Valencia Orange Juice Research Articles

Temperature–time relationships for thermal inactivation of pectinesterases in orange juice

AbstractThe first‐order kinetic model of a two‐component system was applied to calculate the necessary parameters using the commercial Mathcad program package during the experimental thermal pasteurisation of Valencia orange juice. Thermostable and thermolabile pectinesterases, accounting for 6.6 and 93.4% of the total enzyme population in the juice respectively, showed a 5.63 °C Zs value and a 9.54 °C Zl value respectively from the thermal destruction curves at temperatures ranging from 75 to 90 °C. The calculated Zs values were consistent with the literature values for Valencia orange juice. The calculated and experimental non‐linear thermal pasteurisation curves for orange juice were also in good agreement at temperatures between 75 and 90 °C.© 2003 Society of Chemical Industry

Effect of thermal pasteurization on Valencia orange juice color and pigments

Changes in carotenoid pigment content and juice color due to thermal pasteurization of Valencia orange juices were studied. Total carotenoid pigment content loss was significant ( P<0.05) after thermal pasteurization at 90°C for 30 s. Thermal effects on carotenoid pigment contents, especially on violaxanthin (−46.4%) and antheraxanthin (−24.8%), were clearly observed. With the loss of violaxanthin and antheraxanthin, lutein became the major carotenoid, followed by zeaxanthin, in pasteurized Valencia orange juice. There was perceptible color change after orange juice pasteurization, which led to juice color becoming lighter and more saturated. Decreases in CIE a* value and increases in CIE L*, b*, h*, and C* are the major color changes after pasteurization. Overall increases in reflected light might also influence the perception of color to a great extent in pasteurized orange juice. Total color differences (Δ E*) compared to the fresh juice was 2.92±0.97 ( P<0.05).

Effects of Carbon Dioxide in High‐Pressure Processing on Pectinmethylesterase in Single‐strength Orange Juice

ABSTRACT: High‐pressure processing (HPP) in combination with added CO was examined for efficacy in inactivating Valencia orange juice pectinmethylesterase (PME). Noncarbonated juice and carbonated juice were subjected to a range of conditions from 200 to 600 MPa, 30 to 300 s dwell time at pressure, and 15 to 50 °C at final processing temperature. Processing pressure magnitude, temperature, and dwell time were significant factors (p &lt; 0.001) in the inactivation of PME. At 600 MPa and 25 °C final processing temperature, the addition of 12 psig carbon dioxide resulted in a decrease of pressure processing time from 346 s to 111 s, while achieving an equivalent reduction in PME activity.

A pectinmethylesterase gene associated with a heat-stable extract from citrus.

A putative thermostable pectinmethylesterase (TSPME) protein of 36 kDa was isolated from heat-treated citrus finisher pulp. After purification and partial sequencing of the protein, a reverse genetic approach was used to obtain the complete genomic sequence of a new pectinmethylesterase (PME) gene, CsPME4, from Citrus sinensis (L.) Osb. cv. Valencia. The CsPME4 gene contained two exons of 1203 and 690 bp interrupted by a single positionally conserved intron of 1230 bp. A full-length CsPME4 cDNA clone amplified from Valencia orange juice vesicles shared 98% identity with the genomic clone. The encoded protein of the full-length CsPME4 cDNA shared 66 and 39% amino acid identity with the full-length encoded proteins of the citrus PME, CsPME1, and CsPME3, respectively, whereas the predicted mature protein of CsPME4 shared 80 and 61% identity with the predicted mature proteins of CsPME1 and CsPME3, respectively. Southern analysis demonstrated that CsPME4 was present in at least two copies in the Valencia orange genome. Northern analysis revealed that CsPME4 mRNA was accumulated mainly in young and developing tissues of Valencia orange. Several approaches to express recombinant CsPME4 in different systems failed to obtain active protein. Further research will be necessary to successfully express the putative TSPME gene CsPME4 for biochemical characterization.

