Dietary supplementation with dried olive pomace in dairy cows modifies the composition of fatty acids and the aromatic profile in milk and related cheese

This study aimed to evaluate the effect of dietary integration of dried olive pomace (DOP), a by-product of olive oil separation, on nutritional and aromatic properties of milk and cheese. Twenty dairy cows were divided into 2 groups that were balanced for milk yield, parity, and days in milk. The control group was fed a conventional diet (20 kg of dry matter/head per day), whereas the experimental group (EG) received the conventional diet supplemented with DOP as 10% of dry matter. During the trial, milk yield was recorded and the samples of milk, cheese, total mixed rations, and DOP were collected and analyzed to determine the chemical–nutritional composition and aromatic profile. Atherogenic and thrombogenic indices were calculated on the basis of the fatty acid (FA) profile of milk and cheese. Data were analyzed according to the mixed model for milk yield and chemical composition, including cows nested within treatment as a random effect, whereas the general linear model was used for the analysis of cheese parameters. Differences were assessed by Tukey's test. The EG diet had a lower content of palmitic, stearic, and linoleic acids and a higher level of oleic acid compared with the control. Dietary DOP integration did not affect milk yield and composition with the exception of protein content, which was greater in EG and significantly affected by diet and period. Instead, period was found to be significant for fat and casein in both groups. Dietary supplementation with DOP modified the FA profile of milk and cheese. There was a decrease in short- and medium-chain FA, but significance was achieved only for palmitic acid. The stearic, isomer trans of oleic (in particular vaccenic acid), oleic, and isomer trans of linoleic acids significantly increased. Monounsaturated FA increased in EG milk and cheese and saturated FA were significantly lower, whereas no difference was marked between the groups regarding level of polyunsaturated FA. Supplementation with DOP reduced atherogenic and thrombogenic indices and increased conjugated linoleic acid in both milk and cheese. The free fatty acids, ketones, lactones, esters, and phenylalanine catabolites were increased in raw milk, whereas only leucine metabolism was affected by diet in pasteurized milk cheese at both 1 and 30 d of ripening. The present results pointed out that DOP supplementation may improve the nutritional and nutraceutical properties and modify the aroma of milk and derived cheese.     

Chemical affinities between the major volatile compounds present in a grape pomace distillate

BACKGROUND: The distillation of vinification by‐products to obtain alcoholic drinks is potentially an important source of income for the producing countries and avoids the environmental problem of waste management. Traditional technologies of distillation involve an important cost in terms of time and staff. Nowadays, companies install new distillation equipment, with high capacity and equipped with rectification columns, which is an important advance. Nevertheless, few studieshave been published concerning their correct management. In this study, the major volatile compounds were determined by gas chromatography in 61 samples of grape pomace distillate, corresponding to the fractions collected during seven complete distillation cycles. RESULTS: With a high degree of significance, the concentrations of 1,1‐diethoxyethane, propanol, hexanoate and ethyl acetate present positive correlations with the ethanol. However, those of benzyl alcohol, 2‐phenylethanol, furfurol, lactate, ethyl mirystate and diethyl succinate, were negative, which indicates that both groups of compounds were vented in the fractions of major or minor alcoholic degree, respectively. In addition, knowledge of the relationships between the volatile compounds contributes to improved management of an industrial distillation unit. CONCLUSION: The correlations established between the concentrations of the different volatile compounds indicate their physico‐chemical affinities or their biochemical origin. Copyright © 2009 Society of Chemical Industry     

葡萄渣多酚的分布、生物活性及其在食品中的 应用研究进展

许多水果在加工过程中会产生大量的副产物,如葡萄酒酿造过程中产生的葡萄果渣(grape pomace,GP),由于其中含有丰富的生物活性物质,如多酚、膳食纤维、有机酸和不饱和脂肪酸等,已成为医药、化妆品和食品工业提取植物活性物质的廉价来源。尤其是酚类化合物受到越来越多的关注,葡萄渣中的酚类化合物是一类次生代谢产物,主要包括类黄酮、花青素和白藜芦醇等,很多研究已经证实这些酚类化合物具有抗氧化、抗菌、抗病毒、抗炎和抗癌等生物活性,因此,如何从葡萄渣中提取多酚化合物并将其开发成功能性食品配料,成为越来越多的企业和学者的关注。在此本文对GP多酚的组成分布、生物活性、在食品中的稳定性及其应用等进行了较全面的总结,旨在为葡萄渣多酚功能性食品的开发提供参考。     

