Degradation Kinetics Of Ascorbic Acid Research Articles

Comparison of energy consumption, color, ascorbic acid and carotenoid degradation in guava (Psidium guajava) pulp during conventional and ohmic heating.

This study aimed to compare the effect of ohmic and conventional heat treatments on red guava pulp, evaluating the effects on pulp color, degradation kinetics of ascorbic acid and carotenoids, together with the thermal efficiency of both treatments. Samples were heated by conventional heating (water bath) and ohmic heating (platinum electrodes) using alternating voltage of 21.2 V/m and average frequency of 60 Hz at temperatures of 60, 70 and 80 °C for 110 min. In general, the ascorbic acid degradation followed a first order kinetics, for both heat treatments, the pulp color showed no significant variation (p < 0.05) according to the type and time of heating applied, whereas the carotenoid content was favored by ohmic heating, at the two lowest temperatures tested. As for the heat transfer process, the ohmic treatment showed an average thermal efficiency of 40.93%, while the conventional heating, 2.62%, proving to be a promising emerging technology for processing viscous foods with suspended particles like fruit pulps.

Multilevel modeling in food science: A case study on heat-induced ascorbic acid degradation kinetics

Characterization of variation of experimental results is achieved by repeating experiments. Frequently, results are averaged before data are analysed but that may not be the best practice because valuable information is then lost. Three other ways to analyze repetitions are: (1) each experiment is analyzed on its own (no pooling of data), (2) all experiments are analyzed together in one go (complete pooling), (3) data are analyzed together while allowing for similarities as well as differences in the result (partial pooling). Multilevel modeling uses partial pooling by partitioning variance over more than one level. Level 1 consists of the measurements themselves; higher levels consist of groups or clusters of measurements (repetitions, experiments at various temperatures, at various pH values, etc.) and parameters are analyzed both at the population and at the group/cluster level.The approach is applied to a case study in which heat-induced isothermal degradation of ascorbic acid was studied with 15 repetitions in an aqueous solution, making it a two-level study. The data were analyzed using averaging and complete pooling, complete pooling without averaging, no-pooling at all, and partial pooling. The kinetic model was established by letting the data decide about the order of the reaction, while this was compared to a model where the order was fixed at 1 (first-order model). Results show that both averaging with complete pooling, as well as complete pooling without averaging, strongly underestimate variation. The no-pooling technique overestimates variation, while partial pooling partitions variation over the levels and thus gives a better impression of the variation involved. The kinetics of ascorbic acid appear to be subject to strong variation when each experiment is considered separately because it is a compound that is very sensitive to all kinds of experimental conditions. With multilevel modeling it appeared to be possible to characterize the uncertainties involved much better than with single level modeling. A Bayesian analysis was performed, in which parameters are allowed to be variable, which is useful because multilevel modeling leads to characterization of variation of parameters. The Bayesian method allows to visualize the posterior distribution of parameters, thereby giving more insight in their behaviour. Also, a Bayesian analysis focuses more strongly on predictive accuracy of models, including multilevel models. The predictive accuracy of 4 models describing the same ascorbic acid data was compared and the multilevel model with reaction order estimated from the data performed by far the best in this regard. The pros and cons of multilevel modeling are discussed and it is concluded that multilevel modeling is to be preferred whenever the data allow to perform such an analysis.

The optimal time-temperature conditions for orange juice microwave−assisted pasteurization

In this work, the inactivation kinetics of pectin methylesterase (PME) and degradation kinetics of ascorbic acid (AA) of batch microwave-assisted pasteurized orange juice were studied, at time-temperature conditions from (70–90) °C between (0 and 180) s. The two-component first-order and the fractional kinetic models were adjusted for PME and AA data, respectively. The microwave treatment was effective for the inactivation of PME with minimal AA retention of 85%. The adjusted kinetics parameters at Tref = 90 °C, for PME were: D1, 90 °C = 0.18 s, D2, 90 °C = 32. 8 s, z1 = 10.6 °C, z2 = 11.8 °C, with α = 0.91. For AA were: k90 °C = 0.02 s−1 and z = 55.4 °C with AA∞/AA0 = 0.85. A time-temperature diagram created from the kinetics parameters indicates the best isothermal conditions for orange juice from 78 s at 82.5 °C to 18 s at 90 °C.

