Carrot Puree Research Articles

Effect of thermal and high pressure processing on antioxidant activity and instrumental colour of tomato and carrot purées

article i nfo Article history: Received 19 May 2008 Accepted 27 September 2008 Total antioxidant activity, levels of bio-active compound groups and instrumental colour of tomato and carrot pureesubjectedtohighpressuretreatment(400-600MPa/15min/20°C)andthermaltreatments(70°C/2min) were measured. Antioxidant activity in tomato and carrot puree was significantly higher (pb0.05) than in untreated or thermally processed samples. High pressure treatments at 600 MPa retained more than 90% of ascorbic acid as compared to thermal processing in tomato purees. Heat treatments caused a rapid decrease in ascorbic acid (pb0.05). Phenolic contents were in general un-affected by thermal or high pressure treatments. Colour parameters were significantly affected (pb0.05) by thermal and high pressure processing. Principal component analysis (PCA) revealed that the first two components represented 97% and 92% of the total variability in instrumental colour parameters with respect to processing for tomatoes and carrots respectively. Industrial relevance: This research paper provides scientific evidence of the potential benefits of high pressure processing in comparison to thermal treatments in retaining important bioactive compounds. Antioxidant activity (ARP), ascorbic acid, and carotenoids after exposure to high pressure treatments (400-600 MPa) were well retained. Our results also show that redness and colour intensity of purees were better preserved by high pressure processingthan conventionalthermal treatment. Itwouldappear fromanutritional prospective,high pressure processing is an excellent food processing technology which has the potential to retain compounds with health properties in foods. Therefore high pressureprocessed foods could be sold at a premium over their thermally processed counterparts as they will have retained their fresh-like properties.

Overcoming issues associated with the scale-up of a continuous flow microwave system for aseptic processing of vegetable purees

Continuous flow microwave heating is a promising alternative to conventional heating for aseptic processing of low-acid vegetable purees. However, non-uniform temperature distribution and control of processing parameters are the major hurdles in the implementation of continuous flow microwave heating. This study was undertaken to overcome issues associated with the scale-up of a continuous flow microwave system from pilot plant scale to industrial scale and to conduct extended run times of 8 h based on the procedure developed. Dielectric properties and cross-sectional temperature profiles were measured during processing of green pea puree and carrot puree from 20 to 130 °C in a 5-kW continuous flow microwave system. During processing of green peas, cross-sectional temperature differences of 8.6 and 5 °C were observed at the outlet for center temperatures of 50 and 130 °C respectively. These temperature differences were 32.9 and 3.6 °C for carrot puree. For process scale-up, green pea puree and carrot puree were processed in a 60-kW microwave system with the objective of successful operation for at least 8 h. Static mixers, installed at the exit of each of the microwave applicators, improved temperature uniformity for both purees. Successful completion of processing the purees for 8 h in the 60-kW microwave system showed the potential for the scale-up of a continuous flow microwave system from pilot plant scale to industrial scale.

Determination of Arsenic, Cadmium, Mercury, and Lead by Inductively Coupled Plasma/Mass Spectrometry in Foods after Pressure Digestion: NMKL Interlaboratory Study

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.06-21.4 for As, 0.03-28.3 for Cd, 0.04-0.6 for Hg, and 0.01-2.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.

Quantitative studies and sensory analyses on the influence of cultivar, spatial tissue distribution, and industrial processing on the bitter off-taste of carrots (Daucus carota l.) and carrot products.

Although various reports pointed to 6-methoxymellein (1) as a key player imparting the bitter taste in carrots, activity-guided fractionation experiments recently gave evidence that not this isocoumarin but bisacetylenic oxylipins contribute mainly to the off-taste. Among these, (Z)-heptadeca-1,9-dien-4,6-diyn-3-ol (2), (Z)-3-acetoxy-heptadeca-1,9-dien-4,6-diyn-8-ol (3), and (Z)-heptadeca-1,9-dien-4,6-diyn-3,8-diol (falcarindiol, 4) have been successfully identified. In the present study, an analytical procedure was developed enabling an accurate quantitation of 1-4 in carrots and carrot products. To achieve this, (E)-heptadeca-1,9-dien-4,6-diyn-3,8-diol was synthesized as a suitable internal standard for the quantitative analysis of the bisacetylenes. On the basis of taste activity values, calculated as the ratio of the concentration and the human sensory threshold of a compound, a close relationship between the concentration of 4 and the intensity of the bitter off-taste in carrots, carrot puree, and carrot juice was demonstrated, thus showing that compound 4 might offer a new analytical measure for an objective evaluation of the quality of carrot products. Quantitative analysis on the intermediate products in industrial carrot processing revealed that removing the peel as well as green parts successfully decreased the concentrations in the final carrot puree by more than 50%.

