-
[show abstract]
[hide abstract]
ABSTRACT: The effect of thermal processing (85-130°C) and combined thermal/high pressure processing (100°C combined with 0.1 to 700MPa and 700MPa combined with 85-115°C) on β-carotene isomerisation in an olive oil/carrot emulsion and pure olive oil phase enriched with carrot β-carotene was investigated. Thermal processing always resulted in an increase in the contribution of the cis-isomers, with the increase being more pronounced at higher temperatures. In the oil/carrot emulsion, less β-carotene isomerisation was observed during combined thermal/high pressure processing compared to thermal processing. This effect was attributed to strengthening of the carrot cell walls under high pressure, thereby hindering the transfer of β-carotene to the oil phase and lowering its susceptibility to isomerisation. In an oil phase enriched with β-carotene, β-carotene isomerisation was not influenced by the applied pressure at 100°C and became almost temperature insensitive at 700MPa.
Food Chemistry 06/2013; 138(2-3):1515-20. · 3.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the present study, the effect of equivalent thermal and high pressure processes at pasteurization and sterilization intensities on some health related properties of high pressure homogenized tomato puree containing oil were investigated. Total lycopene concentration, cis-lycopene content and in vitro lycopene bioaccessibility were examined as health related properties. Results showed that pasteurization hardly affected the health related properties of tomato puree. Only the formation of cis-lycopene during intense thermal pasteurization was observed. Sterilization processes on the other hand had a significant effect on the health related properties. A significant decrease in total lycopene concentration was found after the sterilization processes. Next to degradation, significant isomerization was also observed: all-trans-lycopene was mainly converted to 9-cis- and 13-cis-lycopene. High pressure sterilization limited the overall lycopene isomerization, when compared to the equivalent thermal sterilization processes. The formation of 5-cis-lycopene on the other hand seemed to be favoured by high pressure. The in vitro lycopene bioaccessibility of high pressure homogenized tomato puree containing oil was decreased during subsequent thermal or high pressure processing, whereby significant changes were observed for all the sterilization processes.
Food Chemistry 12/2012; 135(3):1290-7. · 3.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To study the effect of particle size on the relative all-E-β-carotene and all-E-lycopene bioaccessibility in carrot- and tomato-derived suspensions, respectively, an in vitro digestion approach including oil was used. Adding olive oil (2%) during digestion, especially as an oil-in-water emulsion, resulted in a substantial increase in carotenoid uptake in the micellar phase. Carotenoid bioaccessibility decreased with average particle size. Only particles smaller than an individual cell resulted in high bioaccessibility values, pointing out the importance of the cell wall as main barrier for carotenoid uptake. The relation obtained between particle size and bioaccessibility was used to predict the carotenoid bioaccessibility in carrot- and tomato-derived purées. These predictions indicated that carotenoid bioaccessibility in plant-based food suspensions is not only determined by the cell wall integrity (related with particle size), but is also affected by interactions between the structural compounds of the complex food matrix.
Journal of Agricultural and Food Chemistry 11/2012; · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: As a rule, previous studies have generally addressed the comparison of novel and traditional processing technologies by a targeted approach, in the sense that only the impact on specific quality attributes is investigated. By contrast, this work focused on an untargeted strategy, in order to take into account unexpected and unintended effects of (novel) processing, and to possibly uncover unknown compounds resulting from alternative processing. The potential of headspace GC-MS fingerprinting was explored as a tool to compare the impact of thermal, high pressure (HP) and pulsed electric field (PEF) processing for mild pasteurisation of orange juice. This study demonstrated that when processing conditions are selected based on equivalent microbial safety, the impact of heat, HP and PEF pasteurisation on the volatile profile of orange juice can be considered comparable. During refrigerated storage, however, indirect impact differences were revealed, which were attributed to differences in degree of enzyme inactivation.
Food Chemistry 10/2012; 134(4):2303-12. · 3.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The firmness of green bell pepper (Capsicum annuum) was studied under different processing conditions. Thermal texture degradation kinetics of pepper tissue between 75 and
95°C could be accurately described by a fractional conversion model. The firmness of pre-processed pepper increased when
the samples were submitted to several heat, pressure, and combinations of heat/pressure and calcium soaking pre-treatments.
