Effects of various sulphuring methods and storage temperatures on the physical and chemical quality of dried apricots

The effects of different sulphuring methods, i.e. sulphuring by “burning the elemental sulphites (BES),” “SO₂ gas from liquified SO₂ tank (SG)” and “dipping into sodium metabisulphite solution (DSM)” on the colour (brown colour formation and carotenoid degradation) and the loss of SO₂ in apricots from Hac?halilo?lu and Kabaa?? varieties stored at 5, 20 and 30 °C for a year were investigated. There were significant effects of variety, sulphuring method and especially storage at 30 °C on the brown colour formation and loss of SO₂ (P < 0.05). As storage temperature–time increased, β-carotene content decreased. Sulphuring methods and variety did not show significant effect on β-carotene content (P > 0.05). The changes in L^∗, b^∗ and C^∗ values were directly associated with β-carotene content and browning values. The most suitable method for all samples, except for Hac?halilo?lu variety stored at 30 °C (BES), is SG, because the samples retained their attractive golden yellow colour during storage.     

Thermal degradation kinetics of anthocyanins and visual colour of Urmu mulberry (Morus nigra L.)

Urmu mulberry (Morus nigra L.) juice was concentrated from 15.02 to 45.20 °Brix by rotary vacuum evaporator at 40 °C. The objectives of this study were to determine the titratable acidity, soluble solid content, antioxidant capacity, total monomeric anthocyanins and total phenolic matter in prepared concentrate, to investigate the thermal degradation kinetics of anthocyanins and Hunter colour parameters (L^∗, a^∗, b^∗) and total colour difference (TCD^∗) and to develop a relationship between visual colour and anthocyanin during thermal processing at 60, 70 and 80 °C. Monomeric anthocyanin degradation showed a first order reaction kinetics. The zero order, first order and a combined kinetics model were applied to the changes in Hunter colour parameters (L^∗, a^∗ and b^∗) and total colour difference (TCD^∗). All colour parameters followed an apparent combined kinetics model. The degradation of anthocyanins showed positive correlation with a^∗, b^∗ and L^∗ and negative correlation with TCD^∗.     

Carotenoid contents of extruded and non-extruded sweetpotato flours from Papua New Guinea and Australia

Carotenoid contents of extruded and non-extruded flours of Papua New Guinean and Australian sweetpotato cultivars were studied, using spectrophotometry and high performance liquid chromatography (HPLC). The cultivars differed (p < 0.05) in their total carotenoid and β-carotene contents, and the Original Beauregard cultivar had the highest total carotenoid and β-carotene contents among the cultivars. The spectrophotometry (84–1720 μg/g solids) method generally over-estimated the total carotenoid content compared to the more specific HPLC (23–355 μg/g solids) method. Extrusion significantly (p < 0.05) decreased the ΔL^∗ Hunter colour values, while the Δa^∗, Δb^∗, total colour change (ΔE), chroma (CR), and browning indices (BI) increased. With the extruder and screw configuration used, extrusion at 40% moisture and 300 rpm screw speed retained carotenoid maximally at more than 80%. This study reports, for the first time, carotenoids of flours from south Pacific sweetpotato cultivars, and carotenoid retention during extrusion.     

Effects of soybean oil and oxidized soybean oil on the stability of β-carotene

The effects of 1.0%, 2.5%, and 5.0% purified soybean oil and thermally oxidized soybean oil on the stability of 100 ppm β-carotene as a fat-soluble vitamin A and singlet oxygen quencher in isooctane have been studied. The samples were stored under 1000, 2000, or 4000 lx at 20 °C for 2 days and at 50 °C for 16 days in the dark. The β-carotene was determined by high-performance liquid chromatography. The centrifugation and filtration of vegetable mixture, during sample preparation for β-carotene analysis by HPLC, decreased the coefficient of variation from 4.13% to 1.02%. The purified soybean oil and thermally oxidized soybean oil stabilized β-carotene in isooctane under light and in the dark at α = 0.05. The losses of β-carotene, with 1.0% purified oil, 1.0% thermally oxidized oil and without any oil during 48 h under light, were 11.2%, 80%, and 100%, respectively. 100 ppm TBHQ had a protective effect on the stability of β-carotene in isooctane at α = 0.05. The β-carotene stability decreased as the light intensity increased from 1000 to 2000 or 4000 lx at α = 0.05. The stability of vitamins in fruit and vegetable drinks enriched with fat-soluble vitamins and antioxidants during storage can be greatly improved by adding approximately 1.0% high quality non-oxidized soybean oil.     

