Kinetic Study on Color Changes in Milk Due to Heat

Analysis of changes in terms of color difference (ΔE) and yellowness index (YI) permits evaluation of severity of heat treatment of milk. Both ΔE and YI increased at constant temperature following zero-order kinetics, at temperatures between 90 and 130°C for 1 to 60 min. Activation energy, according to the Arrhenius equation, was 101.8 and 117.5 KJ/mol for ΔE and YI, respectively. Comparison of instrumental and sensory data showed a minimum ΔE of 3.8 would be attained before visual perception of milk browning. Color values, such as ΔE or YI, are proposed as the simplest and most reproducible indices of commercial milk quality.     

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.     

Gibberellic Acid and CO2 Additive Effect in Retarding Postharvest Senescence of Parsley

We studied the effect of CO₂ and gibberellic acid (GA₃) on postharvest senescence of parsley ( Petroselinum crispum Mill.) and on ethylene induced senescence. GA₃ or CO₂ treatment retarded, with a similar efficiency, chlorophyll and protein degradation, amino acids accumulation and respiration rate. Treatment with GA₃ and CO² together resulted in an additive senescence retarding effect. The promoting effect of ethylene on senescence could be retarded with either CO₂ or GA₃. Thus, GA₃ and CO₂ could provide an effective means for maintaining fresh produce quality in parsley.     

DETERMINATION OF GERMINATION PERCENTAGE AND GERMINATION INDEX—COLLABORATIVE TRIAL AND RUGGEDNESS TESTING

A method for the determination of Germination Percentage and Germination Index in malting barley has been tested by the EBC Analysis Committee and approved for inclusion in Analytica-EBC. In the collaborative trial three pairs of barley samples with high, medium and low vigour were analysed by 16 laboratories. The r₉₅ values for the Germination Percentage ranged from 0.5% to 6.3% and the R95 values ranged from 0.5% to 8.7% increasing with lower level of mean germination percentage. The r₉₅ values for the Germination Index ranged from 0.29 to 0.74 and the R95 values ranged from 0.97 to 1.20. The ruggedness testing of the Germination Index shows that the factor temperature has a minor, but significant effect on the result, the factors time for the first count together with the volume of water, have major significant effects. The tested factors have no significant effect on Germination Percentage.