KINETICS OF ANTIOXIDANTS DEGRADATION AND QUALITY CHANGES OF CITRON (Citrus medica) FRUIT JUICE CONCENTRATE DURING STORAGE

The aim of the study was to develop fruit juice concentrate from Citron and its kinetic evaluation during storage at 10 ºC, 25 ºC and 40 ºC respectively, for 12th week. The effect of different temperatures on the quality of the juice concentrate was also investigated. The concentration of ascorbic acid in the juice concentrate was monitored after every week of storage. The results showed that degradation kinetics of ascorbic acid during storage was followed by the first-order kinetics. The degradation rates of ascorbic acid during storage at 10 ° C, 25 °C and 40 °C were obtained as 2.27 ± 0.24, 2.46 ± 0.31 and 2.56 ± 0.34 1/week respectively. The higher degradation rate was observed at 40 °C storage temperature. Temperature-dependent rate constants of ascorbic acid of citron juice concentrate was obeyed the Arrhenius relationship with higher R2 values as 0.96. Total antioxidant degradation was also high at higher storage temperatures. The amount of total phenolic content was decreasing at the first few weeks of storage, but later period of storage it was in gradually increasing trend. The storage study demonsrated that ascorbic acid, total polyphenol and antioxidant activity were not degraded at lower temperature after 12th week.

Kinetics of ascorbic acid loss during thermal treatment in different pH buffer solutions and the presence of oxygen

Ascorbic acid stability is greatly influenced by temperature, oxygen content. Both exposures to oxygen and prolonged heating in the presence of oxygen destroy ascorbic acid. Thermal degradation kinetics of ascorbic acid in sodium acetate buffer (0.2 M, pH 5.0) and sodium phosphate buffer (0.1 M, pH 7.0) were studied at the temperature range of 80 to 100°C and the different molar ratio between oxygen and ascorbic acid. The obtained results showed that the decrease in AA concentration as a function of time at constant temperature occurred in two phases. The biphasic model was used to describe the loss of AA in aqueous solution due to thermal treatment. The AA degradation had occurred during thermal processing probably due to oxidation (aerobic degradation). When the oxygen was totally used up, the anaerobic degradation dominated and took place much more slowly than aerobic degradation. At low AA concentration (≈0.28 mM) and an oxygen concentration of 0.25 mM, most of the degradation of AA occurred under aerobic conditions, however, AA was further degraded through an anaerobic pathway at a higher ratio of AA to oxygen concentration [0.57:0.25 (mM:mM) and 1.42:0.25 (mM:mM)]. The estimated activated energy Ea values, the temperature sensitivity of the kvalues was lower at pH 7.0 than at pH 5.0. Studying the degradation of ascorbic in a model system is essential in order to fully understood and applied effectively in food products processing.

Kırmızıbiber (Capsicum annuum L.) Dilimlerinin Vakumla Kurutulması Sırasında Renk ve Askorbik Asidin Bozunma Kinetiği

Red pepper slices were dried in a vacuum dryer at three different temperatures (45, 55 and 65°C) and two absolute pressures (21.5 kPa and 48.0 kPa). Drying temperature and absolute pressure significantly influenced drying time. Degradation kinetics of ascorbic acid in red pepper slices during vacuum drying followed a first-order kinetic model. The highest ascorbic acid retention occurred in the samples dried the combination of 45°C and 21.5 kPa. In addition to the temperature effect, the drying absolute pressure was effective on the loss of ascorbic acid. The activation energy values for ascorbic acid under both absolute pressure of 48.0 kPa and 21.5 kPa were calculated as 70.85 kJ/mol and 81.43 kJ/mol, respectively. The sample surface color degradation after drying was also determined. The color values (Hunter L, a and b) decreased, while ΔE (The color difference) increased during drying. Mathematical modeling of color degradation kinetics indicated that both the zero-order and first-order kinetic model were found to describe the Hunter L, a and b values. However, ΔE followed zero-order kinetic model.

