Grape By-products Research Articles

Low molecular weight phenolics of grape juice and winemaking byproducts: antioxidant activities and inhibition of oxidation of human low-density lipoprotein cholesterol and DNA strand breakage.

Bioactive compounds belonging to phenolic acids, flavonoids, and proanthocyanidins of grape juice and winemaking byproducts were identified and quantified by HPLC-DAD-ESI-MS(n). The concentration of phenolic compounds in different grape cultivars was in the order Tempranillo > Cora > Syrah > Isabel. The insoluble-bound fraction was most prominent, contributing 63 and 79% to the total for Isabel and Tempranillo, respectively. Juice-processing byproducts had a higher content of free than esterified phenolics, but the opposite was noted for winemaking byproducts. Insoluble-bound phenolics were up to 15 and 10 times more effective as antioxidants than those of free and esterified fractions, respectively, as evaluated by the DPPH, ABTS, and H2O2 scavenging activities and reducing power determinations. In general, insoluble-bound phenolics (100 ppm) were more effective in inhibiting copper-induced human LDL-cholesterol oxidation than free and esterified phenolics, exhibiting equal or higher efficacy than catechin. Phenolic extracts from all fractions inhibited peroxyl radical-induced DNA strand breakage. These findings shed further light for future studies and industrial application of grape byproducts, which may focus not only on the soluble phenolics but also on the insoluble-bound fraction.

Effect of the drying process on the intensification of phenolic compounds recovery from grape pomace using accelerated solvent extraction.

In light of their environmental and economic interests, food byproducts have been increasingly exploited and valorized for their richness in dietary fibers and antioxidants. Phenolic compounds are antioxidant bioactive molecules highly present in grape byproducts. Herein, the accelerated solvent extraction (ASE) of phenolic compounds from wet and dried grape pomace, at 45 °C, was conducted and the highest phenolic compounds yield (PCY) for wet (16.2 g GAE/100 g DM) and dry (7.28 g GAE/100 g DM) grape pomace extracts were obtained with 70% ethanol/water solvent at 140 °C. The PCY obtained from wet pomace was up to two times better compared to the dry byproduct and up to 15 times better compared to the same food matrices treated with conventional methods. With regard to Resveratrol, the corresponding dry pomace extract had a better free radical scavenging activity (49.12%) than the wet extract (39.8%). The drying pretreatment process seems to ameliorate the antiradical activity, especially when the extraction by ASE is performed at temperatures above 100 °C. HPLC-DAD analysis showed that the diversity of the flavonoid and the non-flavonoid compounds found in the extracts was seriously affected by the extraction temperature and the pretreatment of the raw material. This diversity seems to play a key role in the scavenging activity demonstrated by the extracts. Our results emphasize on ASE usage as a promising method for the preparation of highly concentrated and bioactive phenolic extracts that could be used in several industrial applications.

Natural compounds from grape by-products enhance nutritive value and reduce formation of CML in model muffins

This study had the objective of determining the effects of the addition of different ingredients and grape by-products (GP) to muffins on CML content. It was found that ingredients, such as salt, baking powder and protein-rich components, reduced CML from 50% to 86%. The use of all ingredients simultaneously caused the highest reduction in CML, suggesting synergistic effects in the muffin formula. Raw cane sugar produced higher amounts of CML than refined sucrose, probably due to metal-ion mediated degradation of fructoselysine. The CML content was correlated with the level of oleic acid at −0.829 and with the level of linoleic acid at 0.913. Muffins enriched with appropriate levels of GP (20%) showed a lowering of the CML level and no significant changes in the sensory profile. GP added to the model system with protein-rich ingredients resulted in the weakest inhibitory effects, probably due to the polyphenol–protein binding mechanism.