Effect of Cell Wall Degrading Enzymes on In Vitro Carotene Accessibility in Lactic Acid Fermented Carrot Beverage

ABSTRACT: Carrot purées with different particle size were prepared from fresh carrots using 2 different food processors. The purées were fermented with lactic acid bacteria (Lactobacillus plantarum) with and without addition of cell wall degrading enzymes (Pectinex® Ultra SP‐L and CellubrixTM L). The bioaccessibility of carotenes was estimated using an in vitro digestion method. In carrots processed to a particle size <1.5 mm, the in vitro β‐carotene accessibility was 46% and neither fermentation nor addition of cell wall‐degrading enzymes had any further effect on the in vitro accessibility. In carrot purées with a coarser particle size, the in vitro β‐carotene accessibility was 18%; that significantly increased by adding high amounts of cellulases or pectinases or a combination of the enzymes either in low or high amounts. The improved accessibility was correlated with reduced particle size of the carrot purée.

Structural and sensory characterization of compounds contributing to the bitter off-taste of carrots (Daucus carota L.) and carrot puree.

Sequential application of solvent extraction, gel permeation chromatography, and HPLC in combination with taste dilution analyses revealed that not a sole compound but a multiplicity of bitter tastants contribute to the bitter off-taste of cold-stored carrots and commercial carrot puree, respectively. Among these bitter compounds, 3-methyl-6-methoxy-8-hydroxy-3,4-dihydroisocoumarin (6-methoxymellein), 5-hydroxy-7-methoxy-2-methylchromone (eugenin), 2,4,5-trimethoxybenzaldehyde (gazarin), (Z)-heptadeca-1,9-diene-4,6-diin-3,8-diol (falcarindiol), (Z)-heptadeca-1,9-diene-4,6-diin-3-ol (falcarinol), and (Z)-3-acetoxy-heptadeca-1,9-diene-4,6-diin-8-ol (falcarindiol 3-acetate) could be identified on the basis of MS as well as 1D- and 2D-NMR experiments. Due to the low concentrations of <0.1 mg/kg and the high taste thresholds found for eugenin and gazarin, these compounds could be unequivocally excluded as important contributors to the bitter taste of carrots. Calculation of bitter activity values as the ratio of their concentration to their bitter detection threshold clearly demonstrated that neither in fresh and stored carrots nor in commercial carrot puree did 6-methoxymellein contribute to the bitter off-taste. In contrast, the concentrations of falcarindiol in stored carrots and, even more pronounced, in carrot puree were found to be 9- and 13-fold above its low bitter detection concentration of 0.04 mmol/kg, thus demonstrating that this acetylenic diol significantly contributes to the bitter taste of the carrot products investigated.

Ohmic heating behaviour and electrical conductivity of two-phase food systems

Ohmic heating behaviour and electrical conductivity (EC) of two-phase food systems were studied. Food systems were comprised of a liquid phase using 4% w/w starch solution with 0.5% w/w salt, and a solid phase containing carrot puree and cubes of different sizes (6 and 13 mm) in different concentrations (30 and 50% w/w). A set of experiments was carried out for a wide range of particle concentrations from 0 to 60% w/w. With respect to the particle location, experiments were conducted using 30% w/w cubes (6 mm) placed in parallel, in series and in well-mixed conditions with the liquid phase. Ohmic heating was applied to the food systems using a static cell (20-mm-long Teflon cylinder with 35 mm diameter and 25 mm wall thickness) at a constant voltage gradient of 12.5 V/cm. Electrical conductivity values were calculated as a function of particle size, concentration, location and temperature. It was observed that the heating time increased along with particle size and concentration. Overall values of EC ranged from 0.2 to 1.8 S/m, increasing with the process temperature as it ranged from 20–80 °C, and decreasing as particle size or concentration increased. With respect to the particle location within the ohmic cell, the thermal behaviour was different when the two phases were in parallel, in series or in mixed condition. However, there was no significant difference between overall values of EC when liquid and solid phases were separated as compared with the mixed condition.

