). Both tested seed flour extracts suppressed lipid oxidation and rancidity development in fish oil. Black raspberry seed flour extract significantly reduced the degradation of biologically important n − 3 PUFA under accelerated oxidative conditions. Black raspberry and Chardonnay seed flour extracts at 165 and 160 μg seed flour equivalents/mL, respectively exhibited bacteriocidal activity against Escherichia coli and growth inhibition of Listeria monocytogenes under experimental conditions. Both seed flour extracts exhibited DPPH radical quenching activity and Chardonnay had the stronger ORAC of 663 μmol Trolox equivalents per gram seed flour and the higher TPC of 99 mg gallic acid equivalents/g flour. The data from this study suggest the potential for developing natural food preservatives from these seed flours for improving food stability, quality, safety, and consumer acceptance.     

Antioxidant capacity of herbal infusions and tea extracts: A comparison of ORAC-fluorescein and ORAC-pyrogallol red methodologies

Oxygen radical absorbance capacity (ORAC) values have been obtained for a series of teas and herbal infusions employing 2,2′-azo-bis(2-amidinopropane) as free radical source, and fluorescein and pyrogallol red as target molecules. The amounts of phenols in the extracts were evaluated by Folin’s methodology. ORAC values are extremely dependent upon the employed target molecule. Even more, relative ORAC values measured for different infusions depend upon the employed methodology. For example, ORAC-fluorescein value of Aloysia citriodora is larger than that of green tea, while if pyrogallol red is employed as target molecule green tea appears as nearly nine times more efficient. Similarly, for extracts with comparable amounts of phenols, herbal infusions are more efficient than teas by ORAC-fluorescein, while opposite conclusions are obtained if ORAC-pyrogallol red values are considered. Extreme care must then be taken for conclusions obtained from ORAC values estimated by employing a single target molecule.     

Solid-phase extraction of berries’ anthocyanins and evaluation of their antioxidative properties

Solid-phase extraction (SPE) was used to obtain anthocyanin-rich extracts from five berry species: chokeberry, elderberry, black currant, blackberry and blueberry. During SPE more than 94.4% of the sugars and more than 88.5% of the acids present in the crude extracts were separated. The SPE resulted in 90–95.6% anthocyanins recovery. The antioxidative properties of the anthocyanin-rich extracts were tested by measuring their oxygen radical absorption capacity (ORAC), hydroxyl radical averting capacity (HORAC), total peroxyl radical trapping antioxidant parameter (TRAP), scavenging of nitric oxide and inhibition of lipid peroxidation. Elderberry extract revealed the highest ORAC value of 5783 μmol TE/g. Chokeberry extract was the most potent inhibitor of lipid peroxidation and had the highest TRAP value of 4051 μmol TE/g. Blueberry extract had the highest HORAC result – 1293 μmol GAE/g and was the most powerful scavenger of NO. The high antioxidant activity according to all antioxidant assays revealed opportunities to apply these preparations as antioxidants.     

Anti-oxidant,anti-proliferative and anti-inflammatory activities of the extracts from black raspberry fruits and wine

The purpose of the study was to determine polyphenols, anthocyanins and ascorbic acid in the extracts of black raspberry fruits and wine, along with their anti-oxidant, anti-proliferative and anti-inflammatory activities. Black raspberry fruits without or with seeds crushed were blended in 60% ethanol (FE and FES, respectively) or in water (FW and FWS, respectively). Black raspberry wine without or with seeds crushed (W and WS, respectively) were prepared. Polyphenol content was the highest in the FES (8.25 mg/g fruit). Generally the ethanol extracts with seeds crushed showed higher anti-oxidant activities with the lowest DPPH IC₅₀ (130 μg/ml (freeze-dried extract/reaction solution)) for the FES and the lowest ABTS IC₅₀ (198 μg/ml) for the WS. Cell viabilities were reduced by 13–70% when treated with 100 μg/ml (freeze-dried extract/medium) for HT-29 cells and 1000 μg/ml for LNCaP cells. The FES most actively suppressed nitric oxide production in LPS-stimulated RAW264.7 cells (p < 0.05). Superoxide dismutase and glutathione peroxidase activities treated with the extracts were higher than the control (p < 0.05).     