WINERY WASTE MANAGEMENT IN SERBIA: VRANAC GRAPE MARC AS SOURCE OF ANTIOXIDANTS

During winemaking of grape, large quantities of waste are produced. For example, by processing 100 kilograms of grape-vine approximately 20 25 kilograms of grape marc is produced. The placing of the enormous amount of waste grape (around 5 9 million tons per year) generated in all over the world is an increasing environmental problem. In recent years, the growing concern about the environment has led authorities to look for economically viable solutions for recycling and/or valorizing grape waste. Serbia is one of the major producers and consumers of grapes and wine in the Western Balkans, with a grape and wine production 330,070 tonnes and 1,700,000 hl of which remains about 7,000 tons of secondary products. Significant amounts of polyphenols found in grape, wine and grape by-products and a great interest in their exploitation. In this work, the content of polyphenols and antioxidant activity Vranac Vitis vinifera L. grape marc after obtaining red wine were investigated. Our results of analysis of grape waste show significant content of polyphenols reflecting their exellant antioxidant activity. It was concludes that the grape marc constitutes a very cheap source for the extraction of phenolic antioxidants, which can be used in food and pharmaceutical industries, thus providing an important economic advantage.

Optimization of Extraction of Bioactive Compounds from Different Types of Grape Pomace Produced at Wineries and Distilleries

Natural extracts obtained from grape pomace are particularly interesting, due to the substantial variety of valuable compounds present with health benefits, specifically phenolic compounds such as anthocyanins, trans-resveratrol, quercetin, and proanthocyanidins. The production of such extracts has been recognized as a profitable way to valorize grape byproducts, which are low-value and most abundant. First, the effect of the solvent on the extraction of bioactive compounds from grape pomace is studied. The selected solvents are water and ethanol, biocompatible and available in wineries and distilleries. Then, different types of grape pomace obtained along the various stages of current industrial winemaking and distillation processes are analyzed. As a result, the best stage of the winemaking and distillation processes for pomace valorization is identified, corresponding to the grape byproduct with the highest potential as source of bioactive compounds. These studies were performed with Vitis vinifera variety of Tempranillo grapes (same year, same vineyard). This work optimizes the production of natural extracts from (byproduct) grape pomace with recognized health benefits, to be used as high value nutraceuticals ingredients. The process proposed uses renewable and low-cost resources existent in wineries and distilleries. The select solvent extracting is a mixture of the biocompatible water and ethanol. The selected fermented grape pomace was chosen from different and comparable types of grape pomace obtained at current winemaking and distillation processes, to be used in extraction without any pretreatment.

Detailed phenolic composition of white grape by-products by RRLC/MS and measurement of the antioxidant activity

The development and validation of a rapid method of RRLC has been carried out to determine the phenolic composition of winemaking by-products (pomaces, seeds, skins and stems). Thirty-one phenolic compounds belonging to three groups (flavanols, flavonols and phenolic acids) have been identified by use of standards and mass spectrometric detection, and quantified by using the corresponding external standard calibration plot, in a 16-min run. The validation was realized calculating the repeatability, the reproducibility and the limits of detection (LOD) and quantification (LOQ), from standards solutions. The limits of detection and quantification were in the range of 0.16–1.09 and 0.52–3.63mg/L, respectively, and good repeatability (R.S.D. values <1.5%) and reproducibility (R.S.D. values <5.5%) were found. Results confirmed that the method is effective and suitable for determination of phenolic compounds in winemaking by-products. Seeds, skins, stems and pomaces exhibited a different qualitative and quantitative phenolic profile and different antioxidant activities.

Impact of Adding White Pomace to Red Grapes on the Phenolic Composition and Color Stability of Syrah Wines from a Warm Climate

The influence of the fermentative addition of Pedro Ximenez grape pomace (PXGP, white variety) on the phenolic composition and color of Syrah red wines from a warm climate was studied. Changes on phenolic composition (HPLC), copigmentation/polymerization (spectrophotometry), and color (tristimulus colorimetry) allowed differences among the maceration treatments to be established. PXGP additions at the rates studied increased the extraction of total phenolics, phenolic acids, and monomeric flavanols. However, the effect on the anthocyanins, copigmentation, and polymerization depended on the doses applied, with important consequences on the color. PXGP addition at 10% led to wines with higher polymerization, more stable colors, and bluish hues. in contrast, perceptibly lighter and less intense wines were obtained with PXGP addition at 20%. Thus, the use of white grape byproducts as wine additives at appropriate levels (10% w/w) could improve the phenolic potential of red young wines from a warm climate, contributing to preserve their color characteristic.

