Effect of ozone processing on anthocyanins and ascorbic acid degradation of strawberry juice

Strawberry juice samples were ozonated with processing variables of ozone concentration (1.6–7.8% w/w) and treatment time (0–10 min). Effects of processing variables on anthocyanins (P3G), ascorbic acid (AA) and colour values (L^∗, a^∗, and b^∗) were determined. Significant reductions in anthocyanin content (98.2%) and ascorbic acid (85.8%) were observed at an ozone concentration of 7.8% w/w and a treatment time of 10 min. The changes in lightness (L^∗) values and total colour difference (TCD) values were fitted well to zero-order kinetics, whereas, a^∗, b^∗ followed first-order kinetics. P3G and AA were fitted to first order and fraction conversion models. The rate constants for L^∗, a^∗, b^∗ and TCD were linearly correlated with ozone concentration, whereas, P3G and AA were exponentially related.     

Stability of anthocyanins and ascorbic acid in sonicated strawberry juice during storage

The stability of anthocyanins and ascorbic acid in sonicated strawberry juice during storage was investigated. Strawberry juice was sonicated at varying acoustic energy densities (AEDs) ranging from 0.33 to 0.81 W/mL and treatment times of 0–10 min. The degradation kinetics of sonicated samples followed first-order kinetics. Degradation rate constants were linearly correlated with AED (R ² > 0.91). Selected samples were stored for 10 days at 4 and 20 °C. A second-order polynomial model was employed to investigate the effects of storage time and processing variables. During storage higher loses were observed at a storage temperature of 20 °C compared to 4 °C. Predictive models developed for anthocyanins and ascorbic acid content were highly significant (P < 0.0001) and closely correlated to the experimental data (R ² > 0.91). Degradation mechanisms for anthocyanins and ascorbic acid due to sonication and storage are proposed.     

Kinetics of ascorbic acid degradation in fruit-based infant foods during storage

The kinetics of ascorbic acid (AA) degradation in a fruit-based beikost product added with AA were determined after storage at 4, 25, 37 and 50 °C during 4, 8, 12, 16 and 32 weeks in plastic polypropylene/ethylene–vinyl alcohol vacuum packaging. It was confirmed that AA degradation followed an Arrhenius first-order kinetics, with an activation energy of 20.11 ± 0.33 kcal mol⁻¹. No AA losses at 4 °C were recorded during the entire storage period. In contrast, a time- and temperature-dependent decrease (p < 0.05) in AA was observed at the other tested temperatures – the degradation rate decreasing from 50 °C to 25 °C, as expected. AA percentage retention at the end of storage ranged between 6.4% (50 °C/16 weeks) and 100.9% (4 °C/32 weeks).     

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 (ΔG^≠, ΔH^≠, ΔS^≠ 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.     

Effect of high pressure processing on yield,quality and storage stability of peanut paneer

Paneer was prepared from peanuts by soaking the nuts for 8 h followed by removal of skin, grinding, extraction of milk and coagulation using calcium sulphate (1% solution). In another method the peanut milk was high pressure processed at 600 MPa for 5 min before coagulation. The obtained paneer samples were vacuum packed and kept at refrigerated temperature (6 ± 1 °C) for storage and evaluated for physico‐chemical, sensory and microbial attributes. High pressure processing of milk before coagulation resulted in increase in paneer yield significantly (P < 0.05) as well as maintained the quality of the paneer to a better extent as compared to control during refrigerated storage for a period of 45 days.     

Ascorbic acid degradation kinetics of sonicated orange juice during storage and comparison with thermally pasteurised juice

Ascorbic acid degradation kinetics of sonicated orange juice during storage were determined and compared to thermally pasteurised samples. Acoustic energy densities (AED) ranging from 0.30 to 0.81 W/mL and treatment times of 2-10 min were investigated. The degradation kinetics of sonicated samples followed first-order kinetics (R² ≥ 0.91) during processing. During storage ascorbic acid degradation of sonicated samples followed the Weibull model (R² ≥ 0.97) with β values ranging from 0.662 to 0.697. Comparatively, first-order degradation kinetics were observed during storage for thermally pasteurised (R² = 0.98) and control samples (R² = 0.96). Increased shelf life based on ascorbic acid retention was found for sonicated samples compared to thermally pasteurised samples. Predicted shelf life for sonicated orange juice ranged from 27 to 33 days compared to 19 days for thermally pasteurised juice during storage at 10 °C. These results indicate that sonication results in enhanced retention of ascorbic acid in orange juice during storage compared to thermal processing.     

抗氧化剂对大枣汁加工中VC的影响

大枣汁加工过程中VC的保存是影响大枣产品质量的关键技术。通过不同抗氧化剂处理试验,表明植酸处理对还原型VC的保存效果最好,其次是0.04%的六偏磷酸钠和0.06%的Na2EDTA;茶多酚和Na2EDTA对氧化型VC的降解起抑制作用,六偏磷酸钠可使氧化型VC的含量增高。     

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.     

