Colour stability of thawed lamb chops. I. Effect of short-term frozen storage

The colour stability of thawed lamb chops was examined, by colour panel and colorimeter, under simulated retail display conditions. Chops held frozen at –20°C for 1 week had a display life of 3 days when thawed, compared with 2 days for fresh chops. When the frozen storage was increased to 8 weeks the display life was reduced to 1 day. When the whole loin was stored frozen for 8 weeks, chops cut from it and thawed had a 2-day display life. By comparison, vacuum-packed chops stored at –1.5°C for 8 weeks had a 3-day display life. The relationship between Hunter colour values and panel scores is discussed.     

Use of unripe grapes harvested during cluster thinning as a method for reducing alcohol content and pH of wine

Background and Aims: Deep red full‐bodied wines can only be obtained from grapes with complete phenolic maturity, which frequently produce wines with high pH and alcohol content. The present study focuses on a new procedure for simultaneously reducing pH and ethanol content. Methods and Results: Grapes from cluster thinning were used to produce a very acidic low‐alcohol wine. The wine was treated with high doses of charcoal and bentonite. This odourless and colourless wine was used to reduce pH and ethanol content of wine produced from grapes, which had reached complete phenolic maturity. The anthocyanin and proanthocyanidin concentrations, the mean degree of polymerisation and the monomeric composition of proanthocyanidin of reduced‐alcohol wines were similar to those of their corresponding controls. Since the pH was lower, the colour of the reduced‐alcohol wines was more intense. No significant differences were found between reduced‐alcohol wines and their controls by triangle sensory tests using dark glasses for two of the three studied cultivars. Conclusion: The procedure described allowed production of wines with reduced alcohol content and pH, while retaining similar phenolic content and sensory properties. Significance of the Study: The proposed procedure is easy to apply, does not require specific equipment and offers a means of addressing the problem of wines developing high ethanol and low pH as a result of over‐ripening of grapes.     

Extraction of phenolics from new oak casks during spirit maturation: impact on spirit colour

The increase in colour and solubilisation of extract, polyphenols and ellagitannins were studied in wine spirit in new oak casks over a period of 23 years. Ellagitannins and oak colour were solubilised during the early years of maturation. After five years, the concentration of ellagitannins decreased markedly, while colour increased, although at a lower rate. Ellagitannins were oxidised into coloured polymers and hydrolysed into ellagic acid. The dry extract, containing polysaccharides, polyphenols and lignin, increased throughout maturation, growing quickly during the early years and slowly thereafter. In a model solution, ethanol exhibits a strong solvent effect. For higher concentrations (50% v/v and more), the extraction of colour was faster, and was typically dark yellow/brown with a red tone, attributable in part to the solubilisation of lignin and lignin by-products. © 2020 The Institute of Brewing & Distilling     

Influence of the heterogeneity of grape phenolic maturity on wine composition and quality

Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest.     

Effects of ethephon, methanol, ethanol and girdling treatments on berry maturity and colour development in Cardinal table grapes

To hasten berry maturity and improve skin colour, the early-season table grape variety Cardinal was treated (post veraison) with a bunch + foliar spray using either 240 or 480 mg/L ethephon, as well as with 30% methanol, 30% ethanol (v/v); or by girdling. Treatment effects were evaluated in a randomised experimental design, with 10 replications of one plant per plot, down a single row. Ethephon at 480 mg/L applied twice, on July 2 when 5% of the berries showed colouring and on July 9 when 20% of the berries developed partial colour, increased total soluble solids, °Brix/titratable acidity and skin colour. Girdling, methanol and ethanol also increased total soluble solids and berry colouration and caused faster ripening. Ethephon at 480 mg/L was generally the most effective means of hastening ripening and improving colour.     