Enhanced functional properties of tannic acid after thermal hydrolysis

Thermal hydrolysis processing of fresh tannic acid was carried out in a closed reactor at four different temperatures (65, 100, 150 and 200 °C). Pressures reached in the system were 1.3 and 4.8 MPa at 150 and 200 °C, respectively. Hydrolysis products (gallic acid and pyrogallol) were separated and quantified by HPLC. Gallic acid and pyrogallol production was increased (p ? 0.05) when heated to 150 °C. Pyrogallol production reached (p ? 0.05) up to 4.6 mg/ml at 200 °C. Antioxidant activity of processed tannic acid at different temperatures was measured by the Rancimat® method using soybean oil. Processed tannic acid at 200 °C showed a ∼3-fold increase (p ? 0.05) in induction time from ∼7 h for the control. Pyrogallol had higher (p ? 0.05) antioxidant capacity than gallic acid, thus pyrogallol was proven to be one of the major compounds responsible for enhanced antioxidant capacity in processed tannic acid. However, the induction point of processed tannic acid at 200 °C was higher than that of synthetic pyrogallol at higher concentration. This shows that pyrogallol alone is not responsible for the antioxidant capacity of processed tannic acid. A disc diffusion assay showed that tested Gram positive pathogenic strains (Listeria monocytogenes and Staphylococcus aureus) were more (p ? 0.05) sensitive (40–51 mm) to processed tannic acid than Gram negative pathogens (22.8–26.8 mm). Regardless of bacterial species, pyrogallol also showed higher antimicrobial activity than gallic acid. Simple thermal processing of hydrolyzable tannic acid could be used to produce gallic acid and pyrogallol with enhanced antioxidant and antimicrobial capacity.     

Quantification of phenolic contents and antioxidant capacity of Atlantic sea cucumber, Cucumaria frondosa

The antioxidant activity (oxygen radical absorbance capacity, ORAC) and total phenols and flavonoids were determined in extracts from digestive tract, gonads, muscles and respiratory apparatus of sea cucumber, Cucumaria frondosa. Total phenols content varied from 22.5 to 236.0 mg of gallic acid equivalents/100 g dw, and flavonoids from 2.9 to 59.8 mg of rutin equivalents/100 g. ORAC values ranged from 140 to 800 μmol of Trolox equivalents/g dw. Among all extracts, best antioxidant potencies were observed in ethyl acetate extracts from digestive tract, and in acetonitrile-rich fractions obtained from mixed extracts using acetonitrile/TFA (trifluoroacetic acid) acidified water on muscles, gonads and respiratory apparatus. The weakest potencies were observed with water extracts from digestive tract and respiratory apparatus, and with water-rich fractions obtained from mixed extraction of gonads and muscles. A significant correlation was observed between ORAC values and total phenol content in extracts and fractions of gonads and muscles, but ORAC and phenols were not correlated in digestive tract and respiratory apparatus extracts. ORAC values were significantly correlated (p < 0.05) with total flavonoids in all extracts. Successive eluates obtained from solid-phase extraction of water-rich fractions using C₁₈ cartridge showed ORAC values (105–500 μmol of TE/g) reaching up to 2.3 times the potency of their parent fractions. Flavonoids are suggested to be mainly responsible for observed activities. Our results provide a first quantitative evaluation of C. frondosa tissues as useful sources of antioxidants for human consumption.     

Microwave-assisted extraction of phenolic antioxidant compounds from peanut skins

A microwave-assisted extraction system was used to extract phenolic antioxidants from peanut skins. The effects of microwave power (10%, 50%, 90% nominal), irradiation time (30, 90, 150 s) and sample mass (1.5, 2.5, 3.5 g) on total phenolic content (TPC), ORAC (oxygen radical absorbance capacity) level and resveratrol content of peanut skin extracts (PSE) were investigated. Peanut skins were extracted with 37.5 ml of 30% ethanol (EtOH) in water. A response surface method was used to estimate optimum extraction conditions, based on TPC, ORAC level and resveratrol content. The maximum predicted TPC, under the optimised conditions (90% microwave power, 30 s irradiation time and 1.5 g skins), was 143.6 mg gallic acid equivalent (GAE)/g skins. The highest ORAC value was 2789 μmol trolox equivalents (TE)/g skins, which occurred at 90% power, 150 s and 1.5 g of skins. Resveratrol was identified in PSE by LC–MS–MS analysis.     

