Juice Color Research Articles

Quality of physalis (Physalis pubescenss L.) juice packaged in glass bottles and flexible laminated packs during storage at 5°c.

Husk tomato ( Physalis pubescens L.) is one of the important 100 species in the Physalis genus of the Solanaceae family. Among unexploited tropical fruits, Physalis is a very promising fruit. Physalis is included in the priority list of many governments' horticulture and fruit export plans. It is relatively unknown in importing markets and remains an exotic fruit. The important step toward developing Physalis as a commercial crop was maximizing its technological applications. The objective of our study was to prepare a new processed pasteurized Physalis juice and to study the effects of storage and packaging on its nutritional properties. The pulp was yellowish or orange with a yield of 64%. The fresh juice had a light sweet and acidic taste (pH 3.5). The titratable acidity was 1.43%, polyphenols 76.6mg/100mL and vitamin C 38.8mg/100mL. Physalis juice was rich in carotenoids (70μg/mL). The nutritional and bio-physical characteristics of Physalis juice packaged in glass bottles and flexible laminated packs during storage under refrigeration (5±1°C, 85-90%RH) for 6 months were studied. Carotenoids, polyphenolic substances and ascorbic acid contents were gradually reduced throughout cold storage, where this reduction was more pronounced in juice packaged in flexible laminated packs. A slight increase in total acidity was observed with cold storage prolongation, especially in juice packaged in flexible laminated packs. Significant differences in color were found between the same juice packaged either in glass bottles or in flexible laminated packs, where the juice color was darker in flexible laminated packs. It could be noticed that, there was no migration of Na ions from glass bottles to processed juice formulas during the cold storage period. In flexible laminated packs, a slight increase of Al ions throughout the cold storage period but not exceeding the safety limit of Al daily intake (3.5mg/day). It was concluded that Physalis juice packaged in glass bottles had higher storage stability than that packaged in flexible laminated packs.

Anthocyanins and color degradation in ozonated grape juice

Grape juice samples were ozonated with processing variables of ozone concentration (1.6–7.8% w/w) and treatment time (0–10 min). Effects of processing variables on grape juice color values ( L, a and b) and anthocyanins were determined. The changes in lightness ( L) values and total color difference (TCD) values were fitted well to zero-order kinetics whereas, a and b followed first-order kinetics. Three major anthocyanins were observed in the grape juice namely cyanidin-3- O-glucoside ( Cy3Gl, 133.9 mg/L), delphinidin-3- O-glucoside ( Dy3Gl, 21.4) and malvidin-3- O-glucoside ( My3Gl, 3.2 mg/L). Significant reductions in anthocyanin content were observed during ozonation. During ozonation Cy3Gl was found to be stable compared to Dy3Gl and My3Gl. Changes in Cy3Gl were fitted well to the fraction conversion model. The results presented in this study indicate that both color and anthocyanin content are significantly affected during ozone processing. Thus, the effects of ozonation on the grape juice should be considered by processors prior to its adoption as a preservation technique.

OPTIMIZATION OF HMF FORMATION IN WHITE AND RED GRAPE JUICE CONCENTRATES STORED IN VARIOUS LAMINATED FILMS USING RESPONSE SURFACE METHODOLOGY

ABSTRACT The effect of packaging materials on the formation of 5-hydroxymethyl 2-furfural (HMF) was investigated. Red and white grape juice concentrates at 70°Brix filled into pouches from three different packaging materials including polyethylene/polyamide (PE/PA), polyethyleneterephthalate/polyethylene (PET/PE) and polyethyleneterephthalate/aluminum/polyethylene (PET/Al/PE) were stored at 28 and 37C for 6 months. HMF, browning index (A420) and clarity (%T625) analyses were conducted by taking samples at 1th, 2nd, 3rd and 6th months during storage. The coefficient of determination, R2 values for HMF formation, A420 and %T625 were 1.00. Statistical analysis showed that packaging materials, grape juice concentrate, storage temperature and time were significantly (P < 0.0001) correlated to HMF, A420 and %T625. Based on response surface and contour plots, optimum conditions for HMF formation, A420 and %T625 were: (PET/A1/PE) packaging materials, storage temperature of 36.53C and storage time of 1.22 months for white grape juice concentration and (PET/A1/PE) packaging materials, storage temperature of 28.12C and storage time of 5.80 months for red grape juice concentration. PRACTICAL APPLICATIONS Results revealed that packaging materials, the colour of grape juice concentrate, storage time and temperature were significantly (P < 0.0001) correlated to HMF, browning index and clarity. Best packaging material was PET/AL/PE lamination among the ones tested. Temperature should be kept low during storage to obtain better quality. Red grape juice concentrates were wore sensitive to storage time and temperature than white ones. Increased storage temperature from 28C to 37C yielded more than ten-fold increase on average HMF content.

