Rate Of Ascorbic Acid Degradation Research Articles

Hyphenated study on drying kinetics and ascorbic acid degradation of guava (Psidium guajava L.) fruit

AbstractIn this study, insights into the effect of process parameters (temperature: 55, 60 and 65°C; thickness: 3, 5, and 8 mm; time: up to 5 hr) on drying (mechanical, solar) kinetics and sorption behavior of guava fruits (variety: local and hybrid) with a focus on the degradation of ascorbic acid (AA) were established for the first time to the best of existing knowledge. The experimental results showed the highest moisture diffusion coefficient and lower activation energy (Ea) of 0.000326 cm2/s and 9.62 kcal/g.mole, respectively for hybrid mature guava variety; whereas, the highest AA degradation rate (0.107 mg AA/hr) with lower Ea (4.3 kcal/g.mole) was obtained for local mature guava variety. Besides, a mixed‐mode solar dryer assisted with a fan seemed to be efficient for drying guava fruit in comparison to drying under direct sunlight. In terms of sorption behavior, both local and hybrid guava followed sigmoidal (type II) shape isotherm where the experimental data were well fitted with Brunauer–Emmett–Teller (BET) model.Practical applicationThe drying conditions to have dried guava (Psidium guajava L.) fruit with high ascorbic acid (AA) were investigated. The mathematical model was successfully applied to describe the drying kinetics and degradation of AA of guava fruit. Process parameters and methods influencing drying kinetics and AA degradation rate were detailed. BET model fits well to describe the sorption isotherms of dried guava fruit, in understanding its storage behavior. The information of this study would help in the drying process optimization of guava fruit, in order to make them available in the off‐seasons.

Influence of pH and Composition on Nonenzymatic Browning of Shelf-Stable Orange Juice during Storage.

Nonenzymatic browning during storage of pasteurized shelf-stable orange juice causes a major color deterioration, which negatively affects consumer acceptance of the juice. This study, for the first time, investigated on a kinetic basis the effect of pH and suspected nonenzymatic browning reaction precursors such as ascorbic acid, fructose, and arginine on nonenzymatic browning during accelerated storage (42 °C) using an orange-juice-based model system. The results showed that lowering the pH of the model juice system from 3.8 to 1.5 significantly increased the rate of ascorbic acid degradation, the rate changes (increases and decreases) in different sugars, and the rates of furfural and 5-hydroxymethylfurfural formation. These changes coincided with a higher browning intensity, which became more pronounced toward the end of storage of the juice model system. Similarly, adding more ascorbic acid and fructose largely increased the formation of furfural and 5-hydroxymethylfurfural, respectively, and resulted in a higher browning intensity. In conclusion, lowering the pH of the orange juice or addition of ascorbic acid or fructose will enhance its browning during prolonged storage.

Effect of Cooking Methods on Ascorbic Acid Destruction of Green Leafy Vegetables

Ascorbic acid is highly sensitive vitamin to various modes of cooking processes. Ethiopian green collards (Brassica carinata), locally called Ye’abesha Gomen, and cabbage (Brassica oleracea) are important green vegetables for ascorbic acid source in the country. The rate of ascorbic acid degradation in cabbage and Ethiopian green collard was studied employing two processing methods: open-pan and pressure cooking which are highly customized in household cooking. Samples were cooked at 5, 10, 15, 20, 25, 30, and 35 min under each processing method. Ascorbic acid concentration in each sample was determined by using a spectrophotometer at 520 nm wavelength using the standard plot of pure ascorbic acid solution. The initial concentration of ascorbic acid in fresh cabbage and Ethiopian green collard were found to be 33.76 ± 0.58 and 38.14 ± 0.19 mg/100 g, respectively. Well-cooked and edible Ethiopian green collard was obtained at 10 minutes of cooking time by pressure cooking with ascorbic acid retention of 31.8% from its initial contents. However, a cooking time of 25 min was required by the open-pan cooking method with 26.8% ascorbic acid retention. Edible cabbage was attained at 10 and 20 minutes of cooking time by pressure and open-pan cooking methods maintaining 36.9 and 30.9% of ascorbic acid, respectively. Thus, the pressure cooking method required short cooking time for having well-cooked and edible green leafy vegetable with better ascorbic acid retention. The outputs of this work would be helpful to design and control practical thermal processing situations and to minimize the loss of ascorbic acid in green leafy vegetables.