Pomological features, nutritional quality, polyphenol content analysis, and antioxidant properties of domesticated and 3 wild ecotype forms of raspberries (Rubus idaeus L.)

Abstract: The raspberry (Rubus idaeus L.) is an economically important berry crop that contains many phenolic compounds with potential health benefits. In this study, important pomological features, including nutrient content and antioxidant properties, of a domesticated and 3 wild (Yayla, Yavuzlar, and Yedigöl) raspberry fruits were evaluated. Also, the amount of total phenolics and flavonoids in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were calculated as gallic acid equivalents (GAEs) and quercetin equivalents (QE). The highest phenolic compounds were found in wild Yayla ecotype (26.66 ± 3.26 GAE/mg extract). Whilst, the highest flavonoids were determined in wild Yedigöl ecotype (6.09 ± 1.21 QA/mg extract). The antioxidant activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were investigated as trolox equivalents using different in vitro assays including DPPH^?, ABTS^?+, DMPD^?+, and O^??₂ radical scavenging activities, H₂O₂ scavenging activity, ferric (Fe³⁺) and cupric ions (Cu²⁺) reducing abilities, ferrous ions (Fe²⁺) chelating activity. In addition, quantitative amounts of caffeic acid, ferulic acid, syringic acid, ellagic acid, quercetin, α‐tocopherol, pyrogallol, p‐hydroxybenzoic acid, vanillin, p‐coumaric acid, gallic acid, and ascorbic acid in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were detected by high‐performance liquid chromatography and tandem mass spectrometry (LC‐MS‐MS). The results clearly show that p‐coumaric acid is the main phenolic acid responsible for the antioxidant and radical scavenging activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits.     

Antioxidant effect of oregano (Lippia berlandieri v. Shauer) essential oil and mother liquors

The conventional steam distillation process for oregano (Lippia berlandieri v. Shauer) essential oil extraction produces large volumes of mother liquor. This residual liquid represents a potential value because the soluble antioxidants it contains. Essential oil and ethyl acetate mother liquor extracts (MLEs) were evaluated for antioxidant activity. Total phenolic content and antioxidant activities by the 2-2′-diphenyl-1-picrylhydrazyl (DPPH) method, by the deoxyribose degradation assay, and by oxidation of low density lipoproteins (LDL) with CuSO₄ were evaluated. Oil yield was 4.34%. Total phenolic content was 151 ± 2.00 and 150.5 ± 0.98 mg of GAE (gallic acid equivalents)/mL for the essential oil and MLEs, respectively. DPPH assay showed a low radical scavenging activity (RSA) for oregano essential oil. Meanwhile MLEs exhibited no significant RSA at low concentrations, but at higher concentrations (100 μg/mL), it was superior to those exhibited by the controls ascorbic acid and butylated hydroxytoluene (BHT). Deoxy-d-ribose assay results for both essential oil and MLEs showed a good hydroxyl radical RSA at the concentrations tested. Essential oil and MLEs delayed induction time effectively. Solubility problems, chemical constituents, and their hydrophilic–lipophilic distribution are key factors that explain samples behavior for an eventual use of these natural products.     

Effect of storage on refined and husk olive oils composition: Stabilization by addition of natural antioxidants from Chemlali olive leaves