Pre-heating at 55°C during 60min and mild heat/high-pressure treatments (200MPa at 25°C, 15min) yielded the best results,
which were further improved when combined with calcium soaking. These pre-treatments significantly slowed down thermal texture
degradation of pepper at 90°C, a typical temperature used for pepper blanching prior to freezing. The above-mentioned pre-treated
samples showed a significant reduction in firmness when frozen by regular freezing at 0.1MPa. The same samples showed no
changes in firmness when frozen by high-pressure shift freezing at 200MPa. When freezing was carried out by high-pressure
shift and after frozen storage (−18°C) for 2.5 months, pressure pre-treated pepper showed a better retention of texture than
thermal pre-treated pepper.
European Food Research and Technology 04/2012; 226(1):33-43. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The combined isothermal (10–60°C) and isobaric (0.1–650MPa) inactivation kinetics of lipoxygenase (LOX) extracted from tomatoes
and reconstituted in a tomato purée were studied. Thermal inactivation of LOX at atmospheric pressure proceeded in the temperature
range of 45–65°C. LOX inactivation did not follow first order kinetics; the data could be fitted assuming that the two isoforms
of LOX with different thermostability were present. Combined thermal and high pressure inactivation occurs at pressures in
the range of 100–650MPa combined with temperatures from 10–60°C, and followed first-order kinetics. In the high-temperature/low-pressure
range, (T≥50°C and P≤300MPa) an antagonistic effect is observed, therefore, the Arrhenius and Eyring equation cannot be used over the entire
temperature and pressure range. Small temperature dependence is found in the low-temperature/high pressure range. A third
degree polynomial model was successfully applied to describe the temperature–pressure dependence of the inactivation rate
constants, which can be useful to predict inactivation rate constants of tomato LOX reconstituted in tomato purée in the temperature–pressure
range studied.
European Food Research and Technology 04/2012; 222(5):636-642. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Thermal texture evolution kinetics (90–110°C) of nonpretreated and high-pressure pretreated (HP=400MPa, 60°C, 15min)
carrots were determined using a multiparameter approach (cutting, compression). Alcohol Insoluble Residues (AIR) were extracted
before and after thermal processing of the samples and the degree of methylation (DM) was estimated. The β-elimination kinetics
of the water soluble pectin extract from the AIR was studied and related to the changes in material properties. Morphological
changes and tissue-failure characteristics were monitored. The mechanical properties were strongly dependent on the processing
temperature and the DM of the samples. Texture degradation rate constants were independent of the texture measurement method.
Increasing temperature accelerated the β-elimination reaction (k
b) and the thermosoftening (k
x) rates, but pretreatment condition slowed down the rates. Interestingly, a strong correlation (r>0.99) between k
b and k
x occurred. Thermal processing resulted in cell-wall thickening accompanied by a transition from cell rupture to cell separation,
a process retarded by pretreatment condition.
European Food Research and Technology 04/2012; 226(1):127-135. · 1.57 Impact Factor
-
Trends in Food Science & Technology 04/2012; 24(2):103-118. · 3.67 Impact Factor
-
Food Hydrocolloids 01/2012; 26(1):89-98. · 3.47 Impact Factor
-
Food Hydrocolloids. 01/2012; 26(1):89-98.
-
[show abstract]
[hide abstract]
ABSTRACT: The effect of particle properties of carrot suspensions on their rheological behaviour was investigated. Hereto, a range of carrot suspensions, with varying particle size (~73, 176, 262 and 369 µm) and concentration (30-65 w%), was prepared by the reconstitution of particles of carrot material in water. Suspensions with average particle size of ~73 µm consisted of cell fragments whereas suspensions with larger particle sizes contained mainly cell clusters of which the cell number increased with increasing particle size. The rheological characteristics showed that the carrot suspensions have a non-Newtonian behaviour (shear thinning or thickening, depending on particle concentration, size and morphology). The network structure of all suspensions could be described as a weak gel. Increase in yield stress and storage modulus with particle concentration could be fitted to a power law model. Particle concentration, size and morphology appeared to be key structural parameters controlling the rheology of these carrot suspensions. When comparing the rheological behaviour of the reconstituted suspensions with the original carrot purée of similar average diameter and pulp content, the network structure (measured as yield stress or storage modulus) in carrot purée was weaker due to the broader particle size distribution.