Zinc supplementation of Friesian cows: Effect on chemical-nutritional composition and aromatic profile of dairy products

Zinc represents an essential microelement for several biochemical mechanisms. The body's inability to store zinc necessarily requires a constant dietary supply to avoid alteration of physiological functions. The aim of the present study was to investigate the effect of dietary enrichment with zinc on chemical-nutritional and aromatic properties of milk and cheese. Thirty commercial dairy cows, balanced for parity, milk production, and days in milk, were randomly assigned to 2 groups. The control group was fed with a conventional complete diet (22 kg of dry matter/animal per day), whereas the experimental group received a daily zinc supplementation of 60 mg per kg of dry complete feed. During the experimental period, the milk yield was monitored and samples of milk and caciotta cheese were collected to obtain information about the chemical-nutritional composition and aromatic profile. Dietary zinc integration did not influence milk yield and composition, but induced a marked reduction of somatic cell count and improved the oxidative stability of ripened caciotta cheese. In both milk and cheese, the experimental group samples were characterized by a lower concentration of saturated fatty acids and an increase in oleic acid, vaccenic acid, and rumenic acid. The aromatic profile of dairy products was also positively affected by dietary zinc intake, with an increase in concentration of carboxylic acids, aldehydes, and esters. The present results suggest a positive role of zinc in improving animal health and nutraceutical properties of milk and corresponding cheese. Taking into account the analysis of volatile compounds, zinc dietary supplementation of dairy cows should contribute to the production of cheeses with interesting organoleptic properties, although more studies are necessary to confirm the consumer acceptability of these changes.     

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

BACKGROUND: 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. RESULTS: 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. CONCLUSION: WGP might be utilised for the novel formulation of biscuits as an alternative source of dietary fibre and phenols. Copyright © 2012 Society of Chemical Industry     

葡萄皮渣多酚提取及其对五种食源性致病菌的抑制作用

以葡萄皮渣为原料,采用乙醇溶液对葡萄皮渣中的多酚类物质进行浸提,用Folin-Ciocalteu法测定多酚含量,通过单因素及正交试验得出浸提的最佳工艺条件为：乙醇体积分数45%,浸提温度48 ℃,浸提时间8 h,料液比1∶15(g∶mL),多酚得率为：16.48 mg/g。采用滤纸片法进行葡萄皮渣多酚的抑菌试验,发现其对金黄色葡萄球菌(Staphylococcus aureus)、志贺氏菌(Shigella)、单增李斯特菌(Listeria monocytogenes)、沙门氏菌(Salmonella)、大肠杆菌(Escherichia coli)都有一定的抑菌作用,其中对金黄色葡萄球菌和沙门氏菌的抑制效果最好。     

压榨对酿酒葡萄皮渣酚类物质提取及抗氧化活性的影响

酿酒葡萄皮渣（皮和籽）生物活性物质含量丰富,具有很高的再加工利用价值。对鲜葡萄皮渣进行压榨处理后再干燥,研究压榨对皮渣的酚类物质提取及抗氧化活性的影响。结果表明：压榨处理可以快速降低葡萄皮渣水分含量,缩短干燥时间、提高可溶性膳食纤维提取率。压榨葡萄皮总酚、原花青素的提取量均有所增加,其含量分别为19.56 mg/g和22.64 mg/g。压榨葡萄皮的抗氧化能力高于未压榨葡萄皮,其DPPH、ABTS及羟自由基清除率分别为62.90%、70.18%和41.09%,铁氰化钾还原能力及金属离子螯合能力分别为0.23%和21.33%。压榨籽和皮籽混合物的酚类物质和抗氧化活性则明显降低。抗氧化活性与总酚、原花青素存在显著的相关关系（P＜0.01）。     

Comparison of fining red wines with purified grape pomace versus commercial fining agents: effect on wine chromatic characteristics and phenolic content

The large quantity of grape pomace (seeds, skin, and peduncle) produced during the winemaking process can be a problem and the search for procedures which could permit their valorisation is considered an important issue. This study investigates the use of purified grape pomace as a fining agent for reducing the level of some wine phenolic compounds, especially tannins. For this, purified grape pomace was applied to three young red wines of different phenolic composition and the results were compared with the effect of some common commercial fining agents. The results demonstrated that grape pomace can be used to decrease the wine tannin content with similar results to those obtained with casein, while also reducing anthocyanin content although to a similar extent to when bentonite is used. The effect of purified Monastrell grapes pomace is similar in the three different studied wines although it affected the most to wines with high monomeric anthocyanin content.     