Working up a lactofermented vegetable product

The combination of lactofermentation and enzyme-treatment (Rohament-PL as endo-polygalacturonase and the mixture of Rohament-PL and Rohalase 7069 as cellulase) of sliced carrot and orange juice resulted in a homogeneous product, with pleasant organoleptic features, after 18 h fermentation period. Two ways of inoculation were applied with Lactobacillus plantarum. The addition of Rohament-PL, even at 150 mg kg-1 concentration, simultaneous inoculation with Lactobacillus plantarum (circumstances: 28 °C, 80 r.p.m. shaking) promoted the growth of lactobacilli. By 42 h fermentation time LAB count increased up to 3.2-4.8×109 cm-3. Furthermore the surface colour of the samples was more intensive (higher L-, a- and b-values) than without Lactobacillus plantarum inoculation. The application of Rohament-PL (50-100 mg kg-1) resulted in a homogeneous carrot puree, the combination of Rohament-PL (150 mg kg-1) and Rohalase 7069 (150 mg kg-1) in the process gave a more fluid product, as proved by the lower specific viscosity values.

Quality Retention in Strawberry and Carrot Purees Dried with Refractance WindowTM System

ABSTRACT: The quality retention characteristics of strawberry and carrot purees dried using the Refractance WindowTM (RW) drying method were evaluated against freeze drying, drum drying, and spray drying methods. Ascorbic acid retention of the strawberry purees (94.0%) after RW drying was comparable to 93.6% in freeze‐drying. The carotene losses for RW drying were 8.7% (total carotene), 7.4% (α‐carotene), and 9.9% (β‐carotene), which were comparable to losses of 4.0% (total carotene), 2.4% (α‐carotene), and 5.4% (β‐carotene) for freeze‐dried carrot purees. The color of the RW‐dried carrot purees was comparable to fresh puree. For RW‐dried strawberry purees, the color retention was comparable to freeze‐dried products. RW drying altered the overall perception of aroma in strawberries.

α- and β-Carotene from a Commercial Carrot Puree Are More Bioavailable to Humans than from Boiled-Mashed Carrots, as Determined Using an Extrinsic Stable Isotope Reference Method

The extent to which processing affects the carotene or vitamin A value of foods is poorly understood. An extrinsic reference method was used to estimate the mass of carotenes and vitamin A derived from various preparations made from the same lot of carrots. Using a repeated-measures design, nine healthy adult subjects consumed test meals of either carrot puree (commercial baby food) or boiled-mashed carrots on separate days; six of the subjects also consumed a test meal of raw-grated carrot. Test meals supplied 34.7 micromol (18.6 mg) carrot beta-carotene (beta C), plus 6 micromol deuterium-labeled retinyl acetate (d(4)-RA) in oil solution. Baseline-adjusted carotene and retinyl ester (R-ester) area-under-curve (AUC) responses in the triacylglycerol-rich lipoprotein (TRL) fraction (0-8.5 h) were determined using HPLC and gas chromatography-mass spectrometry. The masses of absorbed beta C, alpha-carotene (alpha C) and R-ester were estimated by comparing their AUC values with that of deuterium-labeled retinyl ester (d(4)-R-ester), assuming the latter represented 80% of the d(4)-RA reference dose. Absorption of beta C and alpha C was approximately twofold greater from carrot puree than from boiled-mashed carrots, whereas the retinol yield was only marginally (P = 0.11) influenced by treatment. Carotene and R-ester absorption from raw-grated carrot was intermediate to, and did not differ significantly from the cooked preparations. The vitamin A yield (puree, 0.53 mg; boiled-mashed, 0.44 mg) of cooked carrot containing 18.6 mg beta C was substantially less than that predicted by current convention and limited primarily by intestinal carotene uptake. Processing can therefore significantly improve bioavailability of carrot carotenes, and in some cases influence the carotene value more than the intrinsic vitamin A value.

The use of commercial pectinase in fruit juice industry. Part 3: Immobilized pectinase for mash treatment

Enzymatic mash treatment is a well-known modern process for gaining more juice from fruits and vegetables. According to the technique, cell wall and middle-lamina pectin of the fruit are degraded by pectinase activities. Besides increasing press capacity and the yield of juice up to 20%, it has also a positive effect to achieve high carotene and dry matter content of the product. The aim of the research was to investigate the activity and reusability of immobilized commercial pectinase named as “Pectinex Ultra SP-L” on carrot puree. Immobilization process was carried out by using ion exchange resin particles washed with 0.05 M phosphate buffer at pH 4.5. Pectinase activity of immobilized enzyme was determined by the measurement of viscosity reduction of pectin solution model system at pH 4.5 and 35°C and found to be 1.252-pectin (w/v, %)/s ml. Activity loss was only 20% after nine batches run model system studies. The optimum initial enzyme concentration was detected by measuring the highest pectinase activity in pectin solution and found to be 6% (v/v). Enzyme immobilized particles were added to the carrot puree with an amount of 1.5 g particle/100 g puree at pH 4.5 and 35°C to degrade soluble and insoluble pectin and haze-provoking polysaccharides. The activity of immobilized enzyme was determined by measuring pH, dry matter content and viscosity of the puree. Immobilized enzyme preparation reduced the viscosity of the carrot puree from 90 to 6.5 Poise, after 60 min of incubation. While the viscosity and pH of the puree were decreased, dry matter content and total yield were found to be increased because of the polysaccharide degradation. An average yield increment was 30.23% with respect to the yield obtained from non-enzymic processed carrot juice. Immobilized enzyme was used 5 times in carrot puree medium at the above described conditions and the activity loss was found to be only 6.5%. Activity of the immobilized enzyme was quite stable.

