Effect of thermal pasteurization and concentration on carotenoid composition of Brazilian Valencia orange juice

Changes in carotenoid pigment content of Brazilian Valencia orange juices due to thermal pasteurization and concentration were studied. Total carotenoid pigment content loss was not significant after thermal pasteurization and concentration. However, thermal effects on carotenoid pigment contents, especially violaxanthin and lutein, were clearly observed and significant (P < 0.05). Pasteurization reduced the content of violaxanthin by 38% and lutein by 20%. The concentration process resulted in loss of lutein (17%). With the loss of lutein, β-cryptoxanthin became the major carotenoid in the pasteurized and concentrated juices. The provitamin A content of the juice (β-carotene, -carotene and β-cryptoxanthin) and the amount of zeaxanthin, which are considered to be active against age-related macular degeneration and cataracts, did not significantly decrease after pasteurization and concentration.     

Color and carotenoid profile of Spanish Valencia late ultrafrozen orange juices

Twelve ultafrozen orange juices obtained from the variety Valencia late were analysed to characterize the color and the carotenoid profile of this recently developed product. Reflectance color measurements were carried out by spectroradiometry, using a white and a black background. In order to study the carotenoid pigments occurring in the orange juice, HPLC with gradient elution with methanol (MeOH), methyl tert-butyl ether (MTBE) and water as mobile phase was used. Separations were performed on a C₃₀ column. Identification of carotenoids was made by comparison of their spectral and chromatographic characteristics with those corresponding to standards when possible. To help identify the peaks in the chromatograms, aliquots of orange juice extracts were analysed before and after treatment with hydrochloric acid (HCl) and sodium borohydride (NaBH₄), to check the presence of 5,6-epoxy-carotenoids on one hand, and, on the other hand, ketocarotenoids or carotenals.     

Effect of increased acidity on the carotenoid pattern and colour of orange juice

The colour of orange juices is one of the main factors related to their acceptability. Their colour is mainly due to carotenoids, with the particularity that the major ones, the epoxycarotenoids, can isomerise into differently coloured isomers in the presence of acid. Since acidity is one of the main characteristics of citrus, we have carried out a simple experiment to ascertain whether large changes in this parameter can affect significantly their colour. We observed that the addition of citric acid to increase the acidity of the control by roughly 50% speeded up the isomerisations initially, although it did not lead to markedly appreciable colour changes at the end of the study. These observations may be important from a food safety point of view and in relation to the consumers’ choices. In this regard, these preliminary findings could be important for food technologists and the citrus industry in general.     

Identification and quantification of soluble sugars in green beans by HPLC

An HPLC method has been performed and validated for soluble sugar analysis in green bean samples (Phaseolus vulgaris cv. Perona), with good linearity, accuracy and precision. Monosaccharides (fructose and glucose), disaccharide (sucrose) and the polyalcohol (myo-inositol) were identified in green beans samples, as well as two unknown compounds, whose content was less than 16% of total soluble sugars. Enzymatic assays using !-glucosidases were performed in order to clarify the identity of one of the components of this fraction (identified as myo-inositol). In all the batches of green beans analysed, fructose was the major sugar (0.88-1.44%), while sucrose (0.10-0.39%) and myo-inositol (0.08-0.66%) presented higher variability on the analysed samples.     

Changes in orange juice color by addition of mandarin juice

The most natural way of improving the color of orange juices is by adding other juices, which provide a more intense coloration. The US legislation allows the addition of up to 10% of mandarin juice to the orange juice to improve its color. The first objective of this study was to compare the color characteristics of juices from 11 mandarin cultivars, currently being grown in Spain. Experimental results proved that only the green-red coordinate, a*, of the orange juices can be improved by adding mandarin juice. The mandarin cultivar that provided a juice with the highest values of a* was Clemenules. Once this selection was made, the effects of adding mandarin juice at different ratios, up to 10%, on the color characteristics of the orange juice were studied. Values of the a* coordinate went from 5.50 for the pure orange juice up to 6.29 for the mixture of 90% orange juice plus 10% of mandarin juice. Finally, hedonic tests proved that regular juice consumers preferred the color of mandarin juice to that of orange juice and that they liked better the color of the juice mixture containing 10% mandarin juice than that containing 3% mandarin juice.     