酿酒葡萄皮渣中白藜芦醇的提取及抗氧化、抗肿瘤活性研究

为了提高酿酒葡萄皮渣的综合利用价值,开发白藜芦醇新产品,对酿酒葡萄皮渣中白藜芦醇提取工艺进行研究。通过纤维素 酶水解和乙酸乙酯萃取法提取自酿葡萄酒皮渣中的白藜芦醇,利用响应面分析法优化白藜芦醇提取的工艺条件并测定了白藜芦醇的 抗氧化活性及对3种癌细胞（Hela、A549、PC-3）的生长抑制作用。 结果表明,最佳提取工艺条件为酶添加量70 U/μL、体积分数95%乙 醇与葡萄皮渣液固比20∶1（mL∶g）、酶解时间150 min、酶解温度40 ℃,在此优化条件下,提取得到白藜芦醇的提取率为144.13 μg/g; 抗氧化试验结果表明,白藜芦醇具有清除自由基的能力,当样品质量浓度为1.2 mg/mL时,对DPPH和超氧阴离子自由基的清除率分 别为（65.12±3.88）%和（54.13±3.11）%;体外抗肿瘤活性显示,其对Hela、A549和PC-3细胞的生长均具有抑制作用,半抑制浓度（IC50） 值分别为128.29 μmol/L、108.35 μmol/L和25.31 μmol/L。     

Composition,proteolysis, and volatile profile of Strachitunt cheese

Strachitunt, a blue-veined Italian cheese, received the Protected Designation of Origin (PDO) label in 2014. Its unique technological feature is represented by the dual-curd method of production. Strachitunt is produced from raw bovine milk with or without the inoculation of natural starter cultures of lactic acid bacteria, and the addition of secondary cultures of mold spores is not permitted by the product specification. Physico-chemical properties, proteolysis, and volatile profile of Strachitunt were investigated in 10 cheese samples (ripened for 75 d) made throughout spring 2015 and provided by the main cheese maker. Overall, composition parameters showed a large variability among samples. Cheese was characterized by an acid paste (pH 5.46) and a lower extent of proteolysis compared with other blue-veined varieties. The main chemical groups of volatile organic compounds were alcohols and esters, whereas ketones represented only a minor component. The erratic adventitious contamination by mold spores of the cheese milk, the unique dual-curd method of cheese-making, and the large time variability between the piercing time and the end of ripening could be highlighted as the main causes of both the distinctive analytical fingerprint and the scarce standardization of this blue-veined cheese.     

Short communication: Chemical-sensory and volatile compound characterization of ricotta forte,a traditional fermented whey cheese

Ricotta forte is a traditional whey cheese, obtained through natural fermentation of fresh ricotta, that is getting increasing attention by food traders. In view of possible initiatives for its valorization, the chemical and sensory characteristics were investigated. Samples were obtained from 14 different manufacturer, and were subjected to chemical, biochemical, volatile organic compound, and sensory analyses. All samples presented low pH with high moisture (62–66%) and fat content (57–60% on dry matter). From a biochemical point of view, the electrophoretic patterns evidenced that β-lactoglobulin was the main protein present at all sample ages. Only intermediate levels of proteolysis (20.69% ripening index) took place during aging, whereas the main biochemical event in this dairy product was lipolysis (2.10 mEq/g of acid degree value). Accordingly, free fatty acids dominated the volatile organic compound profile and strongly influenced the sensory characteristics with flavor described as rancid, pungent, acrid, and smelly feet: all associated with short-chain fatty acids such as acetic, propionic, butyric, and caproic. Finally, the sample age did not influence chemical composition, whereas it had significant effect on lipolysis and flavor intensity.     

Wine grape pomace as antioxidant dietary fibre for enhancing nutritional value and improving storability of yogurt and salad dressing

Wine grape pomace (WGP) as a source of antioxidant dietary fibre (ADF) was fortified in yogurt (Y), Italian (I) and Thousand Island (T) salad dressings. During the 3 weeks of storage at 4 °C, viscosity and pH of WGP-Y increased and decreased, respectively, but syneresis and lactic acid percentage of WGP-Y and pH of WGP-I and WGP-T were stable. Adding WGP resulted in 35–65% reduction of peroxide values in all samples. Dried whole pomace powder (WP) fortified products had dietary fibre content of 0.94–3.6% (w/w product), mainly insoluble fractions. Total phenolic content and DPPH radical scavenging activity were 958–1340 mg GAE/kg product and 710–936 mg AAE/kg product, respectively. The highest ADF was obtained in 3% WP-Y, 1% WP-I and 2% WP-T, while 1% WP-Y, 0.5% WP-I and 1% WP-T were mostly liked by consumers based on the sensory study. Study demonstrated that WGP may be used as a functional food ingredient for promoting human health and extending shelf-life of food products.     