Original article: Prediction of the colour and polyphenolic composition of the young red wines from the phenolic potential of the grapes

The phenolic potential of the grapes of Tannat, Cabernet Sauvignon and Merlot produced in the south region of Uruguay was analysed in four years. The grapes of Tannat had the highest total phenolic richness (A280 = 80.0), total anthocyanin potential (ApH1 = 2540 mg L^?1) and extractable anthocyanin potential (ApH3.2 = 1269 mg L^?1), although there were important differences between the years. Representative winemaking of each vineyard was carried out. The differences verified in the grapes phenolic indexes were related to the colour and polyphenolic composition of the wines. The correlations between the phenolic indexes of the grapes and the colour and polyphenolic composition of the wines were very high. The estimation of the polyphenolic richness and the extractability of the anthocyanins of the grapes allow to improve the management of the winemaking and the prediction of the chromatic characteristics and the global polyphenolic composition of the wines.     

Effect of freezing grape berries and heating must samples on extraction of components and composition parameters of red wine grape varieties

Juices from grape samples subjected to two storage methods (fresh and frozen) and two post-homogenisation treatments (21^oC and 71^oC) were examined for extraction of grape berry components and compared to a microvinified wine made from the same lot of fresh grapes. Cabernet Franc ( Vitis vinifera ) and Cynthiana ( Vitis aestivalis ) grapes were evaluated in 2003. Cabernet Franc, Cabernet Sauvignon ( Vitis vinifera ), Chambourcin (interspecific hybrid) and Cynthiana grapes were evaluated in 2004. Fresh grapes from each variety were sampled, analysed and prepared for microvinification. Frozen grapes of all varieties were thawed and analysed at the same time. For all varieties in both years, heating the must of fresh or frozen grapes increased the titratable acidity (11–58%), tartaric acid levels (12–110%), potassium content (15–62%), darkness (31–97%), red colour (54–1517%) and total red pigment values (36–1171%) of juice as compared to the juice from unheated must. For all varieties in 2004, heating the must from fresh or frozen grapes increased total phenolics (43–619%) of juice as compared to the juice from unheated must. Compared to fresh grape processing, freezing the grapes and then processing at 21^oC or 71^oC had varying results (increases and decreases) regarding the extraction of components in all varieties and both years but usually provided juice with composition most similar to that of the red wine produced by microvinification. Although the degree of extraction of individual components in the juice is influenced by selection of grape storage and must processing procedures, consistency of handling and procedure provided consistent results with low variability.     

Colour changes in thermally processed cupuaçu (Theobroma grandiflorum) puree: critical times and kinetics modelling

Summary Colour changes in thermally treated cupuaçu ( Theobroma grandiflorum ) fruit puree were modelled mathematically. Isothermal experiments in the temperature range of 80–115 °C were performed and colour was measured by a tristimulus colorimeter. At each temperature total colour difference (TCD*) increased and normalized L* decreased with processing time, both following a power law model. The power of the model was temperature-dependent and described by the Arrhenius law. To estimate the model constants, a one-step non-linear regression was performed on all data. Activation energies of 31 and 36 kJ/mol were determined for TCD* and normalized L*, respectively. These results should prove useful in the design of pasteurization processes which minimize colour changes in cupuaçu puree.     

Turmeric (Curcuma longa) a natural source of edible yellow colour

Curcuma longa, L. an important natural sources of yellow colour was successfully extracted with acetone, ethanol and propanol. The liquid colour was developed from concentrated oleoresin (50 mL) by addition of 10 mL of polysorbate. The resultant liquid colour was water‐soluble. The powder colour was prepared by crystallisation of concentrated oleoresin. The best quality of crystals (dry) was formed with petroleum ether. The result of physico‐chemical properties revealed that liquid colour was soluble in all water‐based medium while crystallised colour was fat‐soluble on heating. Both liquid and crystal colour retained >80% of their colour for 6 months. It was concluded that yellow colour in liquid and crystal form could be developed from turmeric with acceptable physico‐chemical properties. Both colour can be used in food products and had good market potential.     

