Ochratoxin A in grape pekmez (grape molasses) consumed in Turkey

In this study, ochratoxin A (OTA) in 55 home-made, 20 commercial and 7 organic grape pekmez (grape molasses) produced in Turkey was investigated. OTA was detected in 73% of home-made pekmez samples, in 35% of commercial pekmez samples and in 71% of organic pekmez samples. Eleven per cent of the samples had OTA levels higher than 10 µg/l. The highest OTA level (31 µg/l) was detected in organic pekmez. The maximum OTA levels were 15 µg/l and 12 µg/l in home-made and commercial pekmez samples, respectively. Mean OTA levels were 3.5 µg/l, 1.4 µg/l and 9.2 µg/l in home-made, commercial and organic pekmez samples, respectively. Organic pekmez samples and home-made pekmez samples had higher OTA contamination than commercial pekmez samples. Results confirm OTA contamination in grape pekmez samples, indicating that the OTA level in grape pekmez could be a potential risk for consumers.     

Some properties of yoghurt produced by adding mulberry pekmez (concentrated juice)

Fruit-flavoured yoghurt was made by adding 2.5, 5.0, 7.5 and 10.0% mulberry pekmez (MP) into milk. The effects of the MP on the quality and fermentation process of the yoghurt were determined. The titratable acidity, pH, viscosity, whey separation and lactic acid bacteria (LAB) counts were determined at weekly intervals for 28 days. The pH range of the MP yoghurts was 4.65–5.57 and the pH of the plain yoghurt was 4.47 ( P  < 0.05). The addition of MP led to an increase in the fermentation time and a decrease in the viscosity of the yoghurts. Statistically significant differences were found between the plain and MP yoghurts in terms of pH (4.01 and 4.35), viscosity (5429 and 3175 cP) and number of LAB (7.07 and 6.48 log cfu). During storage, the titratable acidity, viscosity and LAB counts of MP yoghurts were lower and the whey separations higher than those of controls.     

Development and characterization of black mulberry (Morus nigra) pekmez (molasses) composite films based on alginate and pectin

Production of composite films is an important approach to improve functionality of edible films, by combining different polysaccharides, proteins, and lipids. Carbohydrate-based composite films are most attractive, which have good film-forming ability due to their unique colloidal properties. Fruit purees include high polysaccharide content that plays a role to have desirable film properties including mechanical resistance, efficient barrier properties, and selective permeability against oxygen transmission. The purpose of this study was to characterize physical, barrier, mechanical, thermal, and water sorption properties of composite films formulated with different mulberry pekmez concentrations (26, 32, and 38 °Brix) based on alginate or pectin. All film-forming solutions were showed shear thinning behavior with higher yield stress and viscosity-shear rate data were fitted to Ostwald de Waele model (R² ≥ 0.943). A noticeable decrease in tensile strength of films with increasing concentration was determined, but films prepared with high concentration showed more flexible. The mechanical properties of pectin films exhibited weakened properties compared to alginate films. Increasing pekmez concentration in the film matrix improved the water vapor permeability of alginate films, whereas pectin films showed reverse behavior as resulting in cracks and crack propagation within the structure. The sorption isotherms of films showed a typical profile of foods contain high soluble components and the Guggenheim–Anderson–deBoer (GAB) model gave a good fit for all of the obtained data. The results showed that mulberry pekmez films based alginate have a potential for food applications depends on the physical properties and for the replacement of non-biodegradable plastic packaging.     

缓释保鲜纸对无核白葡萄采后贮藏品质的影响

为延长葡萄的保鲜时间,以无核白葡萄为试验材料,在果实包装中放入8种缓释保鲜纸进行处理(CT1～CT8),以空白组(CK)和2种市售葡萄保鲜纸组别(市售Ⅰ、市售Ⅱ)为对照,在温度为(0±1)℃、相对湿度为80%的条件下贮藏55 d,测定样品的腐烂率、落粒率、果梗褐变指数、pH值、质量损失率、可滴定酸含量及可溶性固形物含量、硬度及SO₂残留量。结果表明,与空白组及市售Ⅰ、市售Ⅱ组别相比,贮藏55 d时,CT3处理组无核白葡萄果实腐烂率、落粒率与果梗褐变指数最低,分别为11.47%、10.78%、10.43%;该组别无核白葡萄pH值、质量损失率、可滴定酸及可溶性固形物含量、硬度均较优,分别为3.38、0.20%、0.85 g/L、14.0%、3.87 N;该组别SO₂残留量最低(34.5 mg/kg)。     