Antioxidant changes and sensory properties of carrot puree processed with and without periderm tissue.

Carrot purees were thermally processed with and without the periderm tissue after a long and short blanch time, with and without vacuum deaeration treatments. Samples were stored at an elevated temperature (40 degrees C for 4 weeks) to determine physicochemical changes affecting antioxidant activity (AOX), as measured by the coupled oxidation of beta-carotene and linoleic acid assay, and overall quality characteristics. Differences in AOX between treatments before thermal processing and during storage were associated with increased levels of phenolic acids and the subsequent development of numerous compounds thought to be oxidation products of phenolic acids. Samples processed with periderm tissue contained higher levels of phenolic acids, total carotenoids, and sugars than samples processed without periderm tissue. Strained carrot color was adversely affected by a long blanch time compared to a short blanch in treatments with and without periderm tissue, indicating improved color with reduced preprocessing heating. Sensory analyses by a quantitative descriptive analysis panel indicated increased musty/moldy and terpene flavors in samples processed with periderm tissue that were seemingly related to elevated levels of phenolic acids and volatile terpenoids. Terpenoid levels were reduced with deaeration steps prior to thermal processing. Processing carrots without removal of periderm tissue has proven to be a viable option when short blanch times and deaeration steps are employed.

Determination and distribution of 6-methoxymellein in fresh and processed carrot puree by a rapid spectrophotometric assay.

Isocoumarin or 6-methoxymellein (6-MM) was extracted from carrot tissue using alkali saponification to solubilize the lactone portion of its structure into an aqueous phase. Acidification and subsequent organic solvent extraction allowed isolates to be quantified and verified as 6-MM by spectrophotometric determination. 6-Methoxymellein was analyzed in carrot cross sections, as a function of depth and before and after thermal processing. A natural propensity for 6-MM accumulation was observed in root tip sections exposed to ethylene, and levels increased as a result of wounding. Consecutive layer peeling demonstrated that small-diameter roots accumulated greater amounts of 6-MM in periderm tissue compared to large roots. Processing carrots into a puree resulted in 10-25% greater extraction of 6-MM than grinding fresh carrot samples, whereas steam-cooked and thermally processed purees had 15% greater extraction than unheated purees. This analytical technique will allow carrot processors to accurately estimate raw and processed products for the bitter compound 6-MM.

Phenolic autoxidation is responsible for color degradation in processed carrot puree.

Strained carrots were thermally processed with reduced oxygen pretreatments and exposed to elevated storage temperatures to accelerate physicochemical changes (40 degrees C for 4 weeks). Strained carrot pretreatments prior to processing included a nitrogen sparge (N(2)), blanch/frozen with nitrogen sparge (BFN(2)), oxygen sparge (O(2)), and a control (C) that received no pretreatment. Changes in color, total soluble phenolics, total carotenoids, phenolic acid molecular weight, sugars, and pH were monitored during storage. Greater losses of color, total soluble phenolics, and total carotenoids occurred in control and O(2)-sparged samples as compared to N(2)-sparged and BFN(2) samples. Molecular weight of phenolic acids was lower in nitrogen-sparged samples than control and oxygen-sparged samples. Phenolic polymerization due to autoxidation was responsible for color loss in processed strained carrots. Processing treatments that reduce residual oxygen may result in better color retention after processing and during storage. Determining the mechanism(s) and magnitude of these reactions are important for devising strategies to prevent quality loss in strained carrots.

Chemical and sensory quality of processed carrot puree as influenced by stress-induced phenolic compounds.