Kajian Kinetika Pengaruh Lama Penyimpanan Terhadap Kadar Vitamin C Pada Buah Apel Malang (Malus Sylvestris)

An analysis for determining kinetics of effect of varied shelf-life time to the level of vitamin C in Malus sylvestris fruits has been conducted. It has used fresh apple Malang (M. sylvestris) from Batu (East Java) at their harvest time with the same size and color as the subject of the research. Therefore, the fruits were stored in room temperature and kept away from direct sunlight for 0, 1, 2, and 3 days. The fruits were extracted by using a juice blending technique with aquadest as the solvent. An iodimetric titration has been used to determine the effect of the varied storage time to the level of vitamin C in the samples. The result shows that the average value of vitamin C level in M. sylvestris stored in 0, 1, 2, and 3 days as much as 2.3904 mg/50g; 2.1073 mg/50g; 2.06695 mg/50g; and 1.9860 mg/50g, respectively. Statistic analysis of ANAVA-A and t-test confirms that there are significant differences between the level of vitamin C of M. sylvestris stored in 0, 1, 2, and 3 days. The conclusion about the kinetics of ascorbic acid degradation of M. sylvestris at 27 0C states three expressions as following as: the reaction is a second order reaction, the constants of reaction rate is 2.65 x 10-2 L(mol.days)-1, the half life is 15.786 days, and kinetics model for the reaction is C = (0.0265t + 1/C0)-1.

Stability of color, β‐carotene, and ascorbic acid in thermally pasteurized carrot puree to the storage temperature and gas barrier properties of selected packaging films

AbstractQuality of pasteurized products can be affected by the combination of temperature abuse and gas barrier properties, especially oxygen transmission rate (OTR), of packaging films. Carrot puree was thermally pasteurized (90 °C, 14 min) and stored in three different types of pouches (OTR—0.99 ± 0.05 [F‐1], 29.8 ± 1.38 [F‐30], and 80.9 ± 2.15 [F‐81] cm3 m−2 day−1) at different temperatures (4, 8, and 13 °C). Weight loss, pH, instrumental color, β‐carotene, and ascorbic acid were evaluated over a 100‐day storage period. Results show that film OTR and temperature had a significant (p &lt; 0.05) effect on food quality and nutritional attributes. High‐barrier film (F‐1) retained quality, while low‐barrier film (F‐81) increased losses during processing and storage for all parameters tested. High‐barrier film demonstrated stable color values (a* and b*) and significantly (p &lt; 0.05) higher retention of β‐carotene during storage period. Ascorbic acid retention varied from 0 to 89%, depending upon packaging type. Based on ascorbic acid degradation kinetics, activation energy and Q10 values ranged from 20.3–72.3 kJ/mol and 1.36–2.96, respectively.Practical applicationsPasteurized food products have limited shelf life under refrigerated conditions. The shelf life of these products can be reduced by the combined effect of temperature abuse and gas barrier properties of packaging films. There is scarce information in the literature focusing on the shelf life studies of in‐pack thermally pasteurized products as a function of gas barrier properties. The selection criteria of films for pasteurized products are complex. Generally, higher the barrier properties needed higher is the cost of packaging. This study demonstrated the suitability of medium‐barrier films for in‐pack pasteurization; and combined effect of temperature abuse and gas barrier properties on the nutrient retention.

Color change, ascorbic acid degradation kinetics, and rehydration behavior of kiwifruit as affected by different drying methods

AbstractIn this study, the drying kinetics, ascorbic acid degradation, and color change kinetics of kiwifruit during hot air drying (HAD), vacuum drying (VD), freeze drying (FD), and hot air–microwave‐assisted vacuum combination drying (HA–MVD) were investigated. The applicability of Weibull model for describing the rehydration kinetics of dried kiwifruits was also assessed. The ascorbic acid content of the kiwi fruit decreased by 77.52, 75.41, 39.86, and 29.64%, and the total phenolic content decreased by 26.62, 29.24, 19.16, and 1.99% after HAD, VD, HA–MVD, and FD, respectively. For all drying processes, the ascorbic acid degradation was best described by the Weibull model. Zero‐order, first‐order, and combined kinetic models were examined to fit data of color parameters (L*, a*, and b*). Scanning electron microscopy images of the dried products were also obtained. The results indicate that HA–MVD may be an alternative method for the drying of kiwifruit since it provides good quality product in shorter time.Practical applicationsKinetic modeling of changes in foods during drying is an important issue in relation to predicting quality changes and setting optimal processing conditions. In this study kinetic models describing the ascorbic acid degradation and also the color change of kiwifruit during four different drying methods were determined. Kiwifruit contains high amount ascorbic acid which is widely considered as a marker of nutritional quality for fruits and vegetables subjected to various drying treatments. That is why it is important to build kinetic models to estimate the degradation rate of ascorbic acid during various drying processes. When the ascorbic acid content, total phenolic content, color, and rehydration properties of the final dried products were compared, it was seen that the hot air–microwave‐assisted vacuum combination drying (HA–MVD) method yielded good quality dried product in quite shorter time as compared to other methods. The results of this study show that the HA–MVD method could be successfully applied for drying of kiwifruits.