Isomerisation kinetics and antioxidant activities of β-carotene in carrots undergoing different drying techniques and conditions

Carrots are known as a natural source of β-carotene. In order to preserve the latter, carrots must generally be processed, and drying is one of the most common methods for processing carrots. During drying β-carotene in carrots suffers degradation. β-Carotene degradation is generally due to thermal degradation and isomerisation. In this work, the drying kinetics as well as the isomerisation kinetics and antioxidant activities of β-carotene in carrots undergoing hot air drying, vacuum drying and low-pressure superheated steam drying (LPSSD) were determined within the temperature range of 60–80 °C and, in the case of vacuum drying and LPSSD, at a pressure of 7 kPa. A high performance liquid chromatography (HPLC) method was used to determine the β-carotene contents and its isomerisation kinetics, while the antioxidant activities of various combinations of all-trans- and cis-forms of β-carotene in carrots were evaluated using the Trolox equivalent antioxidant capacity (TEAC) assay.     

Changes in oxidative stability,antioxidant capacity and phytochemical composition of Pistacia terebinthus oil with roasting

The effect of roasting on oxidative stability, antioxidant capacity and the content of antioxidant phytochemicals in Pistacia terebinthus oil was investigated. Oils were extracted from P. terebinthus fruits roasted at 180 °C for 0–40 min. Roasting was found to cause an increase in the passage of phenolic compounds to the oil whereas the level of tocopherols, lutein and β-carotene was decreased. Antioxidant capacity and oxidative stability of P. terebinthus oil increased with roasting. As an indicator of the presence of Maillard reaction products in oil, hydroxymethylfurfural (HMF) level and colour intensity was measured and found to increase with increasing roasting time. Fatty acid composition was not affected significantly by roasting.     

Effect of ripeness and postharvest storage on the evolution of colour and anthocyanins in cherries (Prunus avium L.)

The relationship between colour parameters and anthocyanins of four sweet cherry cultivars, Burlat, Saco, Summit and Van was studied. The colour (L^∗, a^∗, b^∗, chroma and hue angle parameters) and anthocyanins were analysed during two different years at two different ripening stages (partially ripe, and ripe, respectively). The cherries were analysed at harvest and after storage at 1.5 ± 0.5 °C and 15 ± 5 °C for 30 and 6 days, respectively. The colour was measured by tristimulus colourimetry (CIELAB system) directly on the fruits, while anthocyanins were quantified by HPLC-DAD analysis on methanolic extracts of freeze-dried samples of the fresh cherries and on the differently stored cherries. L^∗, chroma, and hue angle values were always lower for the ripe than for the partially ripe cherries. All of the cultivars were found to contain cyanidin-3-rutinoside and cyanidin-3-glucoside as the major anthocyanins. The total anthocyanin content in fruits of the different cultivars varied in the order Burlat > Saco > Van > Summit. The concentration of anthocyanins increased at both temperatures of storage in both ripe and partially ripe cherries, but the extent of increase varied among cultivars. Cherries stored at 15 ± 5 °C showed higher reduction of L^∗, chroma and hue angle than fruits stored at 1.5 ± 0.5 °C. L^∗, a^∗, b^∗, chroma and hue angle correlated negatively (P < 0.001) with the total anthocyanins levels, but not with the total phenols. These results show that chromatic functions of chroma and hue correlate closely with the evolution of colour and anthocyanins levels during storage of sweet cherries and indicate that colour measurements can be used to monitor pigment evolution and anthocyanin contents of cherries (and vice versa).     

Antioxidative activity of Rosmarinus officinalis L. essential oil compared to its main components

This study was designed to examine the in vitro antioxidant activities of Rosmarinus officinalis L. essential oil compared to three of its main components (1,8-cineole, α-pinene, β-pinene). GC–MS analysis of the essential oil resulted in the identification of 19 compounds, representing 97.97% of the oil, the major constituents of the oil were described as 1,8-cineole (27.23%), α-pinene (19.43%), camphor (14.26%), camphene (11.52%) and β-pinene (6.71%). The oil and the components were subjected to screening for their possible antioxidant activity by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test. In the DPPH test system, free radical-scavenging activity of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were determined to be 62.45% ± 3.42%, 42.7% ± 2.5%, 45.61% ± 4.23% and 46.21% ± 2.24% (v/v), respectively. In the β-carotene bleaching test system, we tested series concentration of samples to show the antioxidant activities of the oil and its main components, whereas the concentrations providing 50% inhibition (IC₅₀) values of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were 2.04% ± 0.42%, 4.05% ± 0.65%, 2.28% ± 0.23% and 2.56% ± 0.16% (v/v), respectively. In general, R. officinalis L. essential oil showed greater activity than its components in both systems, and the antioxidant activities of all the tested samples were mostly related to their concentrations. Antioxidant activities of the synthetic antioxidant, ascorbic acid and BHT, were also determined in parallel experiments as positive control.     

