Residual Polyphenol Oxidase Activity Research Articles

Unleashing the potential of flash vacuum expansion: an innovative approach for Andean Blackberry (Rubus glaucus Benth) Processing

Andean Blackberry fruits (Rubus glaucus Benth) have promising market potential with notable nutritional and antioxidant properties; however, their limited 3-6day shelf-life presents considerable challenges. A flash vacuum expansion (FVE) process coupled with vacuum de-pulping was used to obtain puree from blackberry fruits. Different steam heating holding times (53, 75, 85, and 95 s) were tested at a pressure of 130 kPa. After FVE and vacuum de-pulping (5kPa), various parameters, including alcohol insoluble residues (AIR), residual activity of polyphenol oxidase (RAPPO), anthocyanins, ascorbic acid and ellagitannin retention, rheological properties, and microbial reduction, were evaluated in the purees. Optimal steam heating time of 85 seconds was selected for the FVE process, showing outstanding retention rates of 98% for cyanidin-3-O-glucoside and 88% for ascorbic acid, along with enhanced ellagitannins extraction from torus and seed blackberries into the puree. The purees displayed a gradual shear-thinning flow behavior, positively correlated with the increase in %AIR. A reduction greater than 5 Log10 CFU / mL was achieved for molds, yeasts, aerobic mesophilic, and coliforms counts for all the treatments. Nectar and sweetened puree products developed from the optimal FVE processed puree, received favorable acceptance from consumers, with a high intention to purchase. The findings demonstrated that this innovative process has great potential for developing of high-quality products.

Nth order kinetic modelling of peroxidase and polyphenol oxidase inactivation in kiwifruit juice during cold plasma and thermal treatment

The current study examines the effect of thermal and cold plasma (CP) treatment on the inactivation of polyphenol oxidase (PPO) and peroxidase (POD) in kiwifruit juice. The residual activity of POD and PPO were fit to nth-order kinetics at a voltage, juice depth, and treatment time range of 18–30 kV, 2–10 mm, and 2–10 min, respectively. During thermal treatment, the inactivation order (n) value for POD and PPO were 1.07 and 1.06, whereas, for the cold plasma treatment, it was 2.07 and 2, respectively. The higher D-value of POD than PPO makes the former enzyme more resistant to plasma treatment. The Fourier-transform infrared spectroscopy (FTIR) revealed an increase in the proportion of β-sheet structure from 23 to 28% and a decrease in α-helix from 28 to 20% compared to the control sample. In comparison to thermal treatment, CP treatment effectively retained the biochemical attributes of juice. Industrial relevanceThe PPO and POD inactivation is necessary for preparing stable kiwifruit juice. A detailed kinetic study is mandatory for designing and optimizing the process, as both enzymes react in their way depending on the origin and experimental range. The generated kinetic model can be used to establish the optimum conditions for inactivating enzymes during CP treatment.

Processing of encapsulated flaxseed oil‐rich banana‐based (Dwarf cavendish) functional fruit leather

AbstractBanana fruit leather enriched with flaxseed oil in the form of encapsulates was prepared. Initially, the optimized conditions of 836 W power for 4 min for blanching of banana using microwave were obtained by Response Surface Methodology with residual polyphenol oxidase activity and vitamin C retention taken as responses. The addition of maltodextrin, citric acid, and pectin for blending with banana puree to obtain a non sticky puree having low pH was also optimized, while keeping the quantity of sugar constant. The blend was added with 5% encapsulates of flaxseed oil (FSO) in alginate used as wall material. The blend was dried in a tray drier at 40, 50, and 60°C and the drying behavior of the leather was studied. Henderson and Pabis model satisfactorily described the drying kinetics of banana leather. GAB model described well the sorption behavior of the leather. Fat content in the optimized leather increased to 3.27% due to addition of FSO. The ash content in the enriched leather was 5.56 ± 0.03%. Phenolic content increased from 91.84 ± 0.06 mg GAE/100 g to 100.90 ± 0.05 mg GAE/100 g for the enriched leather as compared to the control. The study revealed that the banana leather can be considered as a functional snack food due to the availability of flaxseed oil (rich in ω‐3 fatty) and high phenolic acid content.Practical ApplicationsBanana can be processed into functional fruit leather with the addition of flaxseed oil encapsulated beads to complement the fast moving consumer goods market. Developing the banana leather by drying enhances its shelf life while encapsulation increases the stability of flaxseed oil for a prolonged storage of the product. Flaxseed oil is rich in ω‐3 fatty acid, an important bioactive compound required for good human health. Moreover, modeling of the drying behavior allows optimization of the process, which is necessary for designing of energy efficient industrial flow dryers. Therefore, this study on development of a novel functional product and drying kinetics will give a new edge to the industrial processing of similar snack products with a potential alternative to reduce the waste of banana as a raw material.