Multiple Response Optimization of High Temperature, Low Time Aqueous Extraction Process of Phenolic Compounds from Grape Byproducts

In this study phenolic compounds extraction from grape byproducts was conducted using pure water as a solvent. High temperatures and low time incubation periods were used in the aim of reducing the cost of the process and heightening the phenolic compounds yield. Response surface methodology (RSM) was realized to study the effect of time and temperature on crushed and uncrushed grape pomace. The phenolic content was evaluated considering the quantity (total phenolics (TPC), flavonoids (FC), total monomeric anthocyanins (TMA) and tannins (TC)), and quality (antiradical activity (AA) and antioxidant capacity (AC)) of the extracts. High temperature low time extraction design used in this study was compared to the extraction process at moderate temperatures with relatively long periods of time. This was proved to ameliorate the quantitative extraction of phenolic compounds from grape pomace without affecting their bioactivity. Moreover, multiple response optimization showed the optimal extraction parameters to be 81?C and 140 minutes for the unmilled pomace samples, and 88?C and 5 minutes for the milled. TPC, FC, TMA, TC, AA and AC are almost the same for both optimums. Thus the possibility of replacing the milling process by the extraction time prolongation (for the unmilled pomace) of 135 minutes seems to be very plausible. HPLC analysis showed different quantity and diversity of extracted phenolics for the optimums. However this difference did not significantly affect the overall activity, showing that PC in the different extracts act in complete synergy all together leading to important biological properties. The obtained results using the extraction strategy adopted in this work could lead to several industrial applications.

Extraction of Total Phenolic Compounds, Flavonoids, Anthocyanins and Tannins from Grape Byproducts by Response Surface Methodology. Influence of Solid-Liquid Ratio, Particle Size, Time, Temperature and Solvent Mixtures on the Optimization Process

The current work concerns the optimization process of phenolic compounds solid liquid extraction from grape byproducts at high temperatures and short incubation times. The effect of five experimental parameters (solidliquid ratio, particle size, time, temperature and solvent mixture) mostly believed to affect the extraction process was undertaken. A first response surface methodology experimental design was used to optimize the solid-liquid ratio and milling time parameters. A second design was used for the optimization of the quantitative and qualitative parameters. The quantitative parameters studied are: total phenolic compounds, flavonoid content, total monomeric anthocyanin composition and tannin concentration. The qualitative parameters analyzed are: antiradical activity and antioxidant capacity. The second design was based on the use of time, temperature and solvent mixture as optimization parameters. The assays were first conducted separately revealing the best experimental conditions for the maximization of each response variable alone. A simultaneous response surface methodology of all the responses taken together was then conducted, showing the optimal extraction conditions to be: 93 minutes at 94?C and in 66% ethanol/water solvent. The maximal response values obtained for each parameter are: Total Phenolic Compounds yield (5.5 g GAE/100g DM), Flavonoid Content (5.4 g GAE/100g DM), Total Monomeric Anthocyanin yield (70.3 mg/100g DM), Tannin Concentration (12.3 g/L), Antiradical Activity (67.3%) and Total Antioxidant Capacity (393 mgAAE/L). All of the optimal values were acquired at 3 mL/g solid-liquid ratio and 6.8 min milling time. The obtained extracts could be used as natural bioactive compounds in several industrial applications.

Polyphenols composition of wine and grape sub-products and potential effects on chronic diseases