Kinetics of inactivation of quality-deteriorating enzymes and degradation of selective phytoconstituents in pink guava pulp during thermal processing.

Thermal inactivation kinetics of peroxidase (POD), polyphenol oxidase (PPO), pectin methyl esterase (PME) and ascorbate oxidase (AO) were studied over the temperature range of 45-85°C along with the degradation kinetics of ascorbic acid (AA) and lycopene in Psidium guajava pulp. POD, PPO, PME and AO followed first-order kinetics whereas AA degradation data was explained by pseudo first-order kinetics. Lycopene degradation was suitably fitted in an exponential model, indicating continuous degradation of lycopene and higher degradation at higher temperature. Activation energy (Ea) of POD, PPO, PME, and AO was 63.79 ± 1.28, 60.36 ± 1.21, 63.22 ± 1.06 and 106.33 ± 8.51kJ/mol, respectively. AA had Ea (95.82 ± 1.92kJ/mol) higher than lycopene (54.92 ± 1.10kJ/mol). PME (Z = 39.4 ± 0.1°C) showed highest heat stability while AO (Z = 14.3 ± 1.1°C) was least stable amongst the enzymes studied. AA (Z = 23.5 ± 0.5°C) was weakest amongst the phytoconstituents in guava pulp and its retention was challenged during thermal processing. The thermal resistance of quality deteriorating enzyme of guava was found to be higher than that of the common spoilage organisms such as Saccharomyces cerevisiae and Lactobacillus plantarum reported for processed fruit products. Thus, this research hints towards the need for more robust thermal processing for inactivation of quality deteriorating enzymes.

THE EFFECT OF TEMPERATURE AND METHOD OF DRYING ON ISOT (URFA PEPPER) AND ITS VITAMIN C DEGRADATION KINETICS

This study investigated drying and vitamin C degradation kinetics in isot (red peppers) at different temperatures (55, 65 and 75°C) and conditions (vacuum and hot air drying). The drying temperature and method had a significant effect on the loss of vitamin C. Vacuum dried samples at 55°C retained the highest quantity of vitamin C, while the samples dried at 75°C in a cabinet dryer lost the highest amount of vitamin C. The results showed that vitamin C is especially sensitive to the presence of oxygen and higher temperatures. The Weibull model was found to provide the mathematical equation best describing the ascorbic acid degradation kinetics in red peppers, while the Page model best reflected the drying kinetics.

Kinetics of ascorbic acid thermal degradation in Valencia orange juices and evaluation of its shelf life

Ascorbic acid is a well-known natural antioxidant which is widely distributed in nature, especially in green plants. Its traditionally known sources are citrus fruits like orange. This vitamin acts as an efficient radical inhibitor and it has been used as a food additive. Moreover, it presents antioxidant activity and contributes for the prevention of certain types of cancer. Ascorbic acid is also used as an index of nutritional quality of fruits and vegetables, due to its sensibility to different kinds of degradation in food processing and subsequent storage. Thus, the study of ascorbic acid degradation kinetics is important to raise information that allows estimating the quality changes that occur during the storage of food products. The purpose of this research was to evaluate the thermal degradation kinetics of ascorbic acid in Valencia orange juices and to quantify the effect of water activity on its rate of loss upon storage. Ascorbic acid content was determined by titration with 2,6 dichlorophenol indophenol. Its degradation as a function of storage time was studied at different temperatures during a period of 14 days of storage. Reaction constant rates (k) and the order of reaction (n) were determined through regression analysis of experimental data. Higher coefficient of determination (R2) indicated that a first-order reaction model fits closely well to data obtained in this study. In general, it was observed that increasing temperature and water activity led to increasing losses of ascorbic acid. A direct equation for the estimation of the shelf life of the juice with respect to ascorbic acid losses at any specified temperature and degradation rate has been derived.