Physicochemical analysis of processed strained product was performed on 10 carrot genotypes grown in Texas (TX) and Georgia (GA). Carrots from GA experienced hail damage during growth, resulting in damage to their tops. Measurements included pH, moisture, soluble phenolics, total carotenoids, sugars, organic acids, and isocoumarin (6-MM). Sensory analysis was conducted using a trained panel to evaluate relationships between chemical and sensory attributes of the genotypes and in carrots spiked with increasing levels of 6-MM. Preharvest stress conditions in GA carrots seemed to elicit a phytoalexic response, producing compounds that impacted the perception of bitter and sour flavors. Spiking 6-MM into strained carrots demonstrated the role bitter compounds have in lowering sweetness scores while increasing the perception of sour flavor. Screening fresh carrots for the phytoalexin 6-MM has the potential to significantly improve the sensory quality of processed products.

Reduction of nitrate and nitrite in vegetable juices prior to lactic acid fermentation

Summary The reduction of the nitrate content in vegetable juices has an important effect on the total intake of nitrate by humans. Carrot puree containing 500 mg/1 nitrate was treated with immobilized cells of Halomonas spec, at 6°C. The nitrate was reduced within five hours quantitatively to nitrous oxide. Lactic acid fermentation by Leuconostoc mesenteroides performed after completion of the denitrification process led to a product with pleasant and typical flavour.

A POTENTIAL PROCESSED CARROT PRODUCT

ABSTRACTCarrot pie fillings were prepared from carrots that did not meet fresh market standards but were otherwise of good quality. The pie fillings were prepared by mixing carrot puree, sugar, salt, and ground spices or oil extract spices. Nutrient composition analysis showed that vitamin A was five times higher in carrot pie fillings than in pumpkin pie filling. Thiamin, niacin, and total carbohydrates were higher in carrot pie fillings. Sensory panel scores show that carrot pie was preferred over pumpkin pie and ground spices over oil extract spices. The results of this work indicate that an acceptable carrot pie filling of equal or better nutritional value than pumpkin pie can be prepared.

CARROT BEVERAGES

ABSTRACTBeverages were prepared from combinations of carrot juice, carrot puree, whole orange puree, grapefruit and pineapple juices, lemon juice concentrate, sugar, citric and ascorbic acids and artificial pineapple and orange flavors. The beverages were stored at 20°C for 9 months. Analytical determinations for pH, acid, Brix, β‐carotene, ascorbic acid, color and flavor evaluations were made at intervals of 0, 1, 2, 4, 6 and 9 months. The major nutrient lost during processing and storage was ascorbic acid. Storage time had no effect on the other quality factors. Taste testers consistently rated the carrot‐orange puree plus pineapple juice beverage as having the most desirable flavor and plain carrot juice, the least desirable flavor.

Organic Acid Profiles of Thermally Processed Carrot Puree

The aim of this investigation was to examine changes in organic acid concentration in carrot puree during processing at temperatures ranging from 240–300 F, with 20 F increments and an F0 equal to 4.9. Two varieties of carrots from two different geographical regions were packed in Thermal Death Time (TDT) tubes, flushed with nitrogen, sealed, and processed. Following this, analyses were conducted to determine changes in organic acid content and pH. Significant increases in pyrrolidone carboxylic acid (PCA), citric acid, fumaric acid, acetic acid, and malic acid were noted between the fresh product and product processed at 240 F. The PCA concentration was significantly affected by changes in processing temperature, while pyruvic and fumaric acids exhibited possible variations. The greatest change in pH from the fresh (unheated) product occurred with the 240 F processed product in both Texas and California samples. As the processing temperature increased, with a constant F0 value, the pH decreased. The pH readings for the carrot samples from the two different locations were similar.

GLUTAMINE AS A PREDICTIVE MEASUREMENT IN THE QUALITY ASSESSMENT OF PROCESSED CARROT PUREE

The aim of this investigation was the development of a simple quality test whereby knowing the amount of glutamine present in a fresh sample of carrots and the processing temperature, the amount of PCA and perhaps the acceptability of the final product might be determined. Two different varieties of carrots from two different geographical locations were packed in TDT tubes, flushed with nitrogen and sealed. A process of Fo= 4.9 was given to each series of tubes at temperatures ranging from 240‐300°F with 20°F increments. Following this, analyses were conducted for glutamine, pyrrolidone‐carboxylic acid (PCA) and pH to determine the effect of initial concentration of glutamine and process temperature upon the formation of PCA. Taste thresholds for PCA were also determined both in model systems and in processed carrot puree. PCA formation was found to exhibit an inverse linear semilogarithmic plot with process temperature such that amounts could be predicted from initial glutamine contents for a given batch. Sensory studies indicated that the levels of PCA found in samples at the lower temperatures were near the taste thresholds established for this compound. With such results it is possible to predict the best process time and temperature for carrot puree based on the initial concentration of glutamine in order to minimize off‐flavors due to PCA formation.