Grape (Vitis vinifera) is one of the most cultivated fruit crops in the world, with an approximate annual production of ∼64 million metric tons in 2010 (OIV, 2011). Grapes composition in polyphenols and their extractability which is far from complete and typically reaching only 30–40% depend on grape varieties, vineyard location and the technological parameters during wine making process including destemming, crushing, maceration and pressing. Therefore, grape pomace potentially constitutes a very abundant and relatively inexpensive source of a wide range of polyphenols including monomeric and oligomeric flavan3-ols (proanthocyanidins) as well as anthocyanins (glucosides, acetylated glucosides and coumarylic glucosides). Moreover, it has been evaluated as a potential source of antioxidant polyphenols which could be used as nutraceuticals or food additives. Actually, phenolic compounds are known to have some health benefits such as a chemopreventive role toward cardiovascular, cancer, and degenerative diseases. In order to valorize wine by-products from Rhone Valley area, grape and pomace seeds and skins from red wine cultivars at maturity from the vintage 2009 and 2010 (Grenache, Syrah, Carignan, Mourvedre, Counoise and Alicante) have been characterised for their phenolic contents (total phenol contents, tannin and anthocyanin contents total and individuals; quantification of monomeric and oligomeric proanthocyanidins as well as some anthocyanins (glucosides, acetylated glucosides and coumarylic glucosides)). Ratio of initial phenolic compounds from grape to pomace was also estimated. The comparison of several wine industry by-products with their respective grapes provided evidence that grape seed and skin pomace extracts still contained appreciable amounts of flavanol-3-ols and anthocyanins even after the fermentation process. Quantitative and qualitative distribution of polyphenols in grape pomaces showed significant differences through varieties. Seed extracts from grapes and pomaces contain exceptionally high amounts of total polyphenols than skin’s extracts. This study evidenced seeds from Grenache, Syrah and Alicante and skins from Syrah, Carignan and Alicante as the most interesting fractions to be valorized because of their richest contents in polyphenols compared to the other assessed fractions and varieties. This work further supports that grape pomaces obtained after vinification still retained a significant amount of polyphenols of which level depends largely on the vintage. The use of this by-product would constitute a promising natural source of available polyphenols which could be included in nutraceutical formulation. Activity effects of grape by-products on a chronic disease model with hypertension are given. ∗Corresponding author: Pierre-louis Teissedre, Universite Bordeaux Segalen, Institut des Sciences de la Vigne et du Vin, EA 4577USC Oenologie 1366 INRA-UBS-IPB, 210, chemin de Leysotte, CS 50008, 33882 Villenave d’Ornon Cedex, France. E-mail: p.teissedre@u-bordeaux2.fr.

Protective effect of grape by‐product‐fortified breads against cholesterol/cholic acid diet‐induced hypercholesterolaemia in rats

New breads fortified with two different forms of grape by-products, namely dried powdered skins (PGP) and freeze-dried extract therefrom (EGP), were characterised and their protective effect against hypercholesterolaemia in rats was studied. The phenolic compound profiles of supplemented breads were dominated by epicatechin and catechin together with appreciable amounts of dimeric procyanidins. Sensory evaluation of enhanced breads revealed that a maximum of 6% PGP or 1.4% EGP could be incorporated to prepare acceptable products. Intake of high-cholesterol/cholic acid diet containing 6% PGP- or 1.4% EGP-fortified bread increased fresh stool weight and significantly reduced protein and fat digestion but did not negatively affect animal growth. PGP- and EGP-fortified breads diminished the negative impact of high-cholesterol/cholic acid diet, lowering total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), lipid peroxidation, glucose and leptin levels, preventing visceral fat accumulation and increasing high-density lipoprotein cholesterol and plasma ferric-reducing antioxidant power levels. Since control bread feeding significantly lowered TC, LDL-C and lipid peroxidation compared with high-fat diet, it may suggested that not only grape by-products but also another components in bread were related to lipid metabolism. These results demonstrate that intake of both PGP- and EGP-fortified sourdough mixed rye breads might contribute to a reduction of cardiovascular risk.

Phenolic compounds, antioxidant activity and insulinotropic effect of extracts prepared from grape (Vitis vinifera L) byproducts.

Grape byproducts are a rich source of phenolics having immense medicinal properties, but usually wasted from juice/wine processing industries. The present study investigates the phenolic antioxidants and the insulinotropic effect of extracts prepared from seed, skin and stems of two red wine grape cultivars: Pusa Navarang and Merlot. Pusa Navarang cultivar has shown high amounts of total phenolics (95.8mg/ml), flavonoids (30.5mg/ml) and flavan-3-ols (21.8mg/ml) in seed extract and total anthocyanin (4.9mg/ml) in its skin extract as compared to Merlot cultivar. As determined using HPLC, higher amounts of catechin hydrate (14909mg/l) and epicatechin (9299mg/l) were observed in its seed extract, while quercetin hydrate (5849mg/l) was abundant in its skin extract. Similarly, ferric reducing antioxidant power (FRAP) and ABTS(+). [2,2'-azinobis (3-ethylbenzothiazoline)-6-sulfonic acid] and DPPH. (1,1-diphenyl-2-picrylhy- drazyl) radicals scavenging, were higher in its seed extract, respectively being 134.8mg/ml of Quercetin equivalent (QE), 18.7mM of trolox equivalent (TE) and 33.5mM of TE. Strong correlation was obtained between FRAP and total phenolics, flavonoids and flavan-3-ols contents with correlation coefficients (r(2)) of 0.915, 0.738 and 0.838 respectively. Interestingly, there was a 2-8 fold increase in insulin secretion by isolated mice pancreatic islets at 5.5mM and 16.5mM glucose concentration in presence of various extracts. Overall, the seed, skin and stem byproducts of both cultivars are rich sources of phenolics and antioxidants and represent a source of new insulin secretagogues.

