Micro-oxygenation and oak chip treatments of red wines: Effects on colour-related phenolics,volatile composition and sensory characteristics. Part II: Merlot wines

The character of Merlot wines after the treatments of micro-oxygenation and subsequent chips addition, as regards the colour-related phenolics, volatile composition and sensory characteristics, was studied. An increase in the degree of polymerisation of red pigments and a decrease in the value of the red component of the colour (a^*) and the degree of co-pigmentation were observed. The concentrations of monomeric anthocyanins and anthocyanin-derived pigments, such as hydroxyphenyl-pyranoanthocyanins and anthocyanin-ethyl-flavan-3-ol adducts, significantly decreased. With regard to the wine aroma, the micro-oxygenation produced a decrease of some esters, alcohols and benzenic compounds and increased some terpenes and C₁₃-norisoprenoids. With regard to sensorial analysis, micro-oxygenation treatment resulted in higher scores for the red fruit and spicy attributes and caused the presence of new attributes (nutty and sweet fruit). This technique produces a lower level of the typical oak chip aromas (vanilla and woody) in Merlot wines.     

Micro-oxygenation and oak chip treatments of red wines: Effects on colour-related phenolics,volatile composition and sensory characteristics. Part I: Petit Verdot wines

In this paper, the effects of micro-oxygenation before malolactic fermentation and oak chip treatments on Petit Verdot red wines have been evaluated. Our attention was focused on the colour characteristics, the phenolic compounds related to the colour of red wine, the volatile compounds, and the sensory characteristics of the wines. The micro-oxygenation treatment promoted the stabilisation of red wine colour by increasing the formation of colour-related phenolic compounds (higher concentrations of pyranoanthocyanins and anthocyanin-ethyl-flavan-3-ol adducts). Red wine aroma quality was improved with the addition of oak chips (eugenol and 4-vinyl-guaiacol concentration increased). Micro-oxygenation treatment resulted in higher scores for the plum/currant and spicy attributes, as well as the appearance of tobacco and nutty notes which were absent in the non-treated wines. Nevertheless, the typical oak chip aromas (vanilla and woody) were observed to a lesser extent in wines obtained by micro-oxygenation.     

Techniques for improving or replacing ageing on lees of oak aged red wines: The effects on polysaccharides and the phenolic composition

Alternative techniques to the ageing on lees are being looked for in order to guarantee the improvements provided by this technique but eliminating its disadvantages. The aim of this work was to study the effect of ageing on lees and other alternative techniques (addition of β-glucanase enzymes to the lees; use of different yeast commercial preparations with or without β-glucanase enzymes; use of non-toasted oak chips; and ageing on lees together with micro-oxygenation) on the phenolic compounds, colour, proteins, polysaccharides and sensorial characteristics of red wines during vinification and ageing in oak barrels for 6 months on two consecutive vintages.     

葡萄酒中溶解氧与酚类物质的研究进展

微量溶解氧对葡萄酒的成熟起着十分重要的作用。简要介绍了葡萄酒中主要酚类物质——单宁和花色素苷。着重论述了在微量溶解氧条件下。单宁和花色素苷向更稳定色素转化的三种基本途径，以及葡萄酒中酚类物质的变化对葡萄酒品质的影响。最后。展望了溶解氧在葡萄酒熟化过程中的应用前景以及应注意的问题。     

微氧技术在葡萄酒陈酿中的应用

重点研究了微氧处理对葡萄酒酒精度、残糖、干浸出物、总酸、挥发酸、色度,色调的影响,结果表明,适宜的微氧处理对酒精度、残糖、干浸出物、总酸无显著影响,不会增加葡萄酒中挥发酸的含量,可增加葡萄酒的色度,使420 nm的吸光值增加,使游离态花色素苷向结合态转化,促进葡萄酒颜色的稳定。     

微氧技术在葡萄酒酿造中的应用

文章主要介绍微氧技术应用的设备和一般原则,及微氧处理对于葡萄酒颜色、口感和理化指标的影响,并展望微氧技术在葡萄酒酿造中的应用前景及应注意的问题.     

Colour and image texture analysis in classification of commercial potato chips

The images of commercial potato chips were evaluated for various colour and textural features to characterize and classify the appearance and to model the quality preferences of a group of consumers. Features derived from the image texture contained better information than colour features to discriminate both the quality categories of chips and consumers’ preferences. Entropy of a¹ and V and energy of b¹ from images of the total chip surface, average and variance of H and correlation of V from the images of spots and/or defects (if they are present), and average of L¹ from clean images (chips free of spots and/or defects) showed the best correspondence with the four proposed appearance quality groups (A: ‘pale chips’, B: ‘slightly dark chips’, C: ‘chips with brown spots’, and D: ‘chips with natural defects’), giving classification rates of 95.8% for training data and 90% for validation data when linear discriminant analysis (LDA) was used as a selection criterion. The inclusion of independent colour and textural features from images of brown spots and/or defects and their clean regions of chips improved the resolution of the classification model and in particular to predict ‘chips with natural defects’. Consumers’ preferences showed that in spite of the ‘moderate’ agreement among raters (Kappa-value = 0.51), textural features have potential to model consumer behaviour in the respect of visual preferences of potato chips. A stepwise logistic regression model was able to explain 86.2% of the preferences variability when classified into acceptable and non-acceptable chips.     