Effects of high-humidity hot air impingement blanching (HHAIB) pretreatment on the change of antioxidant capacity, the degradation kinetics of red pigment, ascorbic acid in dehydrated red peppers during storage

Effect of high-humidity hot air impingement blanching on photochemical degradation kinetics (red pigments and ascorbic acid) and antioxidant capacity changes (2,2-diphenyl-1-picrylhydracyl, DPPH and total antioxidant capacity) of red pepper during 6-month storage at ambient temperature in dark was investigated. Ultrastructure of raw and blanched samples was also observed using a transmission electron microscope (TEM). Blanching followed by drying resulted in 63–85% and 33–59% reduction in red pigment and ascorbic acid content, respectively. The antioxidant capacity of samples was found to increase after drying. After 6-month storage, further breakdown of red pigment and ascorbic acid was observed. The red pigment degradation followed the first-order reaction kinetics; untreated samples displayed the most red pigment loss, while the Weibull model described well the ascorbic acid degradation kinetics. Ultrastructure observations explained why over-blanching can cause serious phytochemical degradation. The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage.

Degradation kinetics of ascorbic acid in home-made juices.

Degradation kinetics of ascorbic acid in home-made juices.

Modeling the degradation kinetics of ascorbic acid

ABSTRACTMost published reports on ascorbic acid (AA) degradation during food storage and heat preservation suggest that it follows first-order kinetics. Deviations from this pattern include Weibullian decay, and exponential drop approaching finite nonzero retention. Almost invariably, the degradation rate constant's temperature-dependence followed the Arrhenius equation, and hence the simpler exponential model too. A formula and freely downloadable interactive Wolfram Demonstration to convert the Arrhenius model's energy of activation, Ea, to the exponential model's c parameter, or vice versa, are provided. The AA's isothermal and non-isothermal degradation can be simulated with freely downloadable interactive Wolfram Demonstrations in which the model's parameters can be entered and modified by moving sliders on the screen. Where the degradation is known a priori to follow first or other fixed order kinetics, one can use the endpoints method, and in principle the successive points method too, to estimate the reaction's kinetic parameters from considerably fewer AA concentration determinations than in the traditional manner. Freeware to do the calculations by either method has been recently made available on the Internet. Once obtained in this way, the kinetic parameters can be used to reconstruct the entire degradation curves and predict those at different temperature profiles, isothermal or dynamic. Comparison of the predicted concentration ratios with experimental ones offers a way to validate or refute the kinetic model and the assumptions on which it is based.

Degradation kinetics of ascorbic acid in encapsulated spray-dried honey powder packaged in aluminium laminated polyethylene and high-density polyethylene

ABSTRACTThe present study evaluated the stability of nutritionally rich encapsulated spray-dried honey powders in terms of hygroscopicity, glass transition temperature, total phenolic content, antioxidant activity and ascorbic acid using maltodextrin, gum arabic, and whey protein concentrate as carriers during a storage period of 180 days using high-density polyethylene and aluminium laminated polyethylene as packaging materials at 25°C (room temperature) and 35°C (accelerated temperature). The results revealed that temperature caused a negative influence on the glass transition temperature and stability of ascorbic acid. The kinetics of ascorbic acid degradation followed a first-order reaction with a reaction rate constant dependent on temperature and packaging material. Honey powder developed with whey protein concentrate as carrier agent and stored in aluminium laminated polyethylene pouches at 35°C possessed the highest antioxidant activity and ascorbic acid due to the presence of phenolic compounds in honey, aonla (Emblica officinalis. Gaertn), and basil (Ocimum sanctum) extract. The honey powders stored in aluminium laminated polyethylene pouches showed comparatively better antioxidant properties (total phenolic content, ascorbic acid, and antioxidant activity) and minimum hygroscopicity than the powders stored in high-density polyethylene at both the storage temperatures.