Food and Bioprocess Technology 01/2012; · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The influence of the degree and pattern of methylesterification (DM and PM, respectively) on the stiffness of Ca(2+)-pectin gels is extensively examined, at various Ca(2+) concentrations. Accordingly, a highly methyl-esterified pectin was selectively de-esterified using NaOH, plant or fungal pectin methylesterase in order to produce series of pectins with varied pattern and broad ranges of methylesterification. The PM was quantified as absolute degree of blockiness (DB(abs)). Ca(2+)-pectin gels were prepared at various Ca(2+) concentrations. Gel stiffness (G' at 1rad/s) was determined and mapped out as a function of DM, DB(abs) and Ca(2+) concentration. At low Ca(2+) concentrations, G' depends on polymer's DM and DB(abs). At high Ca(2+) concentrations, a master curve is obtained over a wide range of DM, irrespective of DB(abs). Depending on methylesterification pattern, increase of G' is related not only to an increase in the number of junction zones per pectin chain, but also to an increase in the size of junction zones and the number of dimerised chains occurring in the gels. These results provide a detailed insight into the occurrence of junction zones in Ca(2+)-pectin gels.
Carbohydrate research 11/2011; 348:69-76. · 2.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tomatoes are often processed into shelf-stable products. However, the different processing steps might have an impact on the product quality. In this study, a model tomato soup was prepared and the impact of pilot-scale aseptic processing, including heat treatment and high-pressure homogenization, on some selected quality parameters was evaluated. The vitamin C content, the lycopene isomer content, and the lycopene bioaccessibility were considered as health-promoting attributes. As a structural characteristic, the viscosity of the tomato soup was investigated. A tomato soup without oil as well as a tomato soup containing 5% olive oil were evaluated. Thermal processing had a negative effect on the vitamin C content, while lycopene degradation was limited. For both compounds, high-pressure homogenization caused additional losses. High-pressure homogenization also resulted in a higher viscosity that was accompanied by a decrease in lycopene bioaccessibility. The presence of lipids clearly enhanced the lycopene isomerization susceptibility and improved the bioaccessibility. PRACTICAL APPLICATION: The results obtained in this study are of relevance for product formulation and process design of tomato-based food products.
Journal of Food Science 06/2011; 76(5):C714-23. · 1.66 Impact Factor
-
Food Hydrocolloids 05/2011; 25(3):434-443. · 3.47 Impact Factor
-
Food Hydrocolloids. 05/2011; 25(3):434-443.
-
[show abstract]
[hide abstract]
ABSTRACT: This study describes a detailed and systematic investigation on the effect of thermal processing in terms of temperature and time (kinetic study) on β-carotene in vitro bioaccessibility in carrots. β-Carotene in vitro bioaccessibility increased with increasing processing temperature and time until steady-state conditions were reached after prolonged heating. The bioaccessibility values in steady-state conditions were temperature dependent. The experimental bioaccessibility data could adequately be modeled with a fractional conversion model. For the first time, modeling of processing-induced bioaccessibility changes is reported in literature. The results of the present kinetic study were used to estimate the impact of industrially relevant thermal processes on β-carotene bioaccessibility in carrots by simulation. It was shown that, to achieve a high β-carotene bioaccessibility, processing of carrots is essential (i.e., on the one hand, intense thermal processing or, on the other hand, mild thermal processing combined with intense mechanical processing).
Journal of Agricultural and Food Chemistry 03/2011; 59(7):3162-7. · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In order to gain insight into the in situ properties and localisation of kiwi pectin methylesterase inhibitor (PMEI), a toolbox of monoclonal antibodies (MA) towards PMEI was developed. Out of a panel of MA generated towards kiwi PMEI, three MA, i.e. MA-KI9A8, MA-KI15C12 and MA-KI15G7, were selected. Thorough characterisation proved that these MA bind specifically to kiwi PMEI and kiwi PMEI in complex with plant PME and recognise a linear epitope on PMEI. Extract screening of green kiwi (Actinidia deliciosa) and gold kiwi (Actinidia chinensis) confirmed the potential use of these MA as probes to screen for PMEI in other sources. Tissue printing revealed the overall presence of PMEI in pericarp and columella of ripe kiwi fruit. Further analysis on the cellular level showed PMEI label concentrated in the middle lamella and in the cell-wall region near the plasmalemma. Intercellular spaces, however, were either completely filled or lined with label. In conclusion, the developed toolbox of antibodies towards PMEI can be used as probes to localise PMEI on different levels, which can be of relevance for plant physiologists as well as food technologists.