English

This work was aimed at investigating the effect of storage temperature on the physicochemical, nutritional, and microbial quality of soursop juice. Physicochemical quality was determined by measuring changes in pH, titratable acidity, total soluble solids and colour (L*a*b* values). Ascorbic acid levels, total phenolic content and total antioxidant capacity were analysed to determine the effect of storage temperature on nutritional quality. The changes in aerobic mesophilic and psychrophilic bacteria, lactic acid bacteria, Enterobacteriaceae, as well as yeast and moulds were enumerated to determine the effect of storage temperature on microbial quality. Soursop juice was pasteurised at 85°C for 5 min and stored at varying temperatures of 4, 10 and 25°C. Storage was carried out for 12 weeks at both 4 and 10°C, while at 25°C the juice was stored for 3.5 weeks when visible signs of spoilage was detected. Storing soursop juice at 4oC did not affect quality, however, at 25°C, decreases in pH and total soluble solids with an increase in titratable acidity was observed. In addition, a faster rate of ascorbic acid degradation was observed at 25°C. The main group of microorganisms that were responsible for the spoilage of soursop juice stored at 25°C were lactic acid bacteria, and yeasts and moulds. The results of this work show that pasteurised soursop juice can be stored at refrigeration temperatures without changes in quality. Key words: Soursop juice, pasteurization, storage temperature, lactic acid bacteria, ascorbic acid.

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.

New active package based on titania coated on cardboard for storage of fresh prepared orange juice

AbstractAn active package from cardboard coated with titanium dioxide was designed for storage of fresh prepared orange juice. The organoleptical changes of the orange juice were statistically significant and revealed the preservation role of the active cardboard at 4 °C. Statistically significant positive effect on the reducing the rate of ascorbic acid degradation and on the increasing the catalase activity, respectively, was generated by coating TiO2, revealing that the semiconductor favors the preservation of the orange juice during storage. FTIR spectra revealed new compounds in the juice stored in the active package at 4 °C, but these substances has no significantly affected the characteristics of the juice. This study reveals that the TiO2‐cardboard is a promising solution to package fresh prepared orange juice and to store it in safety conditions at 4 °C for 7 days. The mechanism that ensure the preservation of juice as a result of TiO2 particles photoactivity was discussed.Practical applicationsThe study report about a new type of active package made from cardboard coated with TiO2 designed for storage of fresh prepared orange juice. The results showed the statistically significant and positive influence of TiO2 on preserving the organoleptical parameters, ascorbic acid content and catalase activity of the orange juice during storage for 9 days. This study reveals that the TiO2‐cardboard is a promising solution to package fresh prepared orange juice and to store it in safety conditions at 4 °C for 7 days.

Thermal assisted high-pressure processing of Indian gooseberry (Embilica officinalis L.) juice – Impact on colour and nutritional attributes

The effect of thermal assisted high-pressure processing (THPP) on the physicochemical properties, bioactive functional compounds and antioxidant capacity of Indian gooseberry juice was investigated within the domain of 200–500 MPa, 1 s-20 min and 30–60 °C. THPP did not significantly (p > 0.05) affect the pH, TSS and titrable acidity of the juice. Lightness (L*) of the juice was increased after processing and about 85% of ascorbic acid (AA) was retained after THPP at the extreme condition. Total antioxidant capacity (TAC) and total phenolic content (TPC) in THPP treated samples increased with an increase in pressure upto 50 °C (20 and 28% respectively); temperature had a major degradation effect on these. Factor analysis revealed that AA content in the juice was the most sensitive response influenced by THPP. The degradation of ascorbic acid in the juice during THPP followed the first-order kinetics. The AA degradation rate (k) ranged from 1.57 × 10−3- 2.013 × 10−3 min−1. Within the studied domain, the activation volume for AA degradation ranged from 1.65 to 2.78 mL mol−1 and the activation energy between 12.5 and 16.4 kJ mol−1. The secondary model was developed for AA rate constant as a function of pressure and temperature within the domain.