Two samples of refined olive and husk oils have been analysed in order to evaluate the influence of storage time on their quality. The following parameters were determined: peroxide values, absorption coefficients K270 and K232, Rancimat induction time, sterols and fatty acid contents. Six months storage at 50 °C in the dark revealed a loss in oil stability. This finding was reflected by the greater increase in peroxide value and a decrease of Rancimat induction time and sterol content. The enrichment of refined olive and husk oils with olive leaves and its hydrolysate extract resulted in an appreciable resistance to oxidative deterioration due to its phenolic antioxidants content. Oleuropein and hydroxytyrosol were the major compounds in Chemlali olive leaves extract and hydrolysate solution, respectively. The antiradical activity of leaves extract as well as its hydrolysate solution was evaluated and compared to that of the BHT. The antioxidant activity of the enriched refined olive and husk oils with leaves and hydrolysate extracts at 400 ppm showed that the latter had the highest protective effect against oil oxidation. Oils with added hydrolysate extract had the lower peroxide value and the higher stability measured with a Rancimat method. After six months of storage the induction time increased from 23.3 to 83.5 h for refined olive oil and from 16.6 to 49 h for husk oil. Furthermore, during oil storage, there was no significant variation in fatty acid composition. However, the total sterol concentration of the oils treated with hydrolysate extract increased. The results suggested that hydrolysate and leaves extracts are excellent antioxidants and can serve as substitutes for synthetic antioxidants.     

Changes in bioactive compounds and antioxidant capacity of fresh-cut cashew apple

In this study, ascorbic acid, total polyphenols and proanthocyanidins of fresh-cut cashew apple were quantified. Antioxidant capacity was determined in whole juice and in polyphenols extracts by three methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ??-carotene bleaching. Effect of cutting and storage for 24 h at 2 °C, 27 °C and 40 °C on these compounds were also evaluated. Cashew apple presented 163 mg of ascorbic acid per 100 g of fresh weight (FW). Soluble and hydrolysable polyphenols contents were 12.79 mg GAE/100 g FW and 18.53 mg GAE/100 g FW and proanthocyanidins were 9.27 mg/100 g FW. Antioxidant capacity of juice and polyphenols extract was high for DPPH method. Storage temperatures affected bioactive compounds on cut cashew apple. The content of ascorbic acid decreased in all temperatures. Proanthocyanidins were more sensitive to 40 °C than to other temperatures. The content of polyphenols and antioxidant capacity of juice by DPPH assay did not change. However, the reducing power was lower in samples kept at high temperatures. A strong positive correlation between ascorbic acid and FRAP (r = 0.99) and a negative correlation between DPPH and FRAP (r = − 0.79) were observed. No correlations were found between polyphenols and antioxidant capacity indicating the importance of phenolic composition in the extracts. The results confirm the importance of temperature and injury on the quality of cashew apple.     

Electrochemical behaviour and antioxidant capacity of anthocyanins from Chilean red wine,grape and raspberry

The anthocyanin fractions were extracted from Cabernet Sauvignon red wine, skins of Vitis vinifera grapes and raspberry fruits (Rubus idaeus). In red wine extract, 16 anthocyanins were identified, malvidin-3-O-glucoside being the main anthocyanin, which comprised 53.6% of the total anthocyanin in grape extract. Raspberry extract contained mainly delphinidin-3-O-glucoside and cyanidin-3-O-glucoside. The antioxidant capacity of the extracts was assayed by electrochemical methods. Best resolution of the oxidation peaks for the extracts and diluted wine was obtained by pulse differential voltammetry. The wine diluted 20× presented values of P1 (443 mV) and P2 (676 mV) similar to those corresponding to wine extract, and to the anthocyanin malvidin-3-O-glucoside. The antioxidant capacity of anthocyanins in extracts of wine, grape skin and raspberry fruit was also determined by the Trolox equivalent antioxidant capacity (TEAC) method.     

Mycosporine-like amino acid composition of the edible red alga, Palmaria palmata (dulse) harvested from the west and east coasts of Grand Manan Island,New Brunswick

The oxygen radical absorbance capacity (ORAC), antiproliferative activities and mycosporine-like amino acid (MAA) profiles of methanol extracts from two grades of dulse harvested from locations varying in UV-exposure (west vs east coasts of Grand Manan Island, NB) were determined in the present study. MAAs confirmed by LC/MS in both grades 1 (low-UV) and 2 (high-UV) dulse were palythine, shinorine, asterina-330, palythinol and porphyra-334; usujirene was present only in grade 2 dulse. ORAC values of grade 1 and 2 dulse extracts were 36.42 and 38.78 μmol Trolox/g extract. B16-F1 murine skin melanoma cell proliferation was inhibited (p < .05) by 68.5% and 91.9% by grade 1 and 2 dulse extracts at 6.0 mg/mL. The antiproliferative efficacy of grade 2 dulse was greater (p < .05) than grade 1 from 0.375 to 6.0 mg/mL. MAA differences between the grade 1 and 2 dulse extracts likely influenced the antiproliferative efficacies, despite the similar ORAC values.     