Microfiltration of mosambi juice using low cost ceramic membrane

This work reports on microfiltration (MF) studies of mosambi juice using low cost ceramic membrane prepared from locally available inorganic precursors. Characterization of the prepared membrane was done by SEM analysis, porosity determination and pure water permeation experiments. The average pore diameter, total porosity and hydraulic resistance of the membrane were evaluated as 0.285 μm, 23.6% and 9.26 × 10 11 m 2/m 3, respectively. Dead-end MF experiments were performed for both centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). It was observed that after MF, important properties like TSS, pH, acidity and density of both CJ and ETCJ were almost unaffected. However, significant improvement in juice colour, clarity and AIS was observed. It was also observed that the clarified juice can be stored in refrigerated condition for more than 30 days without significant change in juice quality. Different membrane pore blocking models were used to analyze the observed permeate flux decline.

Discrimination of climacteric and non‐climacteric melon fruit at harvest or at the senescence stage by quality traits

AbstractBACKGROUND: This paper characterizes the quality traits at harvest and the changes associated with fruit senescence based on fruit physiological behaviour (climacteric or non‐climacteric) found in a collection of near‐isogenic lines (NILs) of melon (Cucumis melo L.). Data from both stages of postharvest development were analyzed by univariate and multivariate statistical analysis.RESULTS: The principal components and random forest analyses of the fruit quality traits allowed the best classification of the NILs by time (harvest, senescence), or by climacteric behaviour at harvest, but not at the senescent stage. The overall quality profile of the non‐climacteric senescent melons was, in general, very different from that of the climacteric ones, and was in accord with a longer storage life. Most of the taste quality traits (individual sugars or sucrose equivalents, titratable acidity and the citric, oxalacetic, glutamic and succinic acids) and the traits related to skin, flesh and juice colour parameters (chroma, hue angle) helped to distinguish the climacteric NILs from the non‐climacteric ones independently of the time considered.CONCLUSIONS: The time had a stronger effect on quality than the physiological behaviour. The discrimination by climacteric or non‐climacteric behaviour was usually better at harvest than at the senescent stage irrespective of the methodology used. Principal component analysis was the best multivariate method to discriminate by time and physiological behaviour followed by random forest and linear discriminant analysis. Copyright © 2009 Society of Chemical Industry

Effect of 1-methylcyclopropene on the sensory, visual, and analytical quality of greenhouse tomatoes

Sensory and analytical quality parameters were measured to evaluate the effect of 1-methylcyclopropene (1-MCP) on hothouse tomatoes ( Lycopersicon esculentum Mill., cv. Rapsodie). Commercially grown tomatoes, harvested at the ‘pink’ maturity stage, were treated with 250 nL L −1 1-MCP for 8 h at 15 °C and held at 15 °C for a minimum of 5 d, prior to ripening at 22 °C for 5–8 d. This regime simulated storage conditions used by distributors, retailers, and consumers. Fruit quality parameters [color ( L, a, b), weight, soluble solids, titratable acidity [H +], pH, expressed juice and tomato color index (TCI)] were determined. Sensory analysis was conducted to evaluate perceived flavor (aroma/taste), texture and visual attributes over the ripening period. Treated and untreated fruit were compared for intensity of aroma/flavor (vegetative aroma, ripe tomato aroma, tomato flavor and sourness), texture (firmness, mealiness) and visual attributes [external color (redness, greenness), internal color (redness, greenness), gel color (redness, greenness), juice color (redness, greenness), seed size] by eight judges in duplicate, in five sensory sessions. Statistical contrasts were used to determine differences between 1-MCP treated and untreated fruit, as well as between ‘ripe’ and ‘advanced maturity’ 1-MCP fruit. The 1-MCP treated fruit differed from the control fruit in textural and visual attributes, but not in flavor attributes. Treated fruit had a reduced red color, less red gel color, smaller seed size and greater mealiness. These changes were reflected by concomitant changes in pH, L, b and TCI values. Mealiness was positively correlated ( r = 0.824, p < 0.01) with TCI for 1-MCP treated fruit, suggesting that 1-MCP influenced cell wall integrity during the delayed maturation process. However, it was unknown if this textural changes would be large enough to influence consumer acceptability of the fruit, and warrants further investigation.