Whey acerola-flavoured drink submitted ohmic heating processing: Is there an optimal combination of the operational parameters?

Whey acerola-flavoured drink was treated using ohmic heating (OH) at 65°C for 30min to evaluate different frequencies (10, 100 and 1000Hz with 25V) and voltages (45, 60 and 80V at 60Hz) and by conventional heating (CH) with the same temperature profile (65°C/30min). Rheology parameters, color changes (h°, C∗, ΔE) microstructure (optical microscopy), and ascorbic acid (AA) degradation kinetics were performed. AA degradation rates ranged from 1.7 to 29.3% and from 2.8 to 24.8% for OH and CH, respectively. The beverages treated with both processes exhibited a pseudo-plastic behavior (n<1), higher saturation (C∗), lesser reddish color (h°), and higher color variations (ΔE∗). In microstructure analysis, OH (1000Hz–25V and 80V–60Hz) was able to rupture the cell structure. The best results were observed at low frequencies and voltage OH processes on whey acerola-flavoured drinks should be performed at low frequencies and voltages (≤100Hz and 45V), an alternating current (A/C). However, despite the use of inert electrodes, the existence of corrosion was not evaluated, being an important information to be investigated.

High methoxyl pectin–methyl cellulose films with antioxidant activity at a functional food interface

The effect of using increasing proportions of methylcellulose (MC) for the development of glycerol plasticized films based on high methoxyl pectin (HMP) (30:70, 50:50 and 70:30w/w HMP:MC) and carrying l-(+)-ascorbic acid (AA) was studied with the purpose of achieving higher stability of AA and localized antioxidant activity at food interfaces. MC and 30:70 HMP:MC systems could not be casted. The shelf-life of the other AA-active films was assessed by storage at 25°C, constant relative humidity (RH: 33.3%, 57.7% and 75.2%) and vacuum conditions. The rate constant for AA hydrolysis increased with the RH and, hence, with water mobility. Browning and AA degradation rates were directly related. When stored at 75.2% RH, both decreased as MC proportion increased. Compared to HMP film, the highest proportion of MC (50:50 HMP:MC) showed the highest AA stabilization under vacuum and greater performance under air atmosphere. They also developed localized antioxidant activity preserving the tocopherol content of walnut oil.

Chemical and colour changes related to the use of sorbates and ascorbic acid in pickled cucumbers and caperberries during long‐term storage

SummaryThe evolution of two additives, potassium sorbate and ascorbic acid, during long‐term storage of pickled vegetables, as well as the impact of these additives on product colour, was investigated. For this investigation, cucumbers and caperberries packed in both glass bottles and plastic pouches were used. In general, the added sorbate level remained unchanged during long‐term storage irrespective of the packaging material. However, the ascorbic acid gradually disappeared at a significantly higher rate in plastic than in glass containers, and its level was higher in caperberries than in cucumbers. In the latter, the presence of sorbate caused a higher degradation rate of ascorbic acid compared to the absence of sorbate. Ascorbic acid had a protective effect against surface colour degradation in cucumbers packed in plastic pouches, whereas sorbate enhanced such degradation. However, in both pickled vegetables, ascorbic acid degradation had a significant impact on brine browning, particularly in plastic pouches.