Colour degradation and quality parameters of sonicated orange juice using response surface methodology

Freshly squeezed orange juice was subjected to sonication at amplitude levels ranging from 40 to 100% at a constant frequency of 20 kHz for different times (2-10 min) and pulse durations of 5 s on and 5 s off. Hunter colour values (L^∗, a^∗ and b^∗), pH, °Brix, titratable acidity, cloud value and browning index were measured. Response surface methodology (RSM) based on two factor five level central composite design was applied to determine the effect of amplitude level and sonication time on juice quality parameters. There was no significant difference (p < 0.05) on pH, °Brix and titratable acidity. The model predictions for critical quality parameters of Hunter colour values (L^∗, a^∗ and b^∗), cloud value and browning index were closely correlated to the experimental results obtained. RSM was demonstrated to be an effective technique to model the effect of sonication on juice quality while minimising the number of experiments required.     

Peeling,drying temperatures,and sulphite-treatment affect physicochemical properties and nutritional quality of sweet potato flour

The effects of peeling, drying temperature (55–65 °C) and pretreatment on the physicochemical properties and nutritional quality of sweet potato flour were investigated. The flours were prepared from peeled and unpeeled sweet potatoes dipped in 0.5% sodium hydrogen sulphite (NaHSO₃). There were significant differences (p < 0.05) in ΔE values and browning index between flours from peeled and unpeeled sweet potatoes without sulphite-treatment (PF and UF). On the other hand, flours from peeled and unpeeled sweet potatoes with sulphite-treatment (PSF and USF) had higher L∗, a∗, and b∗ values, swelling capacity, ascorbic acid, and total phenolics than PF and UF. However, USF and UF had higher β-carotene content than PSF and PF. β-Carotene and ascorbic acid contents decreased with increasing drying temperature for all flours, whereas total phenolics increased for PSF and USF. Therefore, the best quality product was obtained when samples were pretreated with sulphite before drying at any temperature.     

Stability and colour characteristics of PEF-treated cyanidin-3-glucoside during storage

The stability and colour characteristics of PEF (pulsed electric field)-treated cyanidin-3-glucoside (Cy-3-glu) was investigated during storage at 4, 24 and 37 °C. The degradation of Cy-3-glu was analyzed using a first reaction kinetics while its colour characteristics was evaluated using colour indices such as colour density (CD) and CIE L^∗a^∗b^∗ parameters. PEF had no post-effect on the stability and colour characteristics of Cy-3-glu during storage while the storage temperature had a significant effect (p < 0.05). The degradation of PEF-treated Cy-3-glu during storage conformed to the first-order reaction kinetics with regression coefficients R² greater than 0.9300. Corresponding to 4, 24 and 37 °C, the degradation rate constant k in Cy-3-glu significantly increased in the exponential order level of 10⁻⁴, 10⁻³ and 10⁻², while the t_1/2 (the time that 50% Cy-3-glu degradation would take) and D-value (the time that 90% Cy-3-glu degradation would take) of Cy-3-glu during storage decreased in the exponential order level of 10³, 10² and 10. The reduction of CD was closely related to the Cy-3-glu content in this study, the Cy-3-glu content was perfectly predicted using CD with a higher coefficient R² > 0.9999. A significant decrease in b^∗ and H⁰ value was obtained at all storage temperature (p < 0.05). A positive correlation was found between the Cy-3-glu content and b^∗ value or H⁰ value with a coefficients R² > 0.8400 during storage. ΔE increased significantly, ΔE was less than 2 at 4 °C while it was greater than 2 at 24 and 37 °C.     

On-line color monitoring of solid foods during supercritical CO2 pasteurization

An on-line color monitoring system for solid foods to be used during supercritical carbon dioxide (SC-CO₂) pasteurization was designed and tested. The experimental apparatus described here allowed for the measurement of reflectance spectra and color parameters (L^∗, a^∗, b^∗) during (on-line) as well as before and after treatments (off-line).The results demonstrated that SC-CO₂ pasteurization applied at 12.0 MPa, 40 °C slightly affected the color of freshly cut pieces of coconut and carrot during the process performed at different treatment times (10, 20, and 30 min). Reflectance spectra of coconut, acquired on-line, showed that CO₂ influenced the color immediately upon treatment: lightness (L^∗) changed from 86.10 ± 2.80 at 1 min to 79.57 ± 0.74 at 30 min. The decompression was demonstrated to be the critical parameter affecting the color of carrot. The off-line measurements showed that 30 min of treatment induced 38% and 22% decrease of redness (a^∗) and yellowness (b^∗), respectively.The proposed apparatus allowed for a non-invasive, immediate and direct monitoring of food color before, during and after SC-CO₂ pasteurization.     