Potential of semiconductor sensor arrays for the origin authentication of pure Valencia orange juices.

Sensor array is a new method used in aroma analysis. This technique was employed for the differentiation of 49 pure Valencia orange juices from 5 different origins representative of the main culture areas of citrus according to their volatile organic fractions. An experimental design was used to set analytical factors, which control the generation of the static headspace; therefore, the preliminary optimization of analytical conditions allows the evaluation of the potential of such an apparatus in this kind of survey. Results obtained were then statistically treated by multivariate analyses such as principal component analysis and factorial discriminant analysis. Sensor arrays performed a good discrimination of the whole juices in classing them according to the origin of Valencia oranges used. A calibration of the sensors was then performed to build a database aiming to classify the juices according to the origin of oranges involved. New supplementary samples were then analyzed to assess the efficiency of the database. This technique coupled with other ones such as high-pressure liquid chromatography and gas chromatography may be a new tool for the investigation of adulteration detection due to the authentication of the origin of raw materials employed in the orange juice processes.

Involvement of proteins in cloud instability of valencia orange [Citrus sinensis (L.) Osbeck] juice.

The present study examined the involvement of proteins in cloud flocculation of Valencia orange juice. Marked differences in cloud instability were found between juices of different harvest dates. Heating of enzymatic pectin degraded juice from April and June harvests resulted in development of clumps and their precipitation. Although the juice from both harvesting dates remained hazy, the juice of April harvest was more turbid than that from June. Usually clarification increases as the temperature increases from ambient to 125 degrees C. Clarification occurred at pH 2.5-4.5 and was maximal at pH 3.5. The clarification of the April harvest juice was markedly lower than that of the June harvest. The fresh juice contained about 5.2 and 1.7 mg mL(-1) insoluble cloud matter (ICM) and alcohol-insoluble serum solids (AISS), respectively. The ICM and the AISS, respectively, contained: proteins (244.5+/-8.7 and 132+/-1.8 microg mg(-1)), galacturonic acid (40+/-0 and 120+/-0 microg mg(-1)) and neutral sugars (270+/-39 and 329+/-23 microg mg(-1)). Enzymatic pectin degradation resulted in removal of a marked portion of the pectin, and was accompanied by partial removal of neutral sugars (mainly glucose and galactose) and some proteins from the pectic polymer in both AISS and ICM. Proteins of the AISS included major bands at 10-14, 20, and 28 kDa and those of the ICM bands at 22, 24, 26, and 45 kDa.

Determination of the geographical origin of valencia orange juice using carotenoid liquid chromatographic profiles

We present a simultaneous liquid chromatographic method for quantitation of the major carotenoid pigment in pure valencia orange juice from two country origins. This technique involves the use of a C 30 non-endcapped reversed-phase column and a ternary gradient, methanol–methyl tert.-butyl ether–water. Identification of carotenoids is achieved using a photodiode array detection at 350, 430 and 486 nm. The spectra of saponified carotenoid pigments from 23 orange juices samples were compared and discussed in the context of results that were published previously. The behaviour of the C 30 column with time, on the resolution of two carotenoids, zeaxanthin and isolutein is discussed. This technique has been applied to the determination of the geographical origin of carotenoid compounds using eighteen samples of valencia pure orange juice from two countries (Belize and Spain), collected over two consecutive years. Quantitative determination seems to be a convenient method for determination of the origin of orange juice. The total carotenoids considered were higher in valencia juice from Spain (17.0±5.0 mg l −1) than in valencia juice from Belize (4.8±1.0 mg l −1). Some carotenoids play a large role in origin differentiation, such as phytofluene, which is lower from Belize than from Spain (0.5 vs. 1.8%), or ξ-carotene, which is higher in valencia from Spain (4.9%) than in valencia from Belize (1.8%).