Detection of postharvest changes of ascorbic acid in fresh-cut melon, kiwi, and pineapple, by using a low cost telemetric system

The present paper deals with a novel telemetric device combined with a carbon amperometric sensor system to determine postharvest changes of ascorbic acid (AA) in fresh-cut fruits, without displacing products out of the storage rooms. The investigation was performed on kiwi, pineapple and melon, subjected to minimal processing, packaging, cold storage, and simulated shelf life. Results demonstrated that AA content of fresh-cut fruits of all species declines differently during storage. Cold storage notably reduced the degradation rate of AA in comparison with samples stored at 20°C. The cold-chain interruption resulted in a sharp AA content reduction when the optimal storage condition was not rapidly replaced.Unpredicted results showed a high activity of oxidative enzymes, which prevented AA detection in melon samples. Our sensor system allowed us to demonstrate that both ascorbate peroxidase and ascorbate oxidase affected the oxidative stability and the nutritional quality of fresh cut melon fruits.

Effect of microwave pretreatment on the kinetics of ascorbic acid degradation and peroxidase inactivation in different parts of green asparagus (Asparagus officinalis L.) during water blanching

In this study, the effects of two blanching conditions on ascorbic acid (AA) and peroxidase (POD) in different segments of asparagus (bud, upper, middle, and butt) were investigated. The blanching treatments were: blanching in water at 70, 80 and 90°C (WB); microwave heating (900W, 30s) followed by water blanching (MW+WB). AA degradation and POD inactivation in all segments of asparagus for both treatments are well described by first-order models. The degradation rate of AA and POD is gradually increased from butt to bud segment of asparagus. In addition, MW pre-treatment could increase the Ea of AA degradation and decrease the Ea of POD inactivation during water blanching of asparagus. Therefore, it is recommended that the different segments of asparagus should be subjected to different blanching times, and MW pre-treatment could be applied for alleviating AA degradation and accelerating POD inactivation during blanching, cooking and pasteurisation in water.

Impact of edible coatings and mild heat shocks on quality of minimally processed broccoli ( Brassica oleracea L.) during refrigerated storage

The effects of edible coatings and mild heat shocks on quality aspects of refrigerated broccoli were studied. Minimally processed broccoli was coated with either chitosan or carboxymethyl-cellulose with or without a previous application of a mild heat shock of 1.5 min at 50 °C. Product was packaged in multilayered polyolefin bags and stored at 5 °C for 18 d. Quality parameters such as weight loss, texture, colour, ascorbic acid content, total chlorophyll content, oxygen concentration inside the bags, browning potential, mesophilic aerobic counts, and sensory quality, were evaluated during storage. Edible coatings exhibited a beneficial impact on broccoli quality. The weight loss in uncoated broccoli was found to be between 2 and 5 times higher compared to coated samples. During storage, coated florets from both thermally and non-thermally treated samples, presented higher retention of the (− a*/ b*) ratio indicating better green colour retention and a reduced rate of floret yellowing. Chitosan coating always presented the lower ascorbic acid degradation rates (twofold lower compared with control samples). Broccoli texture for uncoated samples increased significantly during storage. However, for carboxymethyl-cellulose coated broccoli a slight increase in texture was observed while for chitosan coated broccoli no significant changes in texture were observed throughout the storage period. After the edible coating application the microbial broccoli load dropped by around 1.5 and 0.9 logarithmic units in chitosan and carboxymethyl-cellulose films, respectively. During storage, the application of chitosan coating significantly reduced total microbial counts in the thermally and non-thermally treated uncoated samples. Among the assayed edible coatings, chitosan effectively maintained quality attributes and extended shelf life of minimally processed broccoli. The single application of a mild heat shock had a measurable influence in reducing weight loss, enzymatic browning in broccoli stems, and in delaying yellowing of broccoli florets. Moreover, chitosan coating combined with a mild heat shock showed the best performance for long-term refrigerated storage of minimally processed broccoli.