Functional components of grape pomace: their composition,biological properties and potential applications

The roles of functional foods on human health have been realised by more and more researchers, food producers and consumers. Functional food ingredients from both plant and animal sources such as dietary fibre, soy protein isolate, whey protein isolate and omega 3 fatty acid have been widely used in functional food product development. Many fruit processing by‐products such as grape, apple and orange peels are rich in bioactive phytochemicals, dietary fibre and unsaturated fatty acids, hence have potential to serve as functional food ingredients. In this review, we summarise recent advancement of research in grape pomace (GP), the residual of grapes after wine making. The polyphenol profile of GP and their biological, antioxidant and antimicrobial activities, the stability of GP polyphenols in food system, the interaction between GP polyphenol and other food ingredients, as well as the functionalities of grape seed oil and GP fibre are covered.     

Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins

The skins of two white wine grape pomace (WWGP) and three red wine grape pomace (RWGP) from US Pacific Northwest were analyzed for their dietary fiber (DF) and phenolic composition. DF was measured by gravimetric–enzymatic method with sugar profiling by HPLC–ELSD. Insoluble DF composed of Klason lignin (7.9–36.1% DM), neutral sugars (4.9–14.6% DM), and uronic acid (3.6–8.5% DM) weighed more than 95.5% of total DF in all five WGP varieties. WWGP was significantly lower in DF (17.3–28.0% DM) than those of RWGP (51.1–56.3%), but extremely higher in soluble sugar (55.8–77.5% DM vs. 1.3–1.7% DM) (p < 0.05). Soluble polyphenols were extracted by acidified 70% acetone and measured spectrophotometrically. Compared with WWGP, RWGP had higher values in total phenolic content (21.4–26.7 mg GAE/g DM vs. 11.6–15.8 mg GAE/g DM) and DPPH radical scavenging activity (32.2–40.2 mg AAE/g DM vs. 20.5–25.6 mg AAE/g DM) (p < 0.05). The total flavanol and proanthocyanidin contents were ranged from 31.0 to 61.2 mg CE/g DM and 8.0 to 24.1 mg/g DM, respectively for the five WGP varieties. This study demonstrated that the skins of WGP can be ideal sources of DF rich in bioactive compounds.     

Short communication: Production of cottage cheese fortified with vitamin D

The availability of alternative food products fortified with vitamin D could help decrease the percentage of the population with vitamin D deficiency. The objective of this study was to fortify cheese with vitamin D. Cottage cheese was selected because its manufacture allows for the addition of vitamin D after the draining step without any loss of the vitamin in whey. Cream containing vitamin D (145 IU/g of cream) was mixed with the fresh cheese curds, resulting in a final concentration of 51 IU/g of cheese. Unfortified cottage cheese was used as a control. As expected, the cottage cheese was fortified without any loss of vitamin D in the cheese whey. The vitamin D added to cream was not affected by homogenization or pasteurization treatments. In cottage cheese, the vitamin D concentration remained stable during 3 weeks of storage at 4°C. Compared with the control cheese, the cheese fortified with vitamin D showed no effects of fortification on cheese characteristics or sensory properties. Cottage cheese could be a new source of vitamin D or an alternative to fortified drinking milk.     

Short communication: comparison of covered and uncovered Schreiber test for cheese meltability evaluation

Schreiber meltability tests were performed on glass Petri dishes, with and without the Petri dish cover placed over the cheese samples, at 100, 150, and 232 degrees C. Meltability of different process cheese and Cheddar cheese samples was determined based on the melt spread distance and area. At the test temperature of 232 degrees C, the covered Schreiber was significantly superior to the uncovered test because of no crust formation, no browning, and a circular melting pattern, which were attributed to the barrier effect of covering the cheese samples (which inhibits moisture loss during the test). The covered Schreiber test data were statistically more robust as measured by the lower average coefficient of variation than the data from the traditional uncovered Schreiber test.