Effect of ascorbic acid on deterioration of carotenoids and colour in ultrafrozen orange juice

The influence of externally added ascorbic acid (AA) on the deterioration of carotenoid pattern and colour of orange juices has been assessed. Regardless of the enrichment of the samples with ascorbic acid, the changes in their carotenoid profile were analogous and involved mainly the epoxycarotenoids. The decreases in the levels of the two major carotenoids, namely (9 Z)-violaxanthin and (9 Z)- or (9′ Z)-antheraxanthin, due to acid-elicited 5,6-epoxide to 5,8-furanoxide isomerizations, were markedly distinct, with the levels of the former dropping more markedly. It was observed, in any event, that the decreases were higher in the sample spiked with the higher amount of ascorbic. In view of these results it has been hypothesized that the location of (9 Z)-violaxanthin in orange cloud particles could be more accessible to the juice acids to that of (9 Z)- or (9′ Z)-antheraxanthin. In addition, the enrichment of the juices seems to promote the contact of the carotenoids and the acids during their deterioration. In terms of colour, it has been concluded that these changes in the carotenoids led to colour differences that can be discerned visually and that the use of a black background for the measurements yielded a better differentiation among the samples.

International Multidimensional Authenticity Specification (IMAS) Algorithm for Detection of Commercial Pomegranate Juice Adulteration

The pomegranate fruit ( Punica granatum ) has become an international high-value crop for the production of commercial pomegranate juice (PJ). The perceived consumer value of PJ is due in large part to its potential health benefits based on a significant body of medical research conducted with authentic PJ. To establish criteria for authenticating PJ, a new International Multidimensional Authenticity Specifications (IMAS) algorithm was developed through consideration of existing databases and comprehensive chemical characterization of 45 commercial juice samples from 23 different manufacturers in the United States. In addition to analysis of commercial juice samples obtained in the United States, data from other analyses of pomegranate juice and fruits including samples from Iran, Turkey, Azerbaijan, Syria, India, and China were considered in developing this protocol. There is universal agreement that the presence of a highly constant group of six anthocyanins together with punicalagins characterizes polyphenols in PJ. At a total sugar concentration of 16 degrees Brix, PJ contains characteristic sugars including mannitol at >0.3 g/100 mL. Ratios of glucose to mannitol of 4-15 and of glucose to fructose of 0.8-1.0 are also characteristic of PJ. In addition, no sucrose should be present because of isomerase activity during commercial processing. Stable isotope ratio mass spectrometry as > -25 per thousand assures that there is no added corn or cane sugar added to PJ. Sorbitol was present at <0.025 g/100 mL; maltose and tartaric acid were not detected. The presence of the amino acid proline at >25 mg/L is indicative of added grape products. Malic acid at >0.1 g/100 mL indicates adulteration with apple, pear, grape, cherry, plum, or aronia juice. Other adulteration methods include the addition of highly concentrated aronia, blueberry, or blackberry juices or natural grape pigments to poor-quality juices to imitate the color of pomegranate juice, which results in abnormal anthocyanin profiles. To adjust the astringent taste of poor-quality juice or peel extract, addition of nonpomegranate sugars is a commonly detected adulteration method. The profile generated from these analyses combined with information from existing databases and published literature has been integrated into a validated IMAS for PJ, which can be utilized to detect PJ adulteration. In this survey of commercial pomegranate juices, only 6 of 23 strictly met all of the IMAS criteria.

Mechanical Cane Pruning and Crop Adjustment Decreases Labor Costs and Maintains Fruit Quality in New York ‘Concord’ Grape Production

Four pruning techniques were evaluated from 1999 to 2003 in a commercial ‘Concord’ (Vitis labruscana) vineyard in Westfield, NY. Manual pruning, mechanical pruning with manual pruning follow-up, mechanical pruning with fruit thinning, and minimal pruning with fruit thinning averaged a 2.4-fold difference in retained nodes per vine. Treatments with crop adjustment required fruit thinning in 3 of 5 years to maintain an acceptable crop size. Manually pruned vines, mechanically pruned vines with manual follow-up pruning, and mechanically pruned vines with crop adjustment had similar yields, juice soluble solids, lignified periderm, juice color, juice titratable acidity, and juice pH in 4 of 5 years. Minimally pruned vines tended to have slightly higher yield and lower juice soluble solids, color, and titratable acidity in 3 of 5 years. Pruning system cost estimates indicated a 56% and 80% cost reduction per acre when comparing manual pruning with mechanical pruning plus manual follow-up or mechanical pruning plus mechanical fruit thinning, respectively. These results support two commercially acceptable and sustainable pruning management options for New York ‘Concord’ grape production.

