Component analysis and sensory evaluation of Korean black raspberry (Rubus coreanus Mique) wines

Three types of Korean black raspberry wines were made from juice, juice‐pulp and juice‐pulp‐seed. Changes in the physicochemical properties and key compounds of the wines during fermentation were determined. The colour intensity was weakened with a 50% decrease in the anthocyanin content, but the colour intensity was strengthened by supplementation with pulp and seeds. Citric acid was the major organic acid (approximately 90%) of the wines, and the amino acid content was lowered to less than 10% by fermentation. The total volatile compound content was increased 5.3 times and nine new compounds were identified. The major components of the wines were isobutanol, n‐propanol and isoamyl acetate. The juice‐pulp‐seed wine contained the highest contents of anthocyanin, polyphenols and proanthocyanin. The anti‐oxidative activity of wines increased with an increasing content of polyphenols. The content of proanthocyanidin, a compound for pucker and bitter tastes, was approximately two to three times greater than in commercial grape wines. In a sensory test, the highest scores for colour, flavour, taste and overall acceptance were awarded to the juice‐pulp‐seed wine.     

The effect of UV‐C in combination with H2O2 treatments on microbial response and quality parameters of fresh cut pear discs

The response of Escherichia coli ATCC 11229, Listeria innocua ATCC 33090 and Zygosaccharomyces bailii NRRL 7256 in fresh‐cut pear to simultaneous and serial combined treatments involving H₂O₂ immersion (3% w/v; pH 3.0; 25 °C; 2.0 or 5.0 min) and UV‐C exposure (7.5 min; 3.7 kJ m^?2) was investigated. For selected treatments, native flora, sensory and colour changes were also evaluated. E. coli and L. innocua were more sensitive than Z. bailii. Serial H₂O₂/UV‐C treatments were more effective than the simultaneous arrangement. The single effect of UV‐C was enhanced by the combination with 5 min H₂O₂, hence avoiding the recovery of the surviving population. The combined treatment kept optimal microbial stability and exhibited more luminosity than the single UV‐C treatment. Texture profile analysis conducted using a trained panel showed that H₂O₂/UV‐C processed pear discs were perceived with significantly less hardness and fracturability but as juicy as untreated discs. Consumers found them pleasant.     

Wine bottle closures: physical characteristics and effect on composition and sensory properties of a Semillon wine 1. Performance up to 20 months post-bottling

A Semillon wine was bottled using 14 different closures: a screw‐cap type, two grades of conventional natural cork, two ‘technical cork’ closures (natural cork with a synthetic component), and 9 closures manufactured from synthetic polymer material. Closure performance was evaluated for physical aspects (e.g. extraction force and energy, change in closure diameter, and ease of closure reinsertion), and for wine composition and sensory properties. Wine under the screw cap closure retained the greatest concentration of sulfur dioxide (SO₂) and ascorbic acid and had the slowest rate of browning. For other closures the trend of SO₂ loss relative to the screw cap closure was apparent from an early stage of testing, and was most evident in the group of synthetic closures, intermediate in the conventional corks, and least evident in the technical cork closures. The loss of SO₂ was in general highly correlated with an increase in wine browning (OD₄₂₀) and the concentration of SO₂ in the wine at six months was a strong predictor of future browning in the wine, particularly after eighteen months. Neither the concentration of dissolved oxygen at bottling (0.6–3.1 mg/L), nor the physical closure measures were predictors of future browning. For several closures upright storage tended to accelerate loss of SO₂ from the wine, but in many cases this effect was marginal. The closures differed widely in regard to physical characteristics, and in general synthetic corks appeared least ‘consumer‐friendly’ in terms of extraction forces, energies, and ease of closure re‐insertion, but there was a trend for natural cork closures to exhibit larger variability in physical characteristics than technical cork and synthetic closures. Sensory analysis indicated large differences in wine flavour properties, with closures which tended to result in the best retention of free SO₂ having wine sensory scores for ‘citrus’ that were generally high whilst scores for the attributes ‘developed’/‘oxidised’ were low. The situation was reversed for wine under closures that performed poorly in the retention of free SO₂. It was found that below a critical level of free SO₂ remaining in the wine, closures exhibited substantially higher ‘oxidised’ aroma. Whilst trichloroanisole‐type (TCA) taint was a noticeable problem for some cork and technical cork closures, any plastic‐type taint appeared not to be a problem with most synthetic closures.     

Freezing-thawing effects on the colour and texture of European catfish flesh

The freezing-thawing effect on the colour of raw fillets and on the texture of cooked fillets of European catfish ( Silurus glanis ) was studied. European catfish coming from two rearing conditions occurring in France were analysed by sensory and instrumental measurements. Fillets of European catfish became lighter, yellower and less bright after a freezing-thawing cycle. An increase in hardness and a decrease in resilience, disintegration and shear resistance were also highlighted after a freezing-thawing cycle. We could make the hypothesis that these variations of colour and texture were due either to mechanical damage or muscle protein denaturation. Fillets also became less juicy after a freezing-thawing cycle because of a loss of water-holding capacity.     

The effect of trehalose, sucrose and maltodextrin addition on physicochemical and sensory aspects of freeze - dried strawberry puree

Use of trehalose as a novel drying aid to produce freeze-dried strawberry puree was studied and compared with conventional drying aids for fruit purees, namely sucrose and maltodextrin (MD). Glass transition temperature ( T _g), colour, sensory profile and consumer preference were determined. Purees dried with MD and/or trehalose presented higher T _g values as compared to sucrose. Sensory evaluation indicated that samples dried with trehalose retained fresh strawberry aroma and flavour, keeping a good sweetness/sourness balance, while puree dried with sucrose was mostly sweet. Addition of MD caused an increase in products visual viscosity and sourness, attributes which were negatively correlated to preference. Trehalose presented several advantages for increasing the quality of freeze dried fruit purees. It raised T _g, gave an adequate sweetness/sourness balance, and allowed a better perception of fresh strawberry flavour.