Orange Juice Quality After Treatment by Thermal Pasteurization or Isostatic High Pressure

Valencia orange juice was treated by traditional thermal pasteurization, high pressure processing, and a combination of the two prior to storage at 4 and 8 °C. The flavor of pressure treated juice (without additional heat) stored at 4 °C up to 16 wk or 8 °C up to 4 wk was significantly (α = 0.05) closer to that of fresh/frozen juice than any of the thermal treatments. Juice microflora was reduced to below detectable limits; however, pectinmethylesterase retained substantial activity in pressure treated juices. There was little effect on other juice quality parameters.

Retention of volatile organic flavour/fragrance components in the concentration of liquid foods by osmotic distillation

Nine types of hydrophobic microporous membranes were tested for their influence on the retention of a range of volatile organic species when model aqueous solutions of the latter were subjected to osmotic distillation. Similar studies were carried out on Gordo grape juice and Valencia orange juice. Gas chromatography–mass spectrometry head-space analyses of the feed materials coupled with scanning electron microscopy and image analyses of the membranes used indicated that lower organic volatiles flux to water flux ratios occurred when pore sizes at the membrane surface were relatively large. The results have been interpreted in terms of differences in feed-membrane and stripper-membrane boundary layer resistances to organic volatiles transport resulting from different degrees of liquid intrusion into the membrane pores.

Genetics and expression of two pectinesterase genes in Valencia orange

The genetics and expression of pectinesterase (PE) genes were examined in Valencia orange. Degenerate primers based on partial amino acid sequence of a 36 kDa PE protein isolated from juice vesicles were used to amplify a 350 bp DNA fragment from cDNA prepared from juice vesicle total RNA. Two groups of 350 bp PE clones with 66% sequence identity were isolated. A clone from each group was used to screen a Valencia orange genomic DNA λ library. Two different lambda clones that contained complete PE coding sequence (CsPME1 and CsPME3) and a third lambda clone that contained partial PE sequence (CsPME2) were characterized. The CsPME1 gene contained two exons (1063 and 689 bp) interrupted by a 1452 bp intron, whereas the CsPME3 gene had two exons (844 and 686 bp) interrupted by a 771 bp intron. CsPME1 shared significant sequence similarity with the partial clone CsPME2, including the entire cloned region of the first exon, a large region in the 5′ portion of the intron and the 3′ portion of the second exon, but the 3′ portion of the intron and the 5′ portion of the second exon were dissimilar. Southern blots suggested that Valencia orange has two genes within each PE group. Full‐length cDNA clones that shared 99% sequence identity with CsPME1 and CsPME3 were isolated. Both groups of PE genes were differentially expressed in tissues of Valencia orange, and in addition CsPME3 appeared to be ethylene‐regulated. The deduced proteins of PE cDNA clones CsPME1 (63.5 kDa) and CsPME3 (56.3 kDa) were considerably larger than the PE protein we isolated from Valencia orange juice vesicles and also other mature plant PE proteins. The estimated size of group I (2.2 kb) and group II (2.0 kb) PE mRNAs also predicted a larger protein than was isolated from juice vesicles. Alignment of the mature tomato and mung bean PE proteins, the most N‐terminal sequence we obtained from polypeptides derived from the 36 kDa PE isolated from juice vesicles and the deduced amino acid sequences of plant PE cDNA clones suggest that a post‐translational cleavage event separates the variable N‐terminus from the more conserved C‐terminal domain of the mature PE protein.

FLAVOR AND CHEMICAL COMPARISON OF PASTEURIZED AND FRESH VALENCIA ORANGE JUICES1

ABSTRACTFreshly extracted Florida Valencia orange juice was heated at 98C for 11 s to produce lightly heated juice, and for 37 s to produce heavily heated juice. Sensory panels detected a flavor difference between the fresh, unheated juice and the heavily heated juice. Analyses of these two juice samples by headspace gas chromatography (GC) showed no significant qualitative or quantitative differences. GC analyses of methylene chloride extracts of juices and of residues from distillation of the juices showed only one detectable difference in each case. Extracts of the whole juices showed one GC peak, which was significantly larger in the heavily heated juice, identified as the potential off flavor compound, octanoic acid. Extracts of the high‐boiling distillation residue showed one unidentifed late‐eluting GC peak which appeared only in the heavily heated juice. These findings supplement previous reports that more severe pasteurization conditions than required for juice processing cause detectable flavor changes in heated juice.