Spectrophotometric method for the determination of ethanol in beverages and beer samples using cerium (IV) as reagent

A simple and rapid (15min) spectrophotometric method for the determination of subpercentage ethanol in beverages is based on the colour reaction between ethanol and Ce(IV). Other alcohols and reducing substances interfere, but may be minimized by distilling the alkali and mercuric chloride treated sample. Calibration was linear up to 0.78% v/v, with r.s.d. of 5.0% at the ethanol level of 0.34% v/v. the ethanol contents of a number of non-alcoholic beverages and beer samples were determined and compared with results from AOAC and gas chromatographic methods.     

The effect of ionising radiation on the CIELAB colour co-ordinates of chicken breast meat as measured by different instruments

The colour of irradiated and unirradiated chicken breasts was measured at two laboratories (A & B). The effect of instrumental differences on the CIELAB colour co-ordinates and reflex attenuance spectra of the chicken breasts was examined. Each laboratory used two spectrophotometers, one of which was common to both. Laboratory B operated their other spectrophotometer in two different measuring geometries. Irradiated chicken breasts were found to exhibit increased a* values (greater redness) when compared with the unirradiated controls. Although differences in absolute CIELAB co-ordinates were found between instruments, all the instruments evaluated indicated increased redness and chroma values for the irradiated samples. Examination of reflex attenuance spectra indicated that the increases in a* observed were due to lesser absorption of light in the 600–700 nm region, although evidence of a change in pigment form was limited.     

Colour improvement of common carp (Cyprinus carpio) fillets by hydrogen peroxide for surimi production

The preferred colour for surimi is white, but surimi prepared from light fillets of common carp (Cyprinus carpio) is slightly pink. Hydrogen peroxide (H₂O₂; 1–3% v/v) with and without sodium tri‐polyphosphate (STP; 1–2% w/v) was added to a sodium carbonate bath (pH 7.0–11.5) resulting in a final pH range of 4.4–10.1 which was injected into carp fillets. After soaking and tumbling for 30 min at 4–10 °C, the fillets were evaluated for colour and water holding capacity (WHC). Fillets tumbled with treatment solution with different pH levels (7.0–11.5), but with no H₂O₂ or STP added, had improved colour with significantly (P < 0.05) higher L* compared with untreated fillets as the control. However, the colour improvement [(L* and colour deviation (ΔE)] was not significantly different (P > 0.05) within the pH levels (7.0–11.5) trialled. With increasing H₂O₂ levels (1–3%), fillets became lighter and ΔE increased significantly (P < 0.05), especially with a 3% H₂O₂ treatment at pH of 10.5 (adjusted pH before H₂O₂ addition, actual pH after H₂O₂ addition was 8.2). The whiteness (L*?3b*) of kamaboko produced from treated (3% H₂O₂, pH 10.5) common carp light fillets was not significantly different to that of kamaboko from Alaska pollock and threadfin bream. Treatments combining H₂O₂ (3%) with STP (1–2%) significantly reduced the L* value obtained in comparison with fillets treated with only H₂O₂ (3%). Similarly, fillets treated with STP (1%) alone, resulting in lower L* values, irrespective of treatment pH (7.0–11.5). WHC, an indicator of the quality of the fillet texture, increased from 816 g/kg at pH 7.0 without STP to 841 g/kg at pH 11.5 with 1% STP. Treatment with H₂O₂ (without STP) decreased the WHC of the fillets.     