Ethylene regulates ascorbic acid content during dark-induced leaf senescence

The aim of this work was to determine if changes in antioxidant contents are directly controlled by ethylene or are indirect effects associated with modulation of leaf senescence. Detached spinach ( Spinacia oleracea L. cv Bison) leaves were treated with ethephon to induce ethylene production, placed in polyethylene bags and stored under darkness at 23 °C for 3 days. The ethephon treatment produced a rapid decrease on ascorbic acid (AA) content and an increase in its oxidised state before any leaf senescence parameters changed. Both AA synthesis and recovery from oxidised forms were affected by ethylene. In addition, leaves from Arabidopsis ( Arabidopsis thaliana (L.) Heynh) ethylene insensitive mutants ( ein2-1, ein3-1 and ein4) presented higher AA content than leaves from wt plants before dark storage. Furthermore, ein3-1 and ein4 but not ein2-1, showed slower leaf AA content declining than wt plants under dark-induced leaf senescence. The Arabidopsis mutant with constitutive triple response ( ctr1-1) showed lower leaf AA content than wt plants but similar AA degradation rate with a higher oxidised state after dark storage for 3 days. These results demonstrate that ethylene is an important factor controlling AA content in mature leaves.

Ascorbic acid in orange juice–milk beverage treated by high intensity pulsed electric fields and its stability during storage

The degradation of ascorbic acid was determined in a ready-to-drink orange juice–milk beverage treated by high intensity pulsed electric fields (PEF). The effects of PEF treatment were compared to those of heat pasteurization (90 ºC, 20 s). Four electric field strengths (15, 25, 35, 40 kV/cm) and six treatment times for each field (from 40 µs to 700 µs) were studied. Ascorbic acid degradation was adjusted to an exponential model. The obtained ascorbic acid degradation rate constants (kE) were − 0.11·10− 3 ± 0.03·10− 3 μs− 1, − 0.23·10− 3 ± 0.07·10− 3 μs− 1, − 0.42·10− 3 ± 0.09·10− 3 μs− 1 and − 0.60·10− 3 ± 0.06·10− 3 μs− 1 for field strengths of 15, 25, 35 and 40 kV/cm, respectively. For the shelf-life study a 25 kV/cm at 280 µs treatment was applied and the beverages were stored at 4 and 10 ºC. The ascorbic acid degradation rate during storage was adjusted to zero-order kinetics showing that beverages stored at 4 ºC had better ascorbic acid retention than beverages stored at 10 °C. No significant differences were found between heat pasteurization and PEF treatments during storage. Food beverages are mainly preserved and made available to the consumer by different thermal treatments which involve a destruction of desirable food constituents such as nutrients, bioactive compounds, colour, flavour and texture. The present work demonstrates that the ascorbic acid degradation in an orange juice–milk beverage treated by pulsed electric fields was adjusted to zero-order kinetics and degradation rate during storage was adjusted to first-order kinetics. The shelf life of the orange juice–milk beverages is similar so much for the pasteurized beverages as for the treated by PEF.

Determinação das constantes cinéticas de degradação do ácido ascórbico em purê de pêssego: efeito da temperatura e concentração

Ascorbic acid (vitamin C) is extensively used in the food industry, not only for its nutritional value, but also for its many functional contributions to product quality. There have been many studies on the stability of ascorbic acid in different beverages, but no study was found on the reaction rate constants for ascorbic acid degradation in peach puree. In this work, the degradation of ascorbic acid in Jade peach puree was studied in anaerobic conditions and from 70-90 °C. The peach puree concentrations tested were 12, 22 and 32 °Brix. The kinetic analysis of the data suggests that the degradation was significantly represented by zero and first-order kinetic models. The rate of ascorbic acid degradation in peach puree was temperature dependent. The average activation energy was 45 kJ.mol-1 and independent of the concentration of soluble solids.

Effect of refrigerated storage on ascorbic acid content of orange juice treated by pulsed electric fields and thermal pasteurization

Application of pulsed electric fields (PEF) can lead to longer shelf life of fruit juices with minimal product quality loss and good retention of fresh-like flavour. The aim of this study was to evaluate the effect of PEF and conventional pasteurization (90 °C, 20 s) on ascorbic acid content of orange juice, and to assess modifications in ascorbic acid concentration of orange juice stored in refrigeration at 2 and 10 °C for 7 weeks. The ascorbic acid degradation rate was −0.0003, −0.0006, −0.0009 and −0.0010 μs−1 for fields of 25, 30, 35 and 40 kV/cm, respectively. With selected PEF treatment (30 kV/cm and 100 μs) the shelf life based on 50% ascorbic acid losses was 277 days for the PEF-treated orange juice stored at 2 °C, while for the pasteurized juice was 90 days.