Planta 11/2010; 233(2):287-98. · 3.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effect of high pressure-high temperature (HPHT) processing on the formation of acrylamide and other Maillard-type reaction compounds was investigated in order to elucidate the impact of HPHT conditions on the different stages of the Maillard reaction. This study was performed in equimolar asparagine-glucose model systems that were treated at various HP/HT conditions (100-115 °C, 400-700 MPa, 0-60 min), and, for comparison, the model system was also heat-treated at ambient pressure. On the treated samples, the concentration of acrylamide, reactants, hydroxymethylfurfural, organic acids, and melanoidins was determined and the pH prior to and after treatment was measured. Based on the measured responses, the retarding effect of high pressure on the overall Maillard reaction was demonstrated; no or little differences were observed between 400 and 700 MPa. The study was conducted in two types of buffer, i.e. phosphate and MES buffer. In case of acrylamide, aspartic acid and browning, a higher concentration was generated in the MES buffer system, but these differences with the phosphate buffer system could be ascribed to pH changes resulting from the application of combined high pressure and high temperature. Based on the results, acrylamide formation is not expected to pose a major hazard to HPHT-treated products.
Journal of Agricultural and Food Chemistry 10/2010; 58(22):11740-8. · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The thermal stability of vitamin C (including l-ascorbic acid [l-AA] and dehydroascorbic acid [DHAA]) in crushed broccoli was evaluated in the temperature range of 30 to 90 degrees C whereas that of ascorbic acid oxidase (AAO) was evaluated in the temperature range of 20 to 95 degrees C. Thermal treatments (for 15 min) of crushed broccoli at 30 to 60 degrees C resulted in conversion of l-AA to DHAA whereas treatments at 70 to 90 degrees C retained vitamin C as l-AA. These observations indicated that enzymes (for example, AAO) could play a major role in the initial phase (that is, oxidation of l-AA to DHAA) of vitamin C degradation in broccoli. Consequently, a study to evaluate the temperature-time conditions that could result in AAO inactivation in broccoli was carried out. In this study, higher AAO activity was observed in broccoli florets than stalks. During thermal treatments for 10 min, AAO in broccoli florets and stalks was stable until around 50 degrees C. A 10-min thermal treatment at 80 degrees C almost completely inactivated AAO in broccoli. AAO inactivation followed 1st order kinetics in the temperature range of 55 to 65 degrees C. Based on this study, a thermal treatment above 70 degrees C is recommended for crushed vegetable products to prevent oxidation of l-AA to DHAA, the onset of vitamin C degradation. PRACTICAL APPLICATION: The results reported in this study are applicable for both domestic and industrial processing of vegetables into products such as juices, soups, and purees. In this report, we have demonstrated that processing crushed broccoli in a temperature range of 30 to 60 degrees C could result in the conversion of l-ascorbic acid to dehydroascorbic (DHAA), a very important reaction in regard to vitamin C degradation because DHAA could be easily converted to other compounds that do not have the biological activity of vitamin C.
Journal of Food Science 05/2010; 75(4):C336-40. · 1.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Pectin is abundantly used in the food industry. In jams and jellies, confectionary products and bakery fillings, it is applied as a gelling agent. The characteristics of the final gel depend on many factors, especially the food system composition (e.g. pectin concentration, pH, soluble solids) and the chemical fine structure of pectin. Detailed insight into how these variables affect gel properties allows fine-tuning of gel characteristics in order to meet the functionality required for each individual food application. This review focuses specifically on pectin–calcium gels.
Trends in Food Science & Technology 05/2010; 21(5):219-228. · 3.67 Impact Factor