Effect of ascorbic acid and citric acid on the quality of salted Chinese cabbage during storage

Changes in color, browning indices, enzyme activity, and physical and chemical quality during the storage period were investigated to assess the effectiveness of storage period extension along with the addition of ascorbic acid (AA) and citric acid (CA) to salted Chinese cabbage. After 16 days of storage, the change in chromaticity value showed treatment with 0.5% CA showed the lowest change in the brown index during the storage period. The control showed the highest residual activity of polyphenol oxidase among control, AA, and CA-treated salted cabbage. AA and CA treatment effectively inhibited the initial populations of microorganisms including total aerobic bacteria, lactic acid bacteria, and yeast and molds in salted Chinese cabbage during storage. Further, the texture, i.e., hardness, chewability, and elasticity, tended to decrease with increasing storage. These results suggest that treatment with AA could help maintain the quality of salted Chinese cabbage during the storage period.     

The effects of six phenolic acids and tannic acid on colour stability and the anthocyanin content of mulberry juice during refrigerated storage

Six phenolic acids and tannic acid are added to fresh mulberry juice to enhance the colour. Effects of these copigments on colour stability and the anthocyanin content of mulberry juice are investigated while being stored at 4 °C for 30 days. Results suggest that the addition of the copigments markedly increases the maximum absorbance of mulberry juice. Cyanidin-3-glucoside is the major anthocyanin, followed by cyanidin-3-rutinoside. Furthermore, the retention rate of the total anthocyanin, cyanidin-3-rutinoside and cyanidin-3-rutinoside increases after the addition of all copigments. The effect of ferulic acid on the stability of total anthocyanin, cyanidin-3-glucoside and cyanidin-3-rutinoside in mulberry juice is the best, 89.52%, 86.90% and 94.46% respectively (66.56%, 62.58% and 73.60% in the control group). Researchers recommend the addition of ferulic acid, p-coumaric acid and caffeic acid – all of which belong to the hydroxycinnamic acid group, to the mulberry juice to enhance the colour stability and anthocyanin content.     

Effect of high pressure, temperature, and storage on the color of porcine longissimus dorsi

The color of pork longissimus dorsi high pressure (HP) treated at 200 to 800MPa at 5 and 20°C for 10min was determined to a high degree by pressure level and to a lesser degree by temperature. Severe color changes appeared up to a threshold pressure at 400MPa. HP treatment at 20°C compared to 5°C resulted in meat, which was less red and slightly lighter. Storage at 2°C for 6days had no effect on lightness due to no further protein denaturation, but meat HP treated above 300MPa became significantly less red and more yellow within the first day of storage. Reflectance spectra showed that a short-lived ferrohemochrome myoglobin species was formed during HP treatment at 300 to 800, but transformed into a brown, ferric form of the pigment within the first day of storage. This explains the observed changes in the redness and yellowness after one day of storage.     

超高压处理对蓝莓汁品质的影响

以蓝莓汁为原料,采用200～500MPa高压分别对蓝莓汁处理5～15min,对处理后的蓝莓汁进行微生物和理化指标检测。研究结果表明:超高压处理杀菌效果显著,400MPa处理10min已无菌落检出;高压处理对蓝莓汁色泽、还原糖、可溶性固形物的影响较小,蓝莓汁中的花青素和VC含量在高压处理后保留率达90%以上,而总酸和总酚含量略有下降。      

Preservation effect of high pressure processing on ascorbic acid of fruits and vegetables: A review

High Pressure Processing (HPP) is a well‐established nonthermal technology for ensuring microbial safety and nutritional quality of foods. Ascorbic acid (AA) is highly labile antioxidant, susceptible to degradation when exposed to oxygen, change in pH, temperature, or pressure. Preservation of AA in fruit and vegetable products is a prime concern for food processors. This review summarizes recent data on the effect of HPP on AA content of different fruits and vegetables, and their products. In most of the food products, HPP has supported either preservation or better retention of AA after pressurization (400–600 MPa/5–10 min) at lower or room temperature. High pressure processed foods have demonstrated better stability of AA during refrigeration storage as compared to thermally processed ones. These studies establish the positive implications of HPP and justify its potential use as a promising preservation technique to safeguard AA in food products.     