基于柑橘汁多甲氧基黄酮特征成分鉴别橙汁中宽皮桔汁

榨取甜橙和宽皮柑橘各20多个品种的果汁,离心后所得上清液和果肉沉淀分别采用C18固相萃取和乙腈提取其中的多甲氧基黄酮(polymethoxyflavoned,PMFs),合并后利用高效液相色谱-二极管阵列-荧光检测串联法(high-performance liquid chromatography-diode array detection-fluorescence detection,HPLC-DAD-FLD)做定性和定量分析。以8种PMFs为变量,通过主成分分析,建立了两类果汁的鉴别模型,开发了一种经济便利的鉴别甜橙汁中是否过量掺入宽皮柑橘汁的方法。该模型对橙汁(长叶香橙汁)中掺入的宽皮柑橘汁(椪柑汁)的最低检出体积分数为10%。该方法达到国际通行标准中对橙汁中其他柑橘果汁最大添加量的检出要求,对鉴别甜橙汁纯度具有良好的效果和实际应用价值。     

Identification and quantification of S-allyl-l-cysteine in heated garlic juice by HPLC with ultraviolet and mass spectrometry detection

This paper presents a new high performance liquid chromatography (HPLC) method for the identification and quantification of S-allyl-l-cysteine (SAC), which is the most important bioactive compound present in heated garlic juice (HGJ). This method uses LC combined with an ultraviolet (LC–UV) and mass spectrometry detection (LC–MS/MS) method and is based on the dansyl chloride derivatization step. The method validation included selectivity, linearity, precision, accuracy, and sensitivity. The linear correlation coefficients (r) were always greater than 0.998. Intra- and inter-day precision for SAC at three concentrations demonstrated a relative standard deviation (RSD) of less than 15.3% for both UV and MS methods. The limit of quantification (LOQ) was 0.71 μg/g and 0.07 μg/g for UV and MS methods, respectively. The results were not significantly different between the SAC contents determined by the UV and MS detection in real HGJ samples. Both methods are proposed as useful quality control tools for accurate determination of SAC content of garlic preparations.     

Application of whole genome amplification and quantitative PCR for detection and quantification of spoilage yeasts in orange juice

Small cell numbers in complex food matrices and undefined PCR inhibitors often limit detection and identification of DNA species by molecular techniques. Thus in many industrial situations enrichment growths are performed. However, growth speed of different species in complex microbial mixtures in defined media is in most cases different, thus final results do not always reflect the starting situation. We tested DNA-strand displacement whole genome amplification as a possible substitute of enrichment growth. Using whole genome amplification on orange juice contaminated with Saccharomyces cerevisiae, we lowered detection level from 10(6) down to 10(2) cfu/ml. Whole genome amplification showed to be linear (R=0.992) and the relative yeast DNA copy number compared to other DNA templates did not change thus allowing quantitative estimation of initial contamination by quantitative PCR. Using melting point analysis, we were able to distinguish between the PCR products of the 5.8S-ITS region, obtained with universal primers from pure cultures of S. cerevisiae and Hanseniaspora uvarum, two major spoilage yeasts in orange juice and forming part of wine microbiota during fermentation. However, in mixed-contaminated samples, identification of both species was hampered by preferential appearance of the melting peak coinciding with H. uvarum, except when S. cerevisiae was the dominating species. Application of whole genome amplification did not prevent the preferential detection of H. uvarum. This handicap was resolved by applying an enrichment procedure up to saturation after which the melting peak of both species could clearly be identified.     

Volatiles of orange juice and orange wines using spontaneous and inoculated fermentations

The effect of spontaneous fermentation and inoculated fermentation on the volatile compounds of orange wine was studied. The differences on volatile compounds of orange juice and orange wine were also observed. The volatile compounds were analyzed by sensory and instrumental analysis. Solid phase microextraction was used for extraction of volatile compounds. Sensory analysis indicated that no significant differences existed on the wine odor between the two methods. A total of 17 and 19 volatile compounds were identified and quantified in spontaneous and inoculated fermentations, respectively. Esters followed by alcohols and terpenes were the most abundant volatile compounds in the two orange wines. Thirteen of these compounds were present both in the two methods. Totally 31 volatile compounds were found in orange juice, and terpenes were quantitatively the dominant group. Esters were found to be the important volatile compounds formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate, etc.     

Detection of orange juice adulteration by tangelo juice using multivariate analysis of polymethoxylated flavones and carotenoids

Reverse phase HPLC has been applied to quantify levels of polymethoxylated flavones and carotenoids in orange and tangelo juices. Lower levels of sinensetin and tetramethyl‐o‐scutellarein and higher levels of heptamethoxyflavone and tangeretin relative to nobiletin indicated the addition of tangelo to orange juice. β‐Cryptoxanthin and its esters, identified by positive ion electrospray mass spectrometry, were present in larger amounts relative to β‐carotene in tangelo than in orange juice. Using canonical discriminant analysis, the addition of 100 g kg^?1 tangelo to orange juice can be detected. © 2002 Society of Chemical Industry     

橙汁酶解增香工艺研究

采用Kramer感官评定法研究了橙汁酶解增香调控的最佳条件,结果表明:采用糖苷酶酶解橙汁具有明显的增香效果;橙汁酶解最佳反应条件为:酶解温度40℃、酶解时间80min、加酶量20u/L。     