Effects of processing conditions on the quality of vacuum fried apple chips

The effects of pretreatment and processing conditions on the quality of vacuum fried apple chips were studied. As blanched apple slices were pretreated by immersing in fructose solution and freezing prior to vacuum frying, more uniform porosity was observed on the surface (or cross-section) of apple chips as examined by scanning electron microscopy (SEM). During vacuum frying, the moisture content and breaking force of apple chips decreased with increasing frying temperature and time while the oil content increased. The L values of fried apple chips decreased apparently with increasing frying temperature. However, when apple slices were fried at 100°C for up to 20 min, both a and b values increased rapidly. Statistical analysis with the central composite rotatable design showed that the moisture content, oil content, color, and breaking force of apple chips were significantly (P⩽0.05) correlated with concentration of immersing sugar solution, frying temperature and frying time. Based on surface responses and contour plots, optimum conditions were: vacuum frying temperature of 100–110°C, vacuum frying time of 20–25 min, and immersing fructose concentration of 30–40%.     

Augmented release of Teretrius nigrescens Lewis (Coleoptera: Histeridae) for the control of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in stored cassava chips

A trial was set up in northern Benin to evaluate the potential of Teretrius nigrescens to reduce the infestation and damage to cassava chips caused by storage insects. Cassava chips were stored for 5 months in mud silos and 50 adults of T. nigrescens were added when the stores were first filled. Stores where no predator was released were monitored as controls. The main storage insects observed were Prostephanus truncatus and Dinoderus spp. Initial chip weight varied between 102 and 246 g with no difference between treatments. Chip weight and number of holes on chips initially differed between treatments after 2 months of storage. After 3 months of storage, losses reached 40-50% without T. nigrescens and 30-40% when cassava chips were stored with T. nigrescens. A farmer can increase his profit by 1437 Fcfa/100 kg (1$=560 Fcfa, 1£=968 Fcfa; 1€=656 Fcfa, as on 2 December 2005) through the use of T. nigrescens because losses are reduced by 11%. Data analysis showed that there were significant differences (P<0.0001) between the two treatments for the number of holes, number of insects, weight of each chip as well as damage. There were twice as many P. truncatus and holes on chips in stores where T. nigrescens was not released. The addition of the predator to farmers’ stores is an economic option for controlling losses due to insects in cassava chips.     

Characterization of microwave vacuum-dried durian chips

Durian CV. Monthong was subjected to microwave vacuum drying (at 13.33 kPa) to produce durian chips. Various levels of microwave power (3.88 W g⁻¹, 5.49 W g⁻¹ and 7.23 W g⁻¹) were used. Prior to the microwave vacuum drying, the sliced durian was either chilled at 4 °C or frozen at −18 °C. Both pretreatments yielded non-significant difference in dissipation factor (p > 0.05). Among several thin layer models, the Page model was found to be the best for explaining the drying characteristics of durian chips. An increase in the microwave power intensity produced a clear increase in the drying rate and did not affect lightness and yellowness of the durian chips (p > 0.05). The structure and hardness of the dried durian chips were comparable to that of conventionally fried durian chips. In addition, microwave vacuum drying reduced the fat content of the durian chips by at least 90%, compared with conventionally deep fried durian chips.     

微氧处理技术在葡萄酒陈酿中的应用

微氧处理技术是指以专用的微氧处理装置,向葡萄酒中有控制地通入微量的氧气,也可以辅助使用橡木片或橡木替代品,从而优化葡萄酒的陈酿条件,达到提高葡萄酒质量的目的。此项技术可以有效地稳定葡萄酒的颜色,改善口感,提高葡萄酒的感官质量。本文研究了微氧处理技术对干红葡萄酒陈酿的作用,找出了适当的处理条件。该项技术可以部分替代橡木桶陈酿,显著缩短陈酿周期,大大降低葡萄酒陈酿成本,提高企业生产能力和经济效益。     

Use of natural antioxidants in refined palm olein during repeated deep-fat frying

An optimization study on the use of oleoresin rosemary extract, sage extract and citric acid added into refined, bleached and deodorized (RBD) palm olein before deep-fat frying of potato chips was performed using a constrained mixture design. Results revealed that the use of these natural antioxidants could improve the sensory acceptability of potato chips during a 5-day repeated deep-fat frying. All three antioxidants significantly (P<0.05) improved the sensory characteristics, including appearance, taste, crispiness, odor and overall acceptability. After day 5 of frying, the most acceptable fried potato chips were those fried in oil containing a combination of 0.059% oleoresin rosemary extract, 0.063% sage extract and 0.028% citric acid. The natural antioxidants significantly (P<0.05) lowered the rate of oxidation of oil during deep-fat frying and contributed to measured sensory acceptability of fried potato chips.     