Effect of preharvest sprays containing calcium,magnesium and titanium on the quality of peaches and nectarines at harvest and during postharvest storage

Peach and nectarine trees were foliar sprayed with a formulation containing Ca²⁺, Mg²⁺ and Ti⁴⁺. Parameters related to fruit quality were evaluated at harvest, after 7–28 days of cold storage and after subsequent ripening for 4 days at 20 °C (shelf life). At harvest, treated fruits from both cultivars had higher weight and pulp firmness than control fruits, while no effect was observed for either colour, total soluble solid content (TSS) and titratable acidity (TA) or the time required to ripen on the tree. During cold storage, lower levels of weight loss, colour evolution, TSS/TA ratio and ethylene production and higher pulp firmness were found in treated peaches and nectarines compared with control fruits. Also, the storability of treated fruits was extended for up to 14 days more than that of control fruits. During ripening at 20 °C after different periods of cold storage, parameters related to ripening evolved faster in control than in treated fruits. Also, the occurrence of the climacteric peak of ethylene production was delayed and its intensity was lower in treated peaches and nectarines than in controls. Copyright © 2004 Society of Chemical Industry     

Colour stability of thawed lamb chops. II. Chops from loins frozen for long periods

Colour stability was examined during simulated retail display of thawed chops cut from loins after frozen storage. When loins had been stored for 30 weeks at –20°C, the thawed chops had a 2-day display life. If chops were stored at –20°C for an additional 8 weeks before thawing, display life decreased to 1 day. When loins were thawed, then cut into chops, a display life of 4 days was obtained. Thawed chops from loins stored for 60 weeks behaved similarly. The experiment showed no adverse trend with increased frozen storage, except for increased drip, and indicates definite commercial possibilities for chops cut from loins stored frozen.     

Different postharvest dehydration rates affect quality characteristics and volatile compounds of Malvasia,Trebbiano and Sangiovese grapes for wine production

Experiments were carried out using an innovative technology for dehydration based on the passage of air through a tunnel. It was possible to study the postharvest behaviour, at different rates of dehydration, of Malvasia, Trebbiano and Sangiovese grapes. Malvasia and Trebbiano grapes were picked with 17.5% SSC (soluble solids content), while Sangiovese grapes were harvested fully ripe with 26% SSC. All the grapes, in different experiments, were placed in the tunnel with an air speed of 1–1.5 m s^?1, 42% RH (relative humidity) and a temperature of 21 °C. After 18 days the weight loss was 50 and 34% respectively in tunnel‐treated Malvasia and Trebbiano grapes, while it was only 13–14% in control grapes (outside the tunnel: RH around 65% and temperature about 20 °C without ventilation). The SSC rose to 35 and 27% respectively in tunnel‐treated Malvasia and Trebbiano grapes compared with 23 and 21% respectively in control grapes. In the case of Sangiovese grapes, after 7 days (the end of treatment) the weight loss was 20.5% in tunnel‐treated grapes and 10.5% in control grapes. The SSC rose to 32% and the acidity increased from 4.8 to 5.8 g l^?1 in tunnel‐treated grapes compared with 29% and 5 g l^?1 respectively in control grapes. Total phenols and anthocyanins almost doubled in tunnel‐treated Sangiovese berries. Volatile compound analysis revealed a higher ethanol concentration in all tunnel‐treated grapes but a lower concentration of ethyl acetate and acetic acid. Copyright © 2004 Society of Chemical Industry     

Effect of Colletotrichum acutatum ripe rot on the composition and sensory attributes of Cabernet Sauvignon grapes and wine

Background and Aim:  The impacts of the fungal bunch rot pathogen Colletotrichum acutatum (ripe rot) on grape growing are documented; however, little is known about how the disease affects the resulting wine. This work aimed to investigate how ripe rot affects wine composition and sensory properties.
Methods and Results:  Wine was made using Cabernet Sauvignon grapes grown in the Hastings Valley (NSW). Berries with ripe rot tended to shrivel and acquired a distinctive off flavour and bitterness, described as hessian sack and musty. Wine made from the infected fruit had a higher pH and a higher level of residual sugar, but lower titratable acidity. Volatile acidity in wine made from uninfected fruit was 0.57 g/L, but increased to 0.83 and 1.06 g/L with 1.5 and 3% infection, respectively. Wine made from infected fruit had higher levels of both glycerol and gluconic acid indicative of fungal contamination. Alcohol concentration was also higher in wine made from infected fruit. Sensory analysis indicated that wine made from as low as 3% infected fruit had a similar colour density to control fruit, but a distinctive off-flavour, and browner colour hue.
Conclusions:  As far as we are aware of, this is the first report of a correlation between the level of grape infection by C. acutatum and wine composition in Australia.
Significance of the Study:  These results underline the problems of red grapes infected with C. acutatum . It provides viticulturists and winemakers with information to be considered when assessing grape quality and winemaking process for red wines.     