An Environment Friendly, Low-Cost Extraction Process of Phenolic Compounds from Grape Byproducts. Optimization by Multi-Response Surface Methodology

Due to their beneficial effects on human health, phenolic compounds are increasingly attracting the attention of scientists and researchers all over the world. The main interest is in the extraction process of those natural plant-originated compounds from fruits, vegetables and plant wastes, namely grape wastes, in which phenolic compounds are the most abundant secondary metabolites. This waste exploitation not only re-assimilates those byproducts into the food cycle, but also avoids major environmental problems. Herein, the optimization of the phenolic compounds concentration and free radical scavenging activity from Cabernet Sauvignon grape byproducts was conducted, using multi-response surface methodology. A conventional solid-liquid extraction process was performed with pure water as a solvent to study the effects of both time and temperature on the procedure. The maximal phenolic compounds concentration (878.9 mg/L) was reached at 47℃ after 30 hours while the optimal free radical scavenging activity (41.15%) was obtained at 30℃ after 20 hours. A multi-response surface methodology compromised between the quantity and the quality of the extracted phenolics, and the parameters maximizing both responses were obtained at 37℃ and 28 hours. This low-cost and energy saving process provides an excellent tool for further industrial applications.

Effect of Different Drying Methods and Storage Time on the Retention of Bioactive Compounds and Antibacterial Activity of Wine Grape Pomace (Pinot Noir and Merlot)

The effects of different drying methods (40 °C conventional and vacuum oven, 25 °C ambient air and freeze dry) on the stability of two red wine grape (Pinot Noir, PN and Merlot, M) byproducts, pomace containing skins and seeds (P) and pomace containing skins only (S) were investigated. Freeze dried samples retained the highest bioactive compounds with total phenolic content (TPC) of 21.19-67.74 mg GAE/g d.m., anthocyanin content (ACY) of 0.35-0.76 mg Mal-3-glu/g d.m., DPPH antiradical scavenge activity (ARS) of 22.01-37.46 mg AAE/g d.m., and total flavanol content (TFC) of 30.16-106.61 mg CE/g d.m., followed with ambient air dried samples. All samples lost significant amount of bioactive compounds during 16 wk of storage at 15 ± 2 °C, in which ambient air and freeze dried samples had TPC reduction of 32-56% and 35-58%, respectively, but ARS in PN-P and M-P still remained more than 50 mg TE/g d.m. Overall, TPC, ARS, and TFC were higher in PN than in M, and higher in pomace than in skins, while reverse results were observed in ACY. Pomace extracts showed higher antibacterial efficiency against Listeria innocua ATCC 51142 than Escherichia coli ATCC 25922 with minimal inhibition concentration (MIC) of 3%, 6%, 4%, and 9% against E. coli, and 2%, 7%, 3%, and 8% against L. innocua for PN-P, PN-S, M-P, and M-S samples, respectively. Dietary fiber content of samples was 57-63% of total dry matter. This study demonstrated that Pinot Noir and Merlot pomace are good sources of antioxidant dietary fibers and may be incorporated into various food products as a functional ingredient. Practical Application: Wine grape pomace (WGP), the byproduct of wine making, is a good source of polyphenols and dietary fibers and may be incorporated into various food products as a functional ingredient. This study reported the effect of four drying methods and storage at 15 ± 2 °C up to 4 months on the retention of polyphenols and antioxidant activity in two types of red WGP (with and without seeds). Antibacterial activity, dietary fiber content and the basic physicochemical properties of dried pomace powder were also reported. The information is essential for developing specific applications of the pomace.