Milling and particle size of cowpea flour and snack chip quality

Texture and color attributes were determined for snack chips made from cowpea flour. Chips were prepared from flour milled through 0.5, 1.0, and 2.0 mm screens; in addition, the ratio of cowpea flour to cornstarch was varied. Snapping force was slightly higher for chips made from fine flour. In general, the ratio of total energy to peak force (E/PkF) determined by the Kramer shear test increased with more finely milled flour, or addition of starch. Color values (L*, a*, and b*) indicated that chips with greater cowpea protein/cornstarch ratios were darker and browner. Discriminant function analysis was used to relate instrumental measurements to consumer hedonic scores. Of particular importance was the (E/PkF) ratio from the Kramer shear test. Chips with lower E/PkF values had higher acceptability scores. In turn, the E/PkF values were related to the extractable starch content. The apparent starch content was dependent on either the amount of starch added, or by the milling conditions. In general, chips produced from finely milled flours had greater apparent starch content than those produced from coarsely milled flours.     

A review on micro-oxygenation of red wines: Claims,benefits and the underlying chemistry

Micro-oxygenation is the process of deliberately introducing minute, measured amounts of oxygen into wines, with the aim of bringing about desirable changes in colour, aroma and texture. It involves the use of specialised equipment to regulate the doses of oxygen that are administered. The main claims concerning the effect of micro-oxygenation in wines include an improvement in the health of yeasts during alcoholic fermentation, better wine colour and stability, more complex organoleptic characteristics, a reduction in sulphur off-odours and, also, the ability to mimic the reactions that occur during wine oak-ageing. In this paper we review the different claims and the chemistry that underlies these claims and discuss the most important factors that should be taken into account when applying micro-oxygenation and the most recent innovations.     

Performance of a lipase-catalyzed transesterified palm kernel olein and palm stearin blend in frying banana chips

The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-fat frying media at 180°C for banana chips for seven consecutive days. The samples were then analysed for iodine value (IV), free fatty acid (FFA) content, peroxide value (PV), thiobarbituric acid (TBA) value, p-anisidine value (AV), total polar compounds (TPC), fatty acid composition, specific extinction, E^1%_1cm at 233 and 269 nm, polymer contents, viscosity and colour indices. The fried banana chips were analysed for acceptability by sensory evaluations. Storage properties of the banana chips were also evaluated by trained sensory panellists and a modified TBA test. The transesterified blend was found to have significantly (P<0.05) higher IV, FFA, PV, TBA value, AV, TPC, E^1%_1cm at 233 and 269 nm values, polymer content, viscosity and colour indices compared to the control, indicating that the transesterified blend was more susceptible to oxidative deterioration during deep-fat frying. CS generally showed the largest changes in most of the parameters, basically due to its high polyunsaturated fatty acid levels. There was no significant difference (P>0.05; for all the attributes tested) between the acceptability of the banana chips fried by the transesterified and control blends. However, the banana chips fried in CS had significantly (P<0.05) lower scores in terms of flavour, aftertaste and overall acceptability. This might be due to the typical hydrogenation flavour of CS. In the storage stability study of the banana chips, it was found that the banana chips fried in the transesterified blend were significantly (P<0.05) more rancid (lower score in sensory evaluations) and had a higher TBA value at the end of the storage time than the control.     

Response Surface Methodology Study for Optimization of Effects of Fiber Level, Frying Temperature, and Frying Time on Some Physicochemical, Textural, and Sensory Properties of Wheat Chips Enriched with Apple Fiber

In this study, wheat chips enriched with apple fiber were produced, and response surface methodology was used for the determination of the simultaneous effects of processing variables selected as fiber level (0–15 %), frying temperature (160–180 °C), and frying time (40–60 s) on some physicochemical, textural, and sensorial properties of chips. Ridge analysis was conducted to determine the optimum levels of processing variables. Predictive regression equations with high coefficient of determination (R ²?≥?0.728) were constructed. Addition of apple fiber increased the dry matter; ash content; L, a, and b values of samples, while increase of frying temperature caused decrease of the hardness values. Overall acceptability of chips enriched with apple fiber decreased with the increase of frying temperature, but wheat chips enriched with apple fiber and fried at low temperatures received highest sensory score. Ridge analysis showed that maximum taste score would be attained at fiber level?=?15 %, frying temperature?=?170 °C and frying time?=?40 s.     

Physical,Sensorial and Chemical Characteristics of Simulated Chips of Cassava (Manihot Esculenta Crantz): Rice (Oryza Sativa L.) Mix

Cassava-rice ratio and cooking time-temperature combinations in baked and fried simulated chips making enriched with carrot, celery, curry leaves and skim milk were studied using completely randomized design. Research found that interaction between mix formula and cooking methods was significantly affected (p<0.05) the physical, sensorial and chemical characteristic of the simulated chips. The best baked simulated cassava-rice simulated chips was resulted from 80:20 ratio, baked at 140 °C for 14 minutes, and the fried cassava-rice simulated chips with 60:40 ratio fried at 150 °C for 2.5 minutes. The fried chips have finer microstructure and more preferable than the baked one. However, both best chips were potential to be further developed.