Effect of sonication on colour,ascorbic acid and yeast inactivation in tomato juice

Power ultrasound is recognised as a potential non-thermal technique to inactivate micro-organisms pertinent to fruit juices. In this study tomato juice was sonicated at different amplitude levels (24.4–61.0 μm) at a constant frequency of 20 kHz for treatment times (2–10 min) and pulse durations of 5 s on and 5 s off. Hunter colour values (L∗, a∗ and b∗), pH, °Brix, titratable acidity, ascorbic acid and yeast inactivation were measured. No significant differences (p < 0.05) in pH, °Brix or titratable acidity were observed. Regression modelling was used to investigate the main effects of amplitude level and treatment time. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R²). Model predictions for critical quality parameters of Hunter colour values (L∗, a∗ and b∗), ascorbic acid and yeast inactivation were closely correlated with the experimental results obtained.     

Modelling the effect of water immersion thermal processing on polyacetylene levels and instrumental colour of carrot disks

C₁₇ polyacetylenes are a group of bioactive compounds present in carrots which have recently gained scientific attention due to their cytotoxicity against cancer cells. In common with many bioactive compounds, their levels may be influenced by thermal processes, such as boiling or water immersion. This study investigated the effect of a number of water immersion time/temperature combinations on concentrations of these compounds and attempted to model the changes. Carrot samples were thermally treated by heating in water at temperatures from 50–100 °C and holding times of 2–60 min. Following heating, levels of falcarinol (FaOH), falcarindiol (FaDOH), falcarindiol-3-acetate (FaDOAc) and Hunter colour parameters (L^∗, a^∗, b^∗) were determined. FaOH, FaDOH, FaDOAc levels were significantly reduced at lower temperatures (50–60 °C). In contrast, samples heated at temperatures from 70–100 °C exhibited higher levels of polyacetylenes (p < 0.05) than did raw unprocessed samples. Regression modelling was used to model the effects of temperature and holding time on the levels of the variables measured. Temperature treatment and holding time were found to significantly affect the polyacetylene content of carrot disks. Predicted models were found to be significant (p < 0.05) with high coefficients of determination (R²).     

Amaranthus hypochondriacus and Amaranthus caudatus germplasm: Characteristics of plants,grain and flours

In the present study, the plant, grain and flour characteristics of 48 Amaranthus hypochondriacus and 11 Amaranthus caudatus lines are reported. A. hypochondriacus grains had a higher thousand kernel weight (0.62–0.88 g), a creamish yellow colour (L∗ = 61.38–68.29, b∗ = 5.26–6.8 and a∗ = 19.71–23.84), whereas A. caudatus grains had a lower thousand kernel weight (0.46–0.70 g) and a reddish-brown colour (L∗ = 47.1–51.2, b∗ = 11.82–14.02 and a∗ = 7.72–13.29). The A. caudatus lines had a higher protein content, fat content and tendency for retrogradation, and lower α-amylase activity as compared to A. hypochondriacus lines. The Amaranthus lines with higher a∗-values and lower thousand kernel weight, L∗- and b∗-values, had a higher fat, crude fibre and protein content. The correlation of fat and crude fibre content with the thousand kernel weight, L∗-, a∗- and b∗-values, was significant. The A. hypochondriacus lines showed higher pasting temperature, and lower peak viscosity, breakdown and setback, as compared to the A. caudatus lines. The result reflected that the lines with higher α-amylase activity showed a lower peak viscosity, breakdown, final viscosity and gel hardness, and a higher pasting temperature.     