Effects of pressure homogenization on particle size and the functional properties of citrus juices

Homogenization is useful in the citrus industry to improve the quality of citrus juices. The aim of this work was to study the effect of the homogenization pressures 0, 5, 10, 15, 20, 25 and 30 MPa on the particle size distribution, colour, cloudiness, and flavonoid content of fresh citrus juices to determine the ideal conditions of juices to be used in the development of functional fresh fruit. The results showed that homogenization pressure affected the particle size distribution and colour of the citrus juices, which made it possible to define different sample groups on the basis of the applied pressure. In fresh juice the contents of the flavonoids were not affected by homogenization pressure but after five months stored juice the content of the flavonoid hesperidin was affected..

Avoiding non-enzymatic browning by high-intensity pulsed electric fields in strawberry, tomato and watermelon juices

Changes in color and 5-hydroxymethyl furfural (HMF) of strawberry, tomato and watermelon juices were evaluated after high-intensity pulsed electric field (HIPEF) processing using a response surface methodology and compared to the thermally-treated and unprocessed juices. HIPEF-processed juices retained the color better, and had lower HMF concentration than those treated by heat. The influence of pulse frequency, pulse width and polarity on color difference (Δ E) and HMF content of the juices were well fitted through second-order models. In the three products, monopolar mode and frequencies below 100 Hz promoted few changes on Δ E, keeping constant the initial amount of HMF. In addition, it was feasible to minimize non-enzymatic browning by the application of pulse widths beyond 4.5 μs for strawberry juice and up to 2.5 μs for tomato and watermelon juices.

Shelf life and sensory evaluation of orange juice after exposure to thermosonication and pulsed electric fields

Thermosonication (TS) and pulsed electric fields (PEF) represent emerging technologies for liquid food preservation. In the present study shelf life and sensory attributes of orange juice were evaluated following treatment with a combination of these technologies (TS/PEF). The juice was exposed to batch TS at 55 °C for 10 min followed by continuous PEF at a field strength of 40 kV/cm for 150 μs. High-temperature short-time (HTST) pasteurisation (94 °C for 26 s) was used as a control. Sensory attributes (i.e. colour, odour, sweetness, acidity, flavour and overall acceptability) of different orange juices processed with TS/PEF or exposed to HTST pasteurisation were evaluated by 37 panellists using a hedonic scale (1–9 points). All sensory attributes were rated equivalent for TS/PEF- and HTST-treated juice ( P ≥ 0.05). During the shelf life study the effect of TS/PEF on selected physical properties (pH, °Brix and conductivity), microbiological activity and colour stability was monitored directly after processing and following 25 °C storage up to 168 days. No significant change in the physical properties was detected after TS/PEF or HTST treatment during 168 days of shelf life ( P ≥ 0.05). Although the counts for both treatments were consistently within safe levels (<1000 CFU/ml) during the 168 days of storage, overall microbial counts in TS/PEF-treated juice were higher than in thermally pasteurised juice ( P < 0.05). Colour attributes showed significant differences between TS/PEF- and HTST-pasteurised juice throughout the shelf life study ( P < 0.05). Although promising results have been obtained further optimisation is required in order to maximise the quality of the resulting product.