RETENTION OF FRESH ORANGE JUICE FLAVOR AND AROMA IN AN AQUEOUS DISTILLATE FROM VALENCIA ORANGE JUICE1

ABSTRACTFreshly squeezed Valencia orange juice, distilled at low temperature and reduced pressure, yielded an aqueous distillate with the necessary balance of volatile flavor and aroma constituents to retain the fresh juice characteristics. Flavor comparisons by an experienced sensory panel determined that orange juice reconstituted by combining the aqueous distillate with the residual juice solids had significantly more fresh juice character than reconstituted commercial frozen concentrated orange juice; commercial not pasteurized single strength orange juice (SSOJ); pasteurized SSOJ, not from concentrate; canned SSOJ, from concentrate; or aseptically packed SSOJ, from concentrate. The panel also found no significant difference in fresh juice characteristics between freshly squeezed orange juice and distillate and residual solids recombined from the same juice sample. Fifty four volatile constituents were identified from the aqueous distillate of freshly squeezed orange juice.

Portable, low‐cost equipment for small‐scale fruit juice processing

SummarySimple, low‐cost portable equipment to extract citrus juice, and pasteurize it and other fruit juices by passing through a coil of stainless steel tube in boiling water was designed, constructed and tested. Temperature reached was varied by altering the hydrostatic feed height, and the product was directly hot‐bottled and capped. Pasteurization was microbiologically effective, and had little effect on ascorbic acid, furfural and colour of freshly prepared pineapple orange, Valencia orange and apple juices, and an orange squash drink, and only the expected changes occurred on storage at 21°C for periods up to 6 months, although with no indication of microbial activity. Taste panel ratings showed a loss of liking for treated orange juice, but not for apple. The equipment is suitable for improved utilization of crops by community technology in less‐developed areas.

Struktur der Valenciaxanthine und Valenciachrome

Structure of the Valenciaxanthins and ValenciachromesValenciaxanthin, a carotenoid first isolated from Californian Valencia orange juice in 1952/1954 by American scientists, was re‐isolated from fresh Spanish ‘Navelinas’ and shown, by spectroscopical and chiroptical examination, to have the unexpected (9Z)‐10′‐apo‐11′,12′‐dihydroviolaxantin‐10′‐ol structure 6. A further, very minor component represents the (all‐E)‐structure 7. Therefore, the Valenciachromes are the furanoid rearrangement products of 6 and 7 and, thus, stereoisomers of the 10′‐apo‐11′,12′‐dihydroauroxanthiiv 10′‐ols 8. Valenciaxanthin represents a modification of the common cleavage of carotenoids in higher plants according to the scheme C40 → C27 + C13, insofar as the reduction step not only includes the aldehyde function but also the subsequent conjugated double bond.

A simple headspace-gas chromatographic method for the quantitative determination of organic volatiles of fresh orange juice

A fast quantitative method of determination of acetaldehyde, ethyl acetate, methanol and ethanol, in freshly squeezed Valencia orange juice using headspace-gas chromatography was developed. Filtered and unfiltered juices could be analysed using standard addition and direct calibration methods.