新疆红提葡萄贮藏期冰点研究

以新疆红提葡萄为实验材料,研究冰点及其与可溶性固形物含量(SSC)和pH等的相关性,为红提葡萄安全低温保鲜提供理论依据。结果表明:红提葡萄冰点温度与SSC呈极显著负相关,但是,随着贮藏期延长,多糖、双糖、蛋白质等降解为小分子可溶性物质,或果实含水量降低,即使SSC相同,贮藏后期冰点也低于前期;冰点与pH呈显著负相关,含水量越大,冰点越高。     

巨峰葡萄低温贮藏过程中主要多糖降解酶活性变化的研究

果蔬细胞壁酶活性与果实的种类和贮藏品质密切相关。本实验以巨峰葡萄为原料,研究不同冷藏温度（0℃和4℃）下与葡萄浆果软化相关的多种酶类:果胶酯酶（PE）、葡聚糖内切酶（EGase）、果胶内切酶（endo-PG）和果胶外切酶（exo-PG）活性的变化规律。结果表明,冰温可以较好地抑制细胞壁酶活性,延长贮藏期。较低的贮藏温度对PE的影响不大,0℃贮藏延缓了EGase活性峰值出现的时间,有效的降低了endo-PG和exo-PG活性。总体来看,EGase、endo-PG和exo-PG活性的变化对葡萄贮藏过程中质地变化及腐烂起到了更为重要的作用。      

Antioxidant activity and dietary fibre of Prensal Blanc white grape (Vitis vinifera) by‐products

Stem and pomace of a white grape (Vitis vinifera) variety, Prensal Blanc, were studied for the first time: general composition and dietary fibre components together with the total soluble polyphenol content and antioxidant activity. Both by‐products present high contents of total dietary fibre (TDF), 790 g kg^?1 d.m. (stem) and 716 g kg^?1 d.m. (pomace). Values of the soluble dietary fibres in relation to TDF differed: 5% (stem) and 14.4% (pomace). Similar values of Klason lignin were found: 229 g kg^?1 (stem) and 278 g kg^?1 (pomace), however, the pomace exhibited more than twice the content of the condensed tannins (168 g kg^?1) with regard to the stem (79 g kg^?1). Notable were the high resistant protein contents of both by‐products. Stem and pomace showed appreciable amounts of total soluble polyphenols (87 g kg^?1 against 35 g kg^?1 respectively). The free radical scavenging capacity of the former by‐products was determined using the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) method, obtaining EC₅₀ values of 0.79 g d.m. g^?1 DPPH (stem) and 1.32 g d.m. g^?1 DPPH (pomace). These data shows that both vinification by‐products from the Prensal Blanc variety are a good source of dietary fibre and have antioxidant properties.     

Impact of edible coatings and packaging on quality of white asparagus (Asparagus officinalis, L.) during cold storage

The effects of edible coatings and plastic packaging on quality aspects of refrigerated white asparagus spears were studied using two different experimental protocols. The first included four coating formulations based on carboxymethyl-cellulose and sucrose fatty acid esters, whey protein isolate alone and in combination with stearic acid, and pullulan and sucrose fatty acid esters, and an uncoated sample serving as a control. The second set consisted of four treatments; uncoated asparagus spears (control), coated with a carboxymethyl-cellulose formulation, packaged in plastic packaging and combination of coated and packaged asparagus spears. All products were stored at 4 °C and the quality parameters such as weight loss, texture, visual appearance, lignin and anthocyanins concentration, and colour were evaluated during their storage. Edible coatings exhibited a beneficial impact on the quality of asparagus by retarding moisture loss, reducing hardening in their basal part and slowing down the purple colour development. The plastic packaging had a remarkable influence in reducing weight loss and retarding hardening but its impact to the rest of the quality parameters was similar to that of the edible coatings. The combination of packaging and edible coating did not seem to offer any additional advantage on asparagus spears apart from the fact that the product had a brighter appearance at the middle part of the stem compared to the packaged spears alone.     