Quantitative modelling approaches for ascorbic acid degradation and non-enzymatic browning of orange juice during ultrasound processing

The objective of this study was to develop a deterministic modelling approach for non-enzymatic browning (NEB) and ascorbic acid (AA) degradation in orange juice during ultrasound processing. Freshly squeezed orange juice was sonicated using a 1500 W ultrasonic processor at a constant frequency of 20 kHz and processing variables of amplitude level (24.4–61.0 μm), temperature (5–30 °C) and time (0–10 min). The rate constants of the NEB and AA were estimated by a primary model (zero and first order) while their relationship with respect to the processing factors was tested for a number of models, i.e., second order polynomial, different types of Ratkowsky-type model, and an Arrhenius-type model. The non-monotonic behaviour of NEB has been described more accurately by the use of a polynomial model. The rate constants of AA were described by a similar type of model having a monotonic behaviour. A synergistic effect of temperature for different amplitudes on the rate constant of both NEB and AA was observed, while an antagonistic effect of amplitude on the rate of NEB was evident. The models with the best fit were integrated to produce contour plots for the combined amplitude and temperature. The constructed contour plots illustrate that low temperatures and intermediate amplitudes, i.e., 42.7 μm, result in lower NEB and AA deterioration and consequently better quality orange juice. The overall developed modelling approaches exploit quality data in order to identify the optimal processing regions for eliminating quality deterioration of orange juice during ultrasound processing which is of high importance to the food industry.     

Antioxidant capacity,ascorbic acid,total phenols and carotenoids changes during harvest and after storage of Hayward kiwifruit

The influences of harvest time and storage on the quality indices and nutritional content of kiwifruit were evaluated. Antioxidant capacity, ascorbic acid, total phenol content, carotenoids, soluble solids content and flesh firmness were determined in kiwifruit gathered at two different time (T1: 17-11-2005 and T2: 24-11-2005) and stored at 0 °C, for 2 or 6 months (S1 and S2, respectively). At the end of the cool storage, fruits were maintained for a week at 25 °C (S1 + 7d and S2 + 7d).     

Kinetics of the formation of radicals in meat during high pressure processing

The kinetics of the formation of radicals in meat by high pressure processing (HPP) has been described for the first time. A threshold for the radicals to form at 400 MPa at 25 °C and at 500 MPa at 5 °C has been found. Above this threshold, an increased formation of radicals was observed with increasing pressure (400–800 MPa), temperature (5–40 °C) and time (0–60 min). The volume of activation (ΔV^#) was found to have the value −17 ml mol⁻¹. The energy of activation (E_a) was calculated to be 25–29 kJ mol⁻¹ within the pressure range (500–800 MPa) indicating high independence on the temperature at high pressures whereas the reaction was strongly dependent at atmospheric pressure (E_a = 181 kJ mol⁻¹). According to the effect of the processing conditions on the reaction rate, three groups of increasing order of radical formation were established: (1) 55 °C at 0.1 MPa, (2) 500 and 600 MPa at 25 °C and 65 °C at 0.1 MPa, and (3) 700 MPa at 25 °C and 75 °C at 0.1 MPa. The implication of the formation of radicals as initiators of lipid oxidation under HPP is discussed.     

Effect of ascorbic acid on the odours of cloudy apple juice

Ascorbic acid is used in apple juice as an antibrowning agent. This study investigated the effect of ascorbic acid (0.0–0.2% w/v) on the odours of cloudy apple juice using sensory evaluation and gas chromatography (GC). The increase in ascorbic acid concentration in the apple juice resulted in increases in green and unnatural odours and decreases in fresh, fruity and apple-like odours. In the GC determination, 23 volatile compounds were detected in apple juice. Aroma value, which showed the relative importance of volatile compounds, was used to elucidate the changes in odours of apple juice due to the addition of ascorbic acid. The aroma values of hexanal and trans-2-hexenal in the apple juice with 0.2% w/v ascorbic acid increased about 4 and 5-fold from those in the ascorbic acid-free apple juice, respectively. On the other hand, the aroma values of esters insignificantly changed in the apple juice with ascorbic acid. The increases in aroma values of aldehydes corresponded well with the increase in green odour in the apple juice with ascorbic acid.     

Effect of high pressure on the microbiological quality of cooked chicken during storage at normal and abuse refrigeration temperatures

Vacuum-packaged cooked poultry meat was treated at a range of pressures (400–600 MPa) and hold times (1, 2 and 10 min), followed by storage at 4°, 8° or 12 °C for up to 35 days. Weissella viridescens was found to be the dominant microorganism in the pressure-treated meat, constituting 100% of the microflora identified at 500 and 600 MPa. None of the pressure-treated samples had obvious signs of spoilage during the 35 day storage period, even when the Weissella count was >7 log₁₀ cfu/g. Studies on a typical W. viridescens isolate showed it to be relatively pressure-resistant in poultry meat, with <1 log reduction in numbers after a treatment of 2 min at 600 MPa. Agar diffusion assays showed that the isolate also caused the inhibition of a number of Gram-positive and Gram-negative pathogens, including strains of Clostridium botulinum, Listeria monocytogenes, Bacillus cereus and Escherichia coli. The selection of a pressure-resistant organism, such as this Weissella sp. could be advantageous in extending the shelf-life, and also microbiological safety, of the cooked meat, as it could give protection in addition to the pressure treatment itself.