顶空气相色谱法测定橙汁类饮料中的苯含量

苯对人的神经和心血管系统有明显的毒性,对造血机能有抑制作用。本文研究了用顶空气相色谱法测定橙汁饮料中苯的含量。将样品置于顶空瓶中,用空气(空气与液体样品的比值为15/10)进行萃取,取1mL顶空气用于气相色谱检测。结果发现,同时含有苯甲酸钠和Vc的饮料样品中有苯的存在(3.4571×10-3mg/L);当取样量为1mL时,方法检测限为0.002mg/L,相对标准差为3.8%～5.4%,回收率79.6%～90.6%,变异系数为1.02%～9.67%。     

气相色谱法快速测定柑桔汁中残留杀扑磷

报道了一种气相色谱快速测定柑桔汁中残留杀扑磷的分析方法。样品以乙腈提取,经石英毛细管气相色谱柱DB-1701分离,GC-FPD检测,外标法定量。该方法的加标回收率为99.7%～115.2%,相对标准偏差为4.3%～6.8%,按25.0mL取样量计算,方法的最低检出限为0.01mg/L。     

Quantitative determination of carbohydrates in orange juice by gas chromatography

 A gas chromatographic method using a capillary column is described for the quantitative analysis of fructose, glucose, sucrose and myo-inositol in orange juice. The method is evaluated for precision and recovery using phenyl-β-glucoside as an internal standard. The results support the suitability of the method. Carbohydrates (fructose, glucose, sucrose and myo-inositol) were determined in different kinds of orange juice. The determination of carbohydrate composition and ratios of the carbohydrate constituents provide a method to assess orange juice quality, especially the myo-inositol content and myo-inositol/fructose ratio. These new indices, which were found to be lower in samples made from concentrates, provide information on the quality and genuineness of orange juice. Received: 10 June 1997     

Quantitative determination of carbohydrates in orange juice by gas chromatography

 A gas chromatographic method using a capillary column is described for the quantitative analysis of fructose, glucose, sucrose and myo-inositol in orange juice. The method is evaluated for precision and recovery using phenyl-β-glucoside as an internal standard. The results support the suitability of the method. Carbohydrates (fructose, glucose, sucrose and myo-inositol) were determined in different kinds of orange juice. The determination of carbohydrate composition and ratios of the carbohydrate constituents provide a method to assess orange juice quality, especially the myo-inositol content and myo-inositol/fructose ratio. These new indices, which were found to be lower in samples made from concentrates, provide information on the quality and genuineness of orange juice. Received: 10 June 1997     

Profile and levels of bioactive amines in orange juice and orange soft drink

The levels of bioactive amines, pH, soluble solids, acidity, specific gravity, and total sugars were determined in different brands of orange products. Nine amines were detected in orange juice at mean total levels of 53.5 mg l⁻¹. There were significant differences, among orange juice brands, in the levels of spermidine, synephrine, spermine, octopamine, pH and total acidity. Five amines were detected in soft drinks with mean total levels of 3.85 mg l⁻¹. There were significant differences, among orange soft drink brands, in the levels of most amines and the physicochemical characteristics. The predominant amine was putrescine, followed by synephrine and spermidine, in both orange juices and soft drinks. The levels of these amines in the soft drink varied from 5.0% to 7.6% of the mean levels in orange juice, suggesting that less than 10% of orange juice could have been used in the soft drink.     

Identification and quantification of phenolics in aromatic bitter and cherry liqueur by HPLC with electrochemical detection

An HPLC-based method with electrochemical detection was optimized for quantitative analysis of phenolic compounds in an aromatic bitter and a cherry liqueur, which are different types of alcoholic beverages with a high phenolic content. The method requires only filtering of samples prior to the HPLC analysis and is recommended for routine analysis. Two slightly different gradients were needed for the analysis of the two beverages. Eleven and eight different phenolic compounds (cinnamic acid derivatives, benzoic acid derivatives, flavan-3-ols, flavanons, and eugenol) were identified and quantified in the bitter and the cherry liqueur, respectively.     

Effect of cellulose acetate gel bead column treatment on the acceptability and composition of navel orange juice

Reducing the limonin contents of pasteurised Navel orange juices by passage through a cellulose acetate gel bead column at ambient temperature significantly decreased the bitterness and increased the flavour and acceptability of the juices as measured by taste panel scores. Debittering by adsorption of limonin on to the cellulose acetate gel bed was less effective when applied to fresh unpasteurised juice and to chilled, pasteurised juice. The cellulose acetate gel column was shown to be selective for limonin, in one run removing 55% of the initial limonin content; a small quantity (12%) of flavonoids and minor amounts (< 5%) of ascorbic acid, orange oil and titratable acid were also removed but the treatment had no effect on amino acid nitrogen.