Auto‐fluorescence for analysis of ripening in Thompson Seedless and colour in Crimson Seedless table grapes

Background and Aims: Ripening of table grapes is routinely followed by measurement of soluble solids, acidity, colour and firmness. Non‐destructive means to measure ripening can be of great value to determine optimal harvest time and to compare the effect of treatments on ripening. Methods and Results: The portable fluorescence detector (Multiplex III, Force A, France) generates 12 signals which are processed to ratios which compensate for the structural complexity of the cluster. Sampling was carried out in a Thompson Seedless vineyard in four blocks and over 9 weeks. The simple fluorescence ratio (SFR_R) (correlated to chlorophyll level) decreased exponentially with an R² value of 0.97, while flourscence excitation ratio (FER_RG) (correlated to anthocyanin level) displayed an increasing linear trend with an R² of 0.98. The flavonoids (FLAV) ratio which was shown to correlate to the level of flavonoids increased during the first 5 weeks of veraison and then reached a steady level. In an experiment on Crimson Seedless grapes, application of abscisic acid (ABA) resulted in a dose response using the anthocyanin (ANTH) ratio which is the log expression of FER_RG. In a further experiment on Crimson Seedless, the clusters were separated into three colour groups after veraison; ABA and Ethrel were applied, leaving untreated clusters in each colour group as control. The ANTH ratio was able to quantify a significant increase in colour for each group with respect to its control. Conclusions: The results suggest that portable fluorescence detectors may become important tools to study ripening of table grapes. Significance of the Study: This is the first report of the use of fluorescence to follow ripening of table grapes.     

Degradation kinetics of tomato juice quality parameters by ozonation

Tomato juice samples were ozonated with control variables of ozone concentration (1.6–7.8 %w/w) and treatment time (0–10 min). Effects of ozone processing variables on quality parameters of pH, ^oBrix, titratable acidity (TA), cloud value, non-enzymatic browning, colour values ( L *, a *, and b *) and ascorbic acid (AA) content were determined. No significant changes ( P  > 0.05) in pH, ^oBrix, TA, cloud value and Non enzymatic browning (NEB) ( P  ≤ 0.05) were found with ozonation. L *, a * and b * colour values were significantly affected by ozone concentration and treatment time. A significant reduction of AA (96 %) was observed at an ozone concentration of 7.8%w/w and a treatment time of 10 min. Results presented in this study indicate that visual colour and nutritional quality is significantly affected during ozone processing. Thus, the effects of ozonation on the nutritional properties of tomato juice should be considered by processors prior to its adoption as a preservation technique.     

Effect of the dry ice maceration and oak cask fermentation on colour parameters and sensorial evaluation of Tempranillo wines

The impact of dry ice maceration (DIM) and oak cask fermentation (OCF) on characteristics of Tempranillo wines elaborated in a warm climate has been studied as an alternative procedure to traditional red winemaking (CT) to obtain highly coloured wines. Oenological and colour parameters were measured to determine the influence of these techniques on wines along the winemaking process. DIM and OCF techniques were found significantly different to CT for colour intensity and percentage of blue. Moreover, both induced easily perceptible changes in CIELAB coordinates (lower L*, higher a* and values) than CT and also affect main wine's sensory attributes (e.g. increased polyphenols extraction in DIM and to a lesser extent OCF, and therefore produced wines with higher colour than CT). Although differences tend to decrease with ageing, these practices seem feasible alternatives to improve quality characteristics of young red wines from grapes grown in warm climates.