Nutritional Properties of Ready-to-Eat Pasta Salads: Effect of Processing and Storage Conditions

Nutritional properties of ready-to-eat meals can vary greatly during storage due to the complexity of their food matrix. The nutritional properties of two types of ready-to-eat pasta salads differing in the processing of one of their ingredients (bell pepper) were evaluated during 12 days of storage at 4 and 12C. Salads with cooked (C) or uncooked (UC) red bell pepper were analyzed for proximate composition, dietary fiber content, lipid profile, ascorbic acid degradation kinetics and in vitro digestion of starch; rapid digestible starch and predicted glycemic index were also calculated. Results showed that vegetable processing significantly affected the ascorbic acid degradation, starch hydrolysis, as well as the fat and energy content of the salads. Nutritional properties of commercially available ready-to-eat pasta salads may significantly differ between manufacturers depending on the processing applied, storage temperature and time after production, and thus this should be seriously considered when evaluating their health implications. Practical Applications Despite the convenience and ease of preparation of ready-to-eat meals, consumers should be aware that health benefits claimed by some ingredients included in these products might be lessened by the storage conditions (time and temperature), type of processing and interaction with other constituents of the product. This work provides food manufacturers with an in depth insight on how these factors can affect the nutritional properties of their products and lead to foods that can retain the full potential of their nutritional qualities. More research regarding the health implications of the consumption of ready-to-eat foods is encouraged.

Influence of temperature, voltage gradient and electrode on ascorbic acid degradation kinetics during ohmic heating of tropical fruit pulp

Vitamin C also known as ascorbic acid is one of the most heat sensitive vitamins. Tropical fruits are a good source of vitamin C, but this vitamin is lost during processing due to high temperature. Ohmic heating is attempted as an alternative technique for the preservation of tropical fruit pulp. The objective of this study was to evaluate the influence of change in temperature, voltage gradient and electrode on vitamin C degradation in the tropical fruit pulps including papaya, sapota and guava, when it is ohmically heated. It was observed that with increase in temperature and voltage gradient, the ascorbic acid content decreased of all the fruit pulp test. Ohmic heating experiment was conducted with two different electrode viz stainless steel and titanium electrode. Ohmic heating experiment when performed with titanium electrode showed better retention of ascorbic acid. A separate experiment was conducted to study the effect of ohmic time on ascorbic acid degradation. Ascorbic acid degradation is also studied during the storage of the ohmic heated pulp. Ascorbic acid content decreased with increase in ohmic heating time and also with increase in storage days.

Kinetics of Ascorbic Acid Degradation and Quality Changes in Guava Juice during Refrigerated Storage

In this study, the kinetics of ascorbic acid degradation and quality changes in guava juice during refrigerated storage at various temperatures were investigated The ascorbic acid degradation in all juice samples during refrigerated storage was fitted in first-order reaction with high regression coefficient (r2≈0.961-0.999). Lowest rate constant (k) was obtained in all juice samples stored at 5°C (3.0-5.8 × 10-2 day-1), followed by 10°C (3.8-7.1 × 10-2 day-1) and 15°C (5.2-9.1 × 10-2 day-1). Accordingly, the half-life (t1/2) values of ascorbic acid were longer when juice samples stored at lower temperature. The estimated activation energy (Ea) of ascorbic degradation was in the range of 0.443-0.544 kcal/mol for 30-100% juice samples. Quality attributes of juice samples stored at various refrigerated temperature for 21 days did not showed any significant difference (p>0.05) in pH (3.80-3.83), acidity (0.25-0.29%), and total soluble solids (12.00-12.20 °Brix). Microbial populations were below the detection limit during the whole storage period.

ASCORBIC ACID DEGRADATION KINETIC FOR MICROWAVE DRIED BASIL, PURSLANE AND CELERY LEAVES

In this study, the goal was to evaluate the ascorbic acid degradation in basil, purslane and celery leaves during microwave drying. The effects of microwave output power and sample amount on ascorbic acid loss in basil, purslane and celery leaves were investigated. The method for the determination of ascorbic acid content was based on the reaction between ascorbic acid and 2,6-dichloroindophenol and was successfully applied to basil, purslane and celery leaves. Increasing microwave output power and decreasing sample amount led to higher degradation rates in basil, purslane and celery leaves. Ascorbic acid degradation kinetics in basil, purslane and celery leaves during microwave drying followed a first-order reaction. The activation energy values were also calculated using an exponential expression based on Arrhenius equation for degradation of ascorbic acid.