Anthocyanin and colour degradation in ozone treated blackberry juice

Abstract Response surface methodology (RSM) was used to investigate the effects of ozone concentration (%w/w) and treatment time (min) on the anthocyanin content and colour of fresh blackberry juice. RSM methodology based on a two factor five level central composite design was employed with control variables of ozone concentration (0 to 7.8%w/w) and treatment time (0 to 10 min) at a constant gas flow rate. Predicted models were found to be significant ( p R 2 ) of 0.89, 0.82, 0.95, 0.86 and 0.97 for L , a , b , TCD and anthocyanin content respectively. Ozone concentration and treatment time were found to be critical factors influencing both anthocyanin and colour degradation. This study demonstrated that response surface methodology can be employed to model colour and anthocyanin degradation of ozonated blackberry juice while minimising the number of experiments required. Industrial relevance In the United States (US) legislation requires fruit juice processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Consequently a number of commercial fruit juice processors in the US started to employ ozone for fruit juice pasteurisation. Ozonation was approved by the FDA in 2001 as a direct additive to food. The FDA issued industry guidelines for fruit juice processing with ozone [FDA, (2004). FDA Guidance to Industry, 2004: Recommendations to Processors of Apple Juice or Cider on the Use of Ozone for Pathogen Reduction Purposes. Available online http://www.cfsan.fda.gov/~dms/juicgu13.html .], however this report concludes that these guidelines are based upon limited scientific data. This paper investigates the effect of ozone processing on the anthocyanin content and colour of blackberry juice. The results presented demonstrate that the effect of ozonation on the nutritional properties of blackberry juice or juice products containing blackberry should be considered by processors prior to its adoption as a preservation technique.

Food safety knowledge and behaviors of women, infant, and children (WIC) program participants in the United States.

Although the incidence of foodborne illnesses has declined, thousands of cases are still reported in the United States. In conjunction with industry efforts to reduce foodborne pathogens, consumers play an important role in decreasing foodborne illnesses. To assess food safety knowledge and food handling behaviors of low-income, high-risk populations, a study was conducted with participants of the Special Supplemental Food Program for Women, Infants, and Children (WIC). A survey was conducted with 1,598 clients from 87 WIC agencies nationwide. Descriptive statistics, chi-square analyses, t tests, and analyses of variance were calculated. A majority of respondents received food safety information from WIC (78.7%), family (63.1%), and television (60.7%). Most respondents recognized the necessity for washing and sanitizing cutting boards and utensils (94.3%), but only 66.1% knew the correct ways to sanitize. Using a thermometer to ensure doneness of meat was least recognized (23.7%) and used by even fewer respondents (7.7%). The majority (77.4%) used color of meat and/or juices when checking the doneness of ground beef items. Over half of the respondents (58.4%) used acceptable thawing methods, but many thawed frozen meats on the counter (21.0%) or in a sink filled with water (20.6%). There were significant differences in thawing methods, overall knowledge scores, and overall behavior scores among different racial and ethnic groups. White respondents had higher knowledge scores than did Hispanics, and blacks had lower behavior scores than did individuals in the other racial and ethnic groups. Results of the study suggested the need for food safety education for low-income consumers and different messages to be delivered to specific demographic groups.

Some physicochemical characteristics and degradation kinetic of anthocyanin of reconstituted pomegranate juice during storage

To investigate color quality in a systematic way, it is necessary to objectively measure color, as well as pigment concentration. The variation of anthocyanins content, chromatic parameters ( L ∗, a ∗, b ∗, hue angle, chroma, and Δ E), pH, titratable acidity, and soluble solid content of reconstituted pomegranate juices were investigated at one month intervals during storage period at 4, 20, and 37 °C for 210 days. The main anthocyanins quantified by HPLC–UV were cyanidin, delphinidin, and pelargonidin, 3-glucoside, and their 3,5-diglucoside. Juice color was investigated using Hunterlab colorimeter. The anthocyanin content and chromatic parameters of pomegranate juice changed significantly with increasing storage temperature and time ( p < 0.05), and the degradation of pigments followed first-order reaction kinetics. The total anthocyanin content significantly correlated with the some chromatic parameters of the pomegranate juice. The soluble solid content and pH increased significantly during storage at all temperatures.

Carotenoid and phenolic profile of tomato juices processed by high intensity pulsed electric fields compared with conventional thermal treatments

The effect of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1500 μs of overall treatment time with bipolar pulses of 4-μs at 100 Hz) and heat pasteurisation (90 °C for 30 s or 60 s) on carotenoids and phenolic compounds as well as on some quality attributes (pH, soluble solids and colour parameters) of tomato juice was evaluated and compared, having the untreated juice as a reference. Processing enhanced some carotenoids (lycopene, β-carotene and phytofluene) and the red colour of juices, whereas no significant changes in phenolic compounds, pH and soluble solids were observed between treated and untreated juices. A slight decrease in overall health-related compounds was observed over time, with the exception of some carotenoids (β-carotene and phytoene) and caffeic acid. However, HIPEF-processed tomato juices maintained higher content of carotenoids (lycopene, neurosporene and γ-carotene) and quercetin through the storage time than thermally and untreated juices. Hence, the application of HIPEF may be appropriate to achieve not only safe but also nutritious and fresh like tomato juice.