Study of ascorbic acid interaction with hydroxypropyl-β-cyclodextrin and triethanolamine, separately and in combination

Complexation between ascorbic acid, hydroxypropyl-β-cyclodextrin (HP-β-CD) and triethanolamine (TEA), separately and in combination, was studied in solution and solid state. The freeze-drying method was used to prepare solid complexes, while physical mixtures being obtained by simple blending. These complexes were characterized in the solid state using differential scanning calorimetry (DSC) and infrared spectroscopy (IR). Nuclear magnetic resonance spectroscopy ( 1H and 13C NMR) was used in aqueous solutions to obtain information about the mode of interaction. The degradation rate of each complex in solution was determined, and the stability constant of the complexes and the degradation rate of the ascorbic acid within the complexes were obtained. NMR studies provided clear evidence of partial inclusion into the HP-β-CD cavity, but the stability constant value was very small indicating a weak host–guest interaction. The influence of complexation on the degradation rate of ascorbic acid was evaluated, and the data obtained showed a pronounced enhancement of aqueous stability with the TEA association complex, while this effect was lower with the HP-β-CD inclusion complex. NMR experiments showed evidence of the formation of aggregates.

Thermal Degradation of Antioxidant Micronutrients in Citrus Juice: Kinetics and Newly Formed Compounds

The thermal degradation kinetics of vitamin C, two carotenoids (beta-carotene and beta-cryptoxanthin), and hesperidin, as a function of temperature, were determined for Citrus juice [Citrus sinensis (L.) Osbeck and Citrus clementina Hort. ex Tan]. The influence of dissolved oxygen on the rate of ascorbic acid degradation was also assessed. Analysis of kinetic data suggested a first-order reaction for the degradation of vitamin C and carotenoids. The kinetics parameters Dtheta, z, and Ea have been calculated. Following the Arrhenius relationship, the activation energy of ascorbic acid was 35.9 kJ mol-1 and agreed with the range of literature reported value. The results on vitamin C and carotenoids from citrus juice made it possible to validate the predicting model. Thermal degradation of carotenoids revealed differences in stability among the main provitamin A carotenoids and between these and other carotenoids belonging to the xanthophyll family. The activation energies for the two provitamin A carotenoids were 110 and 156 kJ mol-1 for beta-carotene and beta-cryptoxanthin, respectively. On the other hand, no degradation of hesperidin was observed during thermal treatment. Finally, the vitamin C in citrus juice was not as heat sensitive as expected and the main provitamin A carotenoids present in citrus juice displayed a relative heat stability. The high-performance liquid chromatography-diode array detection-mass spectrometry analysis of degradation products showed that the isomerization of the epoxide function in position 5,6 into a furanoxide function in position 5,8 was a common reaction for several xanthophylls. These findings will help determine optimal processing conditions for minimizing the degradation of important quality factors such as vitamin C and carotenoid in citrus juice.

Kinetic and prediction studies of ascorbic acid degradation in normal and concentrate local lemon juice during storage

Kinetics of the loss of ascorbic acid (AA) in local lemon juice of 9° and 50° Brix stored at 25, 35, and 45 °C for 4 months have been investigated. The results indicate that increases of concentrations and temperatures increase the rate of AA degradation. The calculated values of activation energies ( E ≠) and frequency factors ( A) at different Brix imply that the concentration of juice does not change the mechanism of degradation. Thermodynamic functions of activation (Δ G ≠, Δ H ≠, Δ S ≠ and K ≠) have been determined and considered briefly. A direct equation for estimation of the shelf life of stored juice with respect to first-order losses of AA, at any specific temperature and degradation ratio, has been derived and programmed successfully.