Quality of nectarine and peach nectars as affected by lye-peeling and storage

This study was focused on nectarine and peach nectars, with the aim to evaluate different quality indices at the time of production and to devise a predictive model for quality variation during storage at 23 and 37 °C. Nectars were produced from the Elegant Lady and Redhaven peach varieties and from the Stark Red Gold nectarine variety, from both peeled and unpeeled fruits. The effects of processing on antioxidant contents, antioxidant activity and colour were evaluated. At the time of production, β-carotene ranged from 0.52 to 0.79 mg/kg, hydroxycinnamic acids (chlorogenic and neochlorogenic) from 34 to 73 mg/kg, catechin from 0 to 24 mg/kg, quercetin 3-O-glycosides from 3.9 to 12.7 mg/kg, and cyanidin 3-O-glucoside from 0 to 9.4 mg/kg. Within the same variety, carotenoid and phenolic contents were lower in the nectars obtained from peeled fruits than in those obtained from unpeeled fruits. However, as ascorbic acid was adjusted to a level of 300 mg/kg during blending, which is far higher than the observed levels of phenolics and carotenoids, it mainly accounted for nectar radical-scavenging activity towards the 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl radical, which on average was 1.8 mmoles Trolox equivalents/kg. The colour of nectars was improved by processing lye-peeled fruits at room temperature, whatever the variety used; i.e., this process decreased the redness index, a^∗, and increased the lightness index, L^∗, and yellowness index, b^∗, with respect to the traditional process.     

Composition and antioxidant and antimicrobial activity of the essential oil and extracts of Stachys inflata Benth from Iran

Composition and antioxidant and antimicrobial activities of essential oil and methanol extract polar and nonpolar subfractions of Stachys inflata were determined. GC and GC/MS analyse of the essential oil showed 45 constituents representing 95.46% of the oil, the major components linalool (28.55%), α-terpineol (9.45%), spathulenol (8.37%) and (2E)-hexenal (4.62%) constituted 50.99% of it. Essential oil and extracts were also tested for their antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene/linoleic acid assays. In the DPPH test, IC₅₀ value for the polar subfraction was 89.50 μg/ml, indicating an antioxidant potency of about 22% of that of butylated hydroxytoluene (IC₅₀ = 19.72 μg/ml) for this extract. In β-carotene/linoleic acid assay, the best inhibition belonged to the nonpolar subfraction (77.08%). Total phenolic content of the polar and nonpolar extract subfractions was 5.4 and 2.8% (w/w), respectively. The plant also showed a week antimicrobial activity against three strains of tested microorganisms. Linalool and α-terpineol were also tested as major components of the oil and showed no antioxidant but considerable antimicrobial activities.     

Changes in the carotenoid concentration in human postprandial chylomicron and antioxidant effect in HepG2 caused by differently processed fruit and vegetable soups

Ten subjects consumed one serving of an optimised or a reference soup produced using modified or traditional processing methods, respectively. Both soups contained the same proportions of carrot, tomato and broccoli, but with 5% olive oil in the optimised soup and 2.5% in the reference soup. The β-carotene content in 600 mL of the optimised/reference soups was 4.10/2.90 mg, and the lycopene content was 3.90/2.71 mg. The β-carotene and lycopene concentrations in chylomicrons isolated from blood serum samples were similar for both groups. Only 50% of subjects could be considered as carotenoid responders and, in agreement with in vitro accessibility data, the β-carotene concentration in the chylomicrons of these subjects was significantly higher in the group consuming the optimised soup, while no changes were found for lycopene. Postprandial chylomicrons from the optimised soup group exhibited significantly higher antioxidant activity in HepG2 cells than the other group. The stimulation of HepG2 cells by human postprandial chylomicrons seems useful for evaluating the antioxidant effect of different food matrices.     

Characterisation,extraction efficiency,stability and antioxidant activity of phytonutrients in Angelica keiskei

Phytonutrients in Angelica keiskei, a dark green leafy vegetable, were characterised and their extraction efficiency by different compositions of water/ethanol as well as stability at different temperatures was determined. A range in the content of lutein (205–265 mg/kg dry wt), trans-β-carotene (103–130 mg/kg dry wt), and total phenols (8.6–9.7 g/kg) was observed amongst Angelica keiskei grown in three different conditions. LC-ESI-MS/MS analysis identified chlorogenic acid, chalcones and the glucosides of luteolin and quercetin as the major phenolic compounds in Angelica keiskei. Only 46% of lutein was extracted by 70% of ethanol and no carotenoid was detected in 40% ethanol and 100% water extracts of Angelica keiskei. Major phytonutrients in Angelica keiskei were stable at −80 °C up to 12 months whilst β-carotene was significantly degraded at room temperature and 4 °C within 2 months and lutein at room temperature within 12 months.     

Carrot (Daucus carota L.) peroxidase inactivation,phenolic content and physical changes kinetics due to blanching

The kinetics of peroxidase thermal inactivation, total phenolic content degradation, and colour (CIE L∗a∗b∗) and texture changes were studied in a temperature range of 70–90 °C for carrots (Daucus carota L.).