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.     

Formulation of Corn Zein Chewing Gum and Evaluation of Sensory Properties by the Time-Intensity Method

This study was conducted to determine the feasibility of using corn zein as a natural gum base to be an alternative to the currently used synthetic gum base. The objectives were to (1) develop a corn zein chewing gum and (2) evaluate the taste, texture, and aroma qualities compared with synthetic gum base using a time‐intensity (T‐I) method. Four corn zein gum samples, each made with a different plasticizer (oleic acid, glycerin, propylene glycol, and 1 without any plasticizer), were included in the study along with 2 synthetic gum‐base samples. Nine panelists participated in the T‐I study. Thirteen attributes were evaluated. Maximum intensity, time to maximum intensity, and duration were parameters extracted from the T‐I curve. The synthetic gum‐base samples were rated higher for the maximum intensity of sweet taste and cinnamon aroma‐by‐mouth and lower for the maximum intensity of bitter taste. The propylene glycol corn zein sample was rated the highest for cinnamon aroma and the lowest for stale, rancid, and cheesy aromas. Out of the corn zein gums, the oleic acid sample was rated the lowest for the maximum intensity of hardness. It was also rated highest for the maximum intensity of bitter taste and the lowest for sweet taste. This study showed that it is feasible to use corn zein as a gum base, but future work is needed to develop an acceptable product for consumers.     

The mozzarella cheese flavour profile: a comparison between judge panel analysis and proton transfer reaction mass spectrometry

Described in this paper is a comparison of results obtained in flavour profiling with two different approaches: classical sensory analysis and a novel instrumental technique. The mozzarella cheese flavour profile of seven different brands has been described by a sensory panel of eight judges. The same brands have been studied by means of proton transfer reaction mass spectrometry (PTR‐MS), a novel technique well suited for detecting volatile organic compounds (VOCs) down to the pptv level in air, without any need for sample concentration or trapping. The PTR mass spectra of the headspace of mozzarella samples held at 36 °C have been compared with the judge panel flavour profile. Multivariate statistical data analysis shows that the two methods perform comparable sample discrimination. Even though several questions are still open (definition of better instrumental parameters, improvements in sampling set‐up, spectral interpretation), the PTR‐MS technique appears to be a very promising method for the instrumental evaluation of the flavour sensory profile of food. This opens up new opportunities both in the control of quality and technological processes as well in the fundamental comprehension of the physiological processes of aroma perception. © 2000 Society of Chemical Industry     

Prediction of sensory quality of strawberry jam by means of sensory quality attributes of fresh fruits

Sensory analysis was performed on fresh fruits, frozen non‐cooked jam and traditionally cooked jam of 14 strawberry cultivars. The purpose was to characterise and compare the sensory quality of different strawberry cultivars and different types of jam. The results of the investigation were presented by means of multivariate modelling methods such as principal component analysis (PCA) and partial least squares regression (PLS). The sensory profile of cooked jam differed from that of fresh fruits and frozen jam, explaining 75% of the total variation in the first component. Cooked jam scored high for sweet taste, stickiness, bitter taste, earthy flavour, off‐flavour and total intensity of taste. Frozen jam had many of the same sensory characteristics as fresh fruits and scored high for strawberry flavour, fruity flavour and whiteness, while fresh fruits scored highest for colour strength, hue and sour taste. As analysed by means of PLS, sensory colour and flavour variables of fresh fruits were able to predict 35% of sensory cooked jam variables. Analysing early cultivars alone, sensory fresh fruit variables were able to predict 69% of sensory cooked jam variables. © 2000 Society of Chemical Industry