White grape pomace as a source of dietary fibre and polyphenols and its effect on physical and nutraceutical characteristics of wheat biscuits

Grapes are one of the world's staple fruit crops, with about 80% of the yield being utilised for winemaking. Since grape by-products still contain large amounts of secondary metabolites, uses other than as fertilisers might be appropriate. In this study, white grape pomace (WGP) was incorporated in wheat flour at levels of 10, 20 and 30% (w/w) to investigate its influence on rheological, nutraceutical, physical and sensory properties. Farinograph characteristics of dough with different levels of WGP showed a decrease in water absorption from 56.4% (0% WGP) to 45.9% (30% WGP). Addition of WGP reduced hardness and caused a deterioration in brightness and yellowness of all enriched samples. The smallest addition of WGP (10%) caused an approximately 88% increase in total dietary fibre content as compared with the control. The content of phenolic compounds increased from 0.11 mg g⁻¹ with 0% WGP to 1.07 mg g⁻¹ with 30% WGP. The most stable phenols were as follows: γ-resorcylic acid < gallic acid < tyrosol < catechin < isovanilic acid. An assay of radical-scavenging activity showed that WGP addition greatly enhanced the antioxidant properties of biscuits. Acceptable biscuits were obtained when incorporating 10% WGP. WGP might be utilised for the novel formulation of biscuits as an alternative source of dietary fibre and phenols.

Changes in polyphenol and polysaccharide content of grape seed extract and grape pomace after enzymatic treatment

Grape seed extract and grape pomace are rich sources of polyphenols. The aim of this study was to evaluate the release of polyphenols, the solubilisation of carbohydrate, and the antioxidant capacity of these grape by-products after enzymatic reaction with carbohydrases (cellulolytic and pectinolytic activities) and tannase for 24h. The use of tannase in these by-products, and pectinase in grape pomace changed the galloylated form of catechin to its free form, releasing gallic acid and increasing the antioxidant activity. In grape pomace, cellulase treatment was not efficient for phenolic release and antioxidant activity improvement. The addition of carbohydrases to grape pomace, either alone or in combination, degraded the cell wall polysaccharides, increasing the content of monosaccharides. These results provide relevant data about the potential of pectinase, tannase and combinations of enzymes on the release of polyphenols and monosaccharides from grape by-products, improving the antioxidant capacity and the nutritional value.

Use of grape by‐product as a source of dietary fibre and phenolic compounds in sourdough mixed rye bread

SummaryThe study evaluated the effect of grape by‐products (GP) on the chemical composition, soluble (SDF) and insoluble (IDF) dietary fibre, phenolic compounds and antioxidant activity (AA) and organoleptic characteristics of sourdough mixed rye bread. The following samples of sourdough mixed rye bread were prepared: control bread (BC) and breads with GP at four different levels: 4%, 6%, 8% and 10%. Addition of GP significantly improves dietary fraction contents, as bread with a 10% addition of GP accounts for 39% and 37% higher contents of IDF and SDF than BC. The assay of radical‐scavenging activity and reducing ability showed that GP addition greatly enhanced antioxidant properties of mixed rye breads. Profiles of phenolic compounds of supplemented breads were dominated by procyanidin B1 and B2, catechin, epicatechin, caffeic acid and myricetin. With an increase in the level of GP, the hardness and gumminess of the bread significantly increase. Although both BC and supplemented breads showed common volatile compound profiles, there were slight differences in the concentrations of those components. Sensory evaluation of GP‐enhanced breads revealed that a maximum of 6% GP could be incorporated to prepare acceptable products.