Liquid chromatographic profiles of major carotenoid esters in commercially processed california navel and valencia orange juice concentrates

A procedure for establishing profiles of major carotenoid esters in commercially processed Valencia and Navel orange juice concentrates by reversed-phase liquid chromatography (LC) using Sudan 1 as internal standards is described. The procedure involved conversion of 5,6-epoxides in heat concentrated citrus juices to more stable 5,8-epoxides by treatment of extracted carotenoids with hydrochloric acid followed by dual wavelength analyses at 400 and 465 nm using LC. The esters of 5,8-furanoids (auroxanthin and mutatoxanthin) were approximately quantitated at 400 nm without interference from other carotenoids. Cryptoxanthin esters and free cryptoxanthin, lutein esters, citraurin esters and carotenes were approximately quantitated at 465 nm withou interference from auoxanthin esters. The furanoid esters varied from 60 to 75% of the total carotenoids in the concentrates. The cryptoxanthin esters varied from 60 to 75% of the total carotenoids in the concentrates. The cryptoxanthin esters varied from 5 to 10% of the total carotenoids in Valencia orange juice concentrates and from 10 to 15% of the total carotenoids in Navel orange juice concentrates. Citraurin esters were present only in Navel orange juice concentrates and β-carotene content was less than 5% of the total carotenoids in both concentrates. The total carotenoids and individual carotenoids increased with the advance in season in Navel orange juice concentrates which had less than halfthe amount of total carotenoids of Valencia orange juice concentrates.

Carbohydrate and enzyme distribution in protoplasts from valencia orange juice sacs

The subcellular distribution of neutral sugars, organic acids and their metabolic enzymes was investigated in protoplasts from ‘Valencia’ orange juice sacs. The vacuole was found to contain 70% of the malic acid, 75% of the fructose and glucose, 89% of the citric acid and 100% of the sucrose. Of the enzymes assayed, α-mannosidase, phosphohexoisomerase and phosphoglucomutase showed activity in the vacuole fraction at 100, 5 and 29%, respectively. The activities of acid and neutral invertases, UDPG pyrophosphorylase and both ATP and PPi phosphofructokinase were present only in the cytoplasmic fraction. The remaining enzymes (sucrose synthase, hexokinase, fructokinase and aconitase) showed no activity in any of the samples assayed (protoplast, vacuole and cytoplasm). From the data presented, it appears that vacuolar sugars are the major form of carbohydrate supplying energy to the mature juice sac cells. Possible mechanisms of sugar transport across the tonoplast prior to their oxidation are discussed.

Quality of Freeze Concentrated Orange Juice

ABSTRACTPasteurized Valencia and Temple orange juices concentrated to 45°Brix by freeze concentration retained their fresh juice flavor. Direct steam infusion heating to inactivate enzymes allowed more rapid heating than indirect heating and successfully lowered juice peel oil during vacuum cooling. Except for considerable pulp reduction of feedstream juices, there were few differences from normal citrus juice recovery procedures for freeze concentration. Since the product retained most of the aroma constituents of fresh juice, careful handling and high quality feed juice prior to freeze concentration was much more important than for evaporation. Fresh juice freeze concentrated to 45°B, then pasteurized at temperatures of 80°, 97° and 111°C had reduced sucrose (up to 25%) as the temperature increased to 111°C.

Quality of Enzymatically Treated 72° Brix Orange Juice Stored at Refrigerated Temperatures

ABSTRACTFresh Valencia orange juice was treated with 0, 70, and 350 ppm of commercial pectic enzymes, concentrated to 72° Brix and stored at –7°, –1°, 7°, and 13°C for up to 6 months. The 70 ppm enzyme treatment successfully reduced initial apparent viscosity by about 25%. For the 70 ppm enzyme treated samples after 6 months storage at all four temperatures, juice cloud remained acceptable, furfural remained below the significant level, and at −1°C, vitamin C levels were above 32 mg/100 mL. There was no significant difference in taste after 6 months storage at −7°C between control and 70 ppm enzyme treated samples. Product quality of enzymatically treated orange concentrate stored at refrigerated temperatures was of sufficient quality to realize potential savings of 17% in storage and 30% in refrigeration.

Decreased hydrogen sulphide content in valencia oranges after freeze damage

The hydrogen sulphide content of headspace gases above freshly extracted Valencia orange juice from freeze-damaged and control fruit was determined. The average value for control fruit was about three times higher than that for fruit suffering moderate to heavy freeze damage, indicating a potential use as an indicator of freeze damage to fresh citrus fruit.