Antioxidant protection of white grape pomace on restructured fish products during frozen storage

White grape antioxidant dietary fibre (WGDF) was obtained from white grape (Vitis vinifera, var. Airén) pomace from wine production. The antioxidant capacity of WGDF was determined in minced fish muscle (MFM) during frozen storage. Concentrations of 0, 2, and 4% WGDF ((0-WGDF), (2-WGDF), and (4-WGDF) respectively) were added to MFM samples. Analyses were carried out immediately after preparation of samples and over 6 months of storage at −20 °C. WGDF was characterized in terms of dietary fibre (DF) (insoluble and soluble), total polyphenols and antioxidant capacity, and multifunctional antioxidant assays were done on all the MFM samples. The addition of white grape DF considerably delayed lipid oxidation in minced horse mackerel muscle during the frozen storage. Vacuum-packing the sample with 2% WGDF significantly enhanced the antioxidant properties of WGDF.     

酿酒葡萄皮渣经贮存和红外干燥后的质量变化比较

本文研究了酿酒葡萄皮渣在未经干燥下的贮存过程中及其经红外干燥处理后的质量变化,一方面对其在存放过程中的质量变化进行分析,另一方面探究红外干燥处理酿酒葡萄皮渣的可能性。处理方式为将收集到的葡萄皮渣分别贮存0、1、3、5和7d后晒干,贮存1d的皮渣分别进行葡萄皮和葡萄籽超微粉碎处理,其余的只进行葡萄籽超微粉碎处理;取适量贮存1d的皮渣进行红外干燥并分别进行葡萄皮和葡萄籽超微粉碎处理。通过对超微粉的微生物(酵母菌、霉菌和细菌)、单体酚(8种)和真菌毒素(展青霉毒毒素和赭曲霉毒素)的含量变化进行检测分析,发现随着贮存时间的延长,酵母菌含量先升高后降低,霉菌和细菌以及真菌毒素含量均显著升高,各单体酚含量则显著降低;贮存1d后进行红外干燥处理的超微粉的微生物含量明显降低,说明红外干燥具有很好的灭菌效果,各单体酚有一定损失,而真菌毒素含量没有明显变化。综合考虑,酿酒葡萄皮渣收集后应立即进行干燥处理,红外干燥可以用于酿酒葡萄皮渣的干燥处理。      

Evolution of anthocyanins during maturation of tempranillo grape variety (Vitis vinifera) using polynomial regression models

In general, the anthocyanin content of grapes increases during ripening but presents a concentration minimum a few days before physiological maturity. This minimum is sharper for the acyl derivatives. Significant behavioural differences were found between monoglucosides and their acyl derivatives. A polynomial model was used to describe the evolution of anthocyanins in the maturation of Tempranillo grapes (Vitis vinifera L).     

采前纳他霉素处理对玫瑰香葡萄货架期品质及生理的影响

以玫瑰香葡萄为试材,采用不同浓度的纳他霉素进行采前浸果处理,研究常温(25℃)货架期内葡萄的贮藏品质及生理的变化。结果表明,质量浓度为0.5g/L的纳他霉素可以抑制采后葡萄果粒和果梗的霉烂,显著降低失重率,提高好果率,保持葡萄果实硬度,维持其低水平的呼吸强度,延长葡萄贮藏寿命,提高葡萄贮藏品质和安全性。     

山东酿酒葡萄发展技术层面需要实现两个突破

葡萄酒产业发展的基础是葡萄基地建设,而葡萄基地建设的技术前提是对园区风土条件与具体葡萄品种生物特性的了解、掌握。具体地区的风土条件包括：地形、地貌、地质、土壤、光照、气温、降雨等,是葡萄生产的环境要素。     

巨峰葡萄采后常温贮藏水分与质构变化关系的研究

以巨峰葡萄为原料,利用全质构分析(TPA)研究常温(15、30℃)贮藏时葡萄水分含量与质构特性变化的关系。结果表明:葡萄贮藏温度越高水分含量下降越快,且贮藏前期和贮藏末期水分含量下降速度较快。随着贮藏时间的延长,葡萄浆果硬度、胶黏性、弹性、凝聚性、咀嚼性均明显下降。15℃贮藏时,葡萄水分含量与硬度、凝聚性、弹性、胶黏性及黏附性极相关(p<0.01),尤其是硬度及弹性,相关性系数为0.866和0.888。30℃贮藏时水分含量与硬度、弹性显著正相关(p<0.01),与凝聚性显著负相关(p<0.01),但与咀嚼性和胶黏性的相关性并不显著。      

Effect of storage on the phenolic content,volatile composition and colour of white wines from the varieties Zalema and Colombard

Different quality attributes and chemical components of wines change during storage as a function of a series of factors. Thus, in young white wines, changes in phenolics, that lead to modifications of their colour as a result of oxidation processes, are well-known. These reactions can also alter their volatile profile giving rise to the appearance of new aromas, which in some cases are undesirable. In this study we have carried out a thorough evaluation of the changes in the colour, volatiles and phenolics of Zalema and Colombard wines during 1 year of storage under different conditions of temperature and position. The phenolics and colour were more affected than was the volatiles profile and wines kept in the cold could be clearly distinguished from the others, whilst the position of the bottles onlt slightly affected the wines during storage. Results showed that the blending of Zalema wines with Colombard wines may be an appropriate means of enhancing the acidity of the former without dramatically affecting its character.     