The antioxidative properties of mustard leaf (Brassica juncea) kimchi extracts on refrigerated raw ground pork meat against lipid oxidation

The efficacy of varying concentration of mustard leaf kimchi ethanolic extracts (MK) in retarding oxidative rancidity was tested with raw ground pork. Freshly ground pork meat was assigned to one of the following five treatments: control (no antioxidants); AC-0.02 (0.02% ascorbic acid); MK-0.05, 0.1, and 0.2 (0.05%, 0.1% and 0.2% MK, respectively). The pH of the samples decreased and the TBARS values and free fatty acids (%) increased considerably (P < 0.05) during storage. The total bacterial count was lower in MK-0.1 and MK-0.2 than the control during storage. The internal L∗ value and a∗ value decreased (P < 0.05) with the addition of MK. The internal b∗ value of MK treatments were higher (P < 0.05) than that for the control and increased incrementally with MK concentration. The TBARS values and free fatty acids (%) of MK-0.02 was lowest among the treatments. The peroxide value of the control increased until 7 days and reached the maximum value at a certain storage time and decreased thereafter. In the other treatments it increased. All treatments had lower concentration of conjugated dienes (P < 0.05) compared to the control sample, after the first day. Mustard leaf kimchi ethanolic extracts exhibited a protective effect against lipid oxidation in raw ground pork.     

Microwave-assisted extraction of phenolic compounds from wine lees and spray-drying of the extract

Most research on extraction of phenol compounds from wine by-products and commercial exploitation of extracts use grape seeds and/or skins as raw materials. Looking for alternative antioxidants sources, obtaining antioxidant extracts from wine lees (also known as dregs), a sub-exploited by-product of winemaking process, is here presented. Microwave-assisted extraction (MAE) of phenolic compounds from wine lees has been optimized using the total phenols index, the ORAC values and yield of the extraction as response variables. Under the optimal working conditions, the proposed MAE method provides better extraction efficiency in a much shorter time (17 min) than the conventional extraction method for phenolic compounds (24 h). The liquid extract obtained by MAE was spray-dried. The type and amount of excipients used, as well as the spray-drying temperature, were optimized in order to minimize the oxidation of phenolic compounds and maximize the yield of the spray-drying process. The total phenols index in the dried extract thus obtained was 36.8% (expressed as gallic acid), showing an ORAC value of 3930 μmol TE/g. Additionally, Mv3G, Cm-Mv3G, myricetin, quercetin, quercetin-3-β-glucoside, caffeic acid and p-coumaric acid were quantified in the dry extract by HPLC–DAD. The results indicate that wine lees antioxidant extracts can be a suitable and cheap alternative to those obtained from grape seeds or skins.     

Ascorbic acid enrichment of whole potato tuber by vacuum-impregnation

The aim of this study was to evaluate the use of vacuum-impregnation (VI) for enriching the ascorbic acid content of whole potatoes. Whole potatoes were immersed in a 10% ascorbic acid (AA) solution. A vacuum pressure of 70 cm Hg was applied for 0–60 min, following atmospheric pressure restoration for 3 h, while samples remained in the VI solution. AA concentrations of potatoes were measured using HPLC. The effects of cooking and storage time in subsets of the fortified samples were also evaluated. Results indicated that the AA concentration of whole potatoes increased with vacuum time (max 150 mg/100 g fr. wt.). In addition, a steam-cooking study showed that 100 g of the 25 min steam-cooked VI potatoes could provide adults with 90–100% of the recommended daily allowance of AA (100 mg). The storage study showed that VI whole potatoes had a relatively high AA concentration (50 mg/100 g fr. wt.), even at 14 days of storage at 4 °C. This study indicated that VI treatment of whole potatoes was useful for enriching the AA content.