건조방법과 감마선 조사에 따른 포도가공부산물의 색상 변화 및 항산화활성

본 연구는 폐자원인 포도가공부산물을 활용한 기능성 소재 개발의 기초 자료 마련을 위해, 열풍 및 동결건조한 뒤 1～20 kGy의 감마선 조사를 실시한 포도가공 부산물의 품질 특성 및 항산화활성의 변화를 관찰하였다. 색도는 열풍건조시료의 경우 3 kGy에서 가장 높은 L값과 a값을 나타낸 후 조사선량 증가에 따른 감소를 나타내었고, 동결건조시료의 경우 가장 높은 조사선량인 20 kGy에서 가장 높은 L값과 b값을 나타내어 열풍건조라는 고온의 전처리를 통한 색소의 파괴가 미리 진행되어 감마선 조사에 따른 영향을 나타내지 않았으며, 3 kGy의 감마선 조사는 열풍건조한 포도가공 부산물 시료의 색택에 좋은 영향을 미치는 것으로 나타났다. 총 페놀화합물의 함량을 측정한 결과, 열풍건조시료 메탄올 추출물에서는 3 kGy 조사구에서 가장 높은 함량을 나타내었고 조사선량 증가에 따른 감소를 나타내었으나, 비조사구보다는 조사구에서 더 높은 페놀화합물 함량을 나타냈다. 동결건조시료 메탄올추출물의 경우, 비조사구에서 가장 높은 함량을 나타내었으나 조사구에서는 3 kGy 조사구가 가장 높은 페놀화합물 함량을 나타내었다. DPPH 및 ABTS를 이용한 라디칼 소거능의 측정 결과 역시 페놀화합물 함량의 측정결과와 마찬가지로 열풍건조시료의 메탄올추출물에서 3 kGy 조사구가 가장 높은 라디칼 소거능을 나타내었다. 환원력은 시료를 1～5 ㎎/mL의 농도로 희석하여 실험하였으며, 그 결과 열풍과 동결건조시료 모두 3 kGy 조사구에서 가장 높은 활성을 나타내었다. 따라서 본 연구를 통해 3 kGy의 감마선 조사는 포도 가공 부산물의 색택 및 항산화능을 향상시킴을 알 수 있었다. 하지만 가공부산물 활용의 측면에서 볼 때, 감마선 조사에 따른 포도부산물의 항산화 활성 증가는 미약하거나 없는 것으로 나타나 큰 의미를 갖지 못했다.

The influence of the grape pomace on the ruminal parameters of sheep

To overcome an animal feed shortage in Iran, the effect of replacing alfalfa with grape ( Vitis vinifera sp.) by-product plus polyethylene glycol (PEG, MW 6000) on the ruminal parameters and retained nitrogen (Nr) of sheep was assessed. In a change-over design experiment 6 sheep with similar live weight (61.8 kg), were used during 3 periods of 28 days. The three dietary treatments, which were iso-caloric and iso-nitrogenous, were; control (alfalfa hay, barley grain, wheat chaff, wheat straw), GP diet (grape pomace, barley grain, wheat chaff and urea) and GP diet + PEG. PEG was used to deactivate tannins in grape pomace. Animals were held in individual metabolism cages. They were adapted to experimental conditions for 21 days, before the commencement of the measurement periods. In each period, the digestibilities of organic matter (OMD), NDF (NDFD), crude protein (CPD) and ruminal parameters (pH, ammonia, bacteria and protozoa population), microbial protein synthesis using urinary purine derivatives and N metabolism in sheep were measured. The concentration of OMD, NDFD and CPD was decreased using grape pomace and the addition of PEG only, improved CPD. The amount of endogenous fecal nitrogen loss and Nr in GP diet were less than control ( P < 0.05), these amounts were increased by the addition of PEG ( P < 0.05). GP diet caused reduction in ruminal parameters (pH, ammonia, cellulolytic and proteolytic bacteria population and protozoa number) and microbial protein yield as compared to the control. The addition of PEG increased those parameters ( P < 0.05). In conclusion, GP diet had a detrimental effect on the rumen parameters and Nr with positive influences of PEG addition on most of these parameters.

ANTIFUNGAL EFFECT OF ORGANIC AND CONVENTIONAL GRAPE POMACE EXTRACTS

The food and agricultural products processing industries generate substantial quantities of phenolics-rich by-products, which could be valuable natural sources of antioxidants. Grape by-products for example have been the subject of this investigation and have proven to be effective sources of phenolic compounds and other antioxidants. Extracts from grape pomace coming from organic and conventional farming practices were characterised based on total phenol content (mmol GAE g -1 extract) and antioxidant capacity (mmol Trolox equ. g -1 extract) but only minor differences between organic and conventional farming practices were found. The antifungal effect of grape pomace extracts was also tested against food-related moulds. The growth of pathogen moulds such as Penicillium crysogenum, Penicillium expansum, Aspergillus niger and Trichoderma viride was inhibited by conventional grape pomace extracts, whereas the organic extracts showed markedly lower fungostatic capacity.