Comparative analysis of flavonoids in white and red table grape cultivars during ripening by widely targeted metabolome and transcript levels

The flavonoid metabolites were compared between red ‘Summer Black’ (SB) and white ‘Shine Muscat’ (SM) table grapes during fruit development based on widely targeted metabolome. A total of 134 flavonoids were identified in two cultivars, including 37 flavones, 33 flavonols, and 11 anthocyanidins, and so on. From young to veraison, the composition and the content of most flavonoids were decreasing in both cultivars but increased at maturation in SB. In general, SB has higher flavonoid compositions and content than SM during the whole fruit development, especially the content of anthocyanin after veraison. While the SM had higher content of flavonols such as quercetin, kaempferol and their derivatives. The expression of anthocyanin-related genes such as UFGT, OMT, GST, MATE, MYBA1, and MYBA2 was remarkably higher in SB than those in SM, which may attribute to higher anthocyanin content, while the higher expression of F3H and FLS resulted higher level of flavonols in SM. These results improve our understanding of flavonoid profiles and molecular mechanism in table grape cultivars.     

Changes in phenolic composition and antioxidant activity of white wine during bottle storage: Accelerated browning test versus bottle storage

Polyphenol content, antioxidant activity, reducing power, colour and changes during storage over nine months in bottles and after accelerated browning were studied in selected Hellenic varietal white wines. The following phenolic compounds were identified in the wines: Caftaric, coutaric, fertaric, ferulic, caffeic, p-coumaric and gallic acids, (+)-catechin and (−)-epicatechin. The results showed that the contents of most of the phenols diminished with time, with the exception of caffeic, ferulic and p-coumaric acids. Antioxidant activity increased with storage whereas reducing power remained significantly unaffected. Accelerated browning did not significantly alter the concentrations of tartaric acid esters but it increased the concentrations of the hydroxycinnamic and gallic acids. (+)-Catechin concentration was not affected while (−)-epicatechin decreased. Antioxidant activity did not show any significant change but reducing power was reduced after the end of the browning test. As for the absorbance at 420 nm, it remained unchanged during storage, but it was significantly increased after accelerated browning.     

Modelling the evolution of oxidative browning during storage of white wines: effects of packaging and closures

Shelf life of products is a key parameter for any company at local and international level that wish to improve their competitiveness; thus, there is a need to search for methods that allow one to predict the shelf life of bottled wines. In this view, the progress of chemical oxidative reactions of six Italian white wines during storage (10 months after bottling), in different packaging, was monitored by means of selected oenological parameters. The optical density at 420 nm, an index of browning, showed a progressive increase that fitted the zero‐order kinetic rate. The onset of wine browning was further tested by means of accelerated ageing in controlled temperature conditions which results, modelled using the rate constants approach, showed an Arrhenius‐like dependence from temperature, allowing to estimate apparent activation energies of oxidative chemical browning (range: 46.8–88.3 kJ mol^?1). Kinetic and thermodynamic approach provided a useful tool to predict quality changes of white wines during storage with respect to packaging conditions.     

Influences of potassium ferrocyanide on lipid oxidation of salted cod (Gadus morhua) during processing, storage and rehydration

The effects of added potassium ferrocyanide (CN) in different concentrations (2.5 ppm, 7.5 ppm and 100 ppm), in salt, on lipid oxidation in cod during salting, storage and rehydration were examined in this study. An increase in CN concentration accelerated lipid oxidation of the salted cod, as observed by increases in lipid hydroperoxides (PV) and thiobarbituric acid-reactive substances (TBARS), as well as in the development of fluorescence compounds (δF_or and δF_aq). A yellow discolouration (higher b^∗ value) of salted cod was associated with higher levels of oxidation derivatives. High correlation between PV, TBARS and free fatty acid (FFA), as well as between FFA and δF_or, was found. The results of principal component analysis showed that TBARS, b^∗ value and δF_or were the strongest indicators of lipid oxidation during salting and storage.