Effect of rind pigments and juice colorants on juice claribility, settling time and mud volume of sugarcane

Sixteen sugarcane varieties varying from light to dark rind color were evaluated for various pigments viz., chlorophyll, carotenoids, xanthophylls and anthocyanins. Phenols, amino acids and reducing sugars in juice which contribute to the color of the juice and some technological juice process related parameters were also estimated. Significant differences among varieties were found for pigments, juice colorants and technological juice process related parameters. The dark colored varieties were found to contain higher amount of anthocyanins than that of light colored varieties. The variety Co 8209 had significantly higher content of amino acids in juice and may result in juice process related problems. Higher optical density (OD) values of raw juice were obtained from the varieties Co 94008, CoV 92102, Co 86032 and ISH 69 due to the presence of higher quantities of anthocyanins. The magnitude of drop in the OD values of juice after clarification was less in the varieties Co 62198 and Co 86011. Correlation studies between various pigments, juice colorants and juice process related technological parameters indicated that total carotenoids positively associated with the juice mud volume. Anthocyanins positively influenced the percent impurities in juice as indicated by lead number. Higher content of phenols in cane juice was found to increase the color of the raw juice and settling time. The findings of the present study indicated that some of the juice process related parameters like claribility, settling time and mud volume are not only influenced by the pigments from rind of the cane and colorants in juice but are independent of the sucrose content of the juice.

Effects of agricultural practices on instrumental colour, mineral content, carotenoid composition, and sensory quality of mandarin orange juice, cv. Hernandina

AbstractBACKGROUND: Frequent consumption of fruits and vegetables is associated with a lowered risk of cancer, hypertension and heart disease, due, among other factors such as modulation of gene expression and improvement of gap junctional communication, to the presence of various forms of antioxidants present in the foods as carotenoids. Otherwise, consumers demand organic products which they believe have more flavour and are of greater benefit to the environment and human health. The effects of organic farming on CIE L*a*b* colour, mineral content, carotenoid composition and sensory quality of Hernandina mandarin juices were studied.RESULTS: Organic farming of mandarin oranges resulted in juices with higher contents of minerals and carotenoids, and of better sensory quality. For instance, organic juice contained a total concentration of carotenoids of 14.4 mg L−1 compared to 10.2 mg L−1 of conventional juice.CONCLUSION: Mandarin orange juices can be considered as a good source of some important nutrients, such as potassium and antioxidant chemicals, e.g. β‐cryptoxanthin. Copyright © 2008 Society of Chemical Industry

Thermal Degradation Kinetics of Pigments and Visual Color in Watermelon Juice

Thermal degradation of total carotenoids, lycopene and visual colour of watermelon juice was studied at 50–90°C up to 5 h. Total carotenoids content in fresh watermelon juice was reduced from 4.568 to 0.929 mg/100 g, lycopene from 4.403 to 0.82 mg/100 g and Hunter ‘a × b’ value from 251.66 to 89.59 when heated at 90°C for 5 h. First order model explained the degradation behaviour of total carotenoids, lycopene and Hunter ‘a × b’ value evident from correlation coefficient (R2) higher than 0.93. The dependence of degradation rate constant of total carotenoids, lycopene and Hunter ‘a × b’ value on temperature was adequately explained by Arrhenius equation. The activation energies for total carotenoids, lycopene and Hunter ‘a × b’ value were 24.19, 26.46, and 55.47 kJ/mol, respectively. Total carotenoids and lycopene were correlated with Hunter ‘a × b’ value with R2 > 0.99 indicating that visual colour may be used to predict lycopene and total carotenoids contents in watermelon juice.

Modelling colour degradation of orange juice by ozone treatment using response surface methodology

Response surface methodology was used to investigate the main effects and interactions of ozonation on orange juice colour degradation. A Box–Behnken experimental design was employed with control variables of gas flow rate (0–0.25Lmin−1), ozone concentration (1.2–4.8%w/w) and treatment time (2–10min). Predicted models were found to be significant (p<0.001) with regression coefficients of 0.97, 0.97, 0.99, 0.99, 0.99, 0.98 for L∗, a∗, b∗, chroma, TCD, hue, respectively. Predicted values of colour parameters obtained using model equations were in good agreement with the experimental values. Gas flow rate, ozone concentration and treatment time were found to be critical factors influencing colour degradation. This study showed that Box–Behnken design and response surface methodology could be employed to model colour degradation parameters of ozonated orange juice while minimising the number of experiments required.