Residual polyphenol oxidase and peroxidase activities in high pressure processed bok choy (Brassica rapa subsp. chinensis) juice did not accelerate nutrient degradation during storage

Polyphenol oxidase (PPO) and peroxidase (POD) cannot be fully inactivated by commercial high pressure processing (HPP) operations, and their residual activities may accelerate nutrient degradation during storage. This study hence aimed to establish the effect of residual enzyme activity on nutrient preservation in bok choy (Brassica rapa subsp. chinensis) juice. Bok choy juice was treated at 600 MPa for up to 20 min and enzyme inactivation, nutrient retention immediately after treatment and nutrient preservation during storage were determined. High residual PPO (85.1 ± 2.6%) and POD (68.5 ± 1.0%) activities remained after 20 min of treatment. Increasing the pressure holding time to enhance enzyme inactivation did not compromise total antioxidant capacity, vitamin C, carotenoids, isothiocyanates and vitamin K levels. Neither did it significantly reduce the vitamin C degradation rate during refrigerated storage. Maximising enzyme inactivation may thus not be necessary for nutrient preservation during the storage of HPP-treated bok choy juice. Industrial relevance textWith HPP, an increase in pressure or holding time is required to achieve higher levels of enzyme inactivation. Without the need to maximize PPO and POD inactivation, juice processors may employ the minimum pressure and holding time required for microbial inactivation. As vegetative bacteria are typically less resistant to HPP inactivation than these enzymes, this could translate to reduced energy costs and increased throughput.

Effect of microfluidization on quality characteristics of sapodilla (Manilkara achras L.) juice

Various oxidative enzymes account for the quality degradation of sapodilla (Manilkara achras L.) juice and need to be inactivated through emerging and continuous green pressure processing technology. In this study, pressurization of sapodilla juice was attempted via microfluidization (MF) at pressure range of 10,000–30,000 pound per square inch (psi) with 1–3 passes or cycles. The impact of microfluidization on the activity of polyphenol oxidase (PPO), peroxidase (POD), color, total soluble solid (TSS), viscosity, serum cloudiness along with particle size, and microbial load of sapodilla juice was assessed. Results showed that microfluidization (MF) decreased the residual PPO activity from 100 to 80.78 % and POD activity from 100 to 40.57%. However, TSS (18.81–19.01 %), viscosity (2.64–2.06 cP), serum cloudiness (2.19–1.22 %) and total color change (3.19–18.54) was also significantly affected. Most of these changes were observed due to particle size (PS) reduction that varied from 65.19 to 8.13 μm. Microfluidized juice revealed color improvement at particular MF pressure and pass due to enzyme inactivation. Moreover, lowest microbial load (2.89 Log CFU/ mL) was found at 30,000 psi/3 pass of MF as compared to control sample (unprocessed juice) (7.57 Log CFU/ mL). Consequently, MF can be potential candidate in processing of juices against spoilage.

Retention of polyphenols and vitamin C in cranberrybush purée (Viburnum opulus) by means of non-thermal treatments

The effects of high pressure processing (HPP; 200–600 MPa for 5 or 15 min) and pulsed electric field (PEF; 3 kV/cm, 5–15 kJ/kg) treatment on physicochemical properties (conductivity, pH and total soluble solids content), bioactive compounds (vitamin C, total phenolic (TPC), total flavonoid (TFC), total anthocyanin (TAC) and chlorogenic acid contents), antioxidant capacities (DPPH and CUPRAC assays) and polyphenol oxidase (PPO) activity of cranberrybush purée were evaluated immediately after processing. The results were compared to an untreated purée. According to the results, conductivity increased significantly after PEF (15 kJ/kg) treatment. PEF and HPP treatments resulted in a better retention of bioactive compounds (increase in TPC in the range of ~4–11% and ~10–14% and TFC in the range of ~1–5% and ~6–8% after HPP and PEF, respectively) and antioxidant activity (as measured with CUPRAC method) compared to untreated sample. HPP reduced residual enzyme activity of PPO comparatively better than PEF.

Enzyme inactivation and its kinetics in a reduced-calorie sapodilla (Manilkara zapota L.) jam processed by thermal-assisted high hydrostatic pressure

The effect of high-pressure processing parameters within the domain of 300−600 MPa/25−65 °C/0−30 min was evaluated on polyphenol oxidase (PPO) and peroxidase (POD) inactivation in a reduced-calorie sapodilla jam. The residual activity of PPO and POD enzymes was significantly reduced (up to 57% for PPO and 43% for POD) by temperature followed by pressure and time, and all the process parameters showed a synergistic effect represented by contour plots. However, POD was more baroresistant than PPO. The rate constants obtained from the first-order kinetics applied to enzyme inactivation during isobaric-isothermal phase varied from 2.1 × 10−3 min−1 to 1.36 × 10−2 min−1 for PPO, and 2.0 × 10−3 min−1 to 7.8 × 10−3 min−1 for POD. Various other kinetic parameters viz. D value, DP, ND, zT, zP, activation energy, and activation volume were also obtained to compare the results. Also, the HPP jam samples were microbiologically safe.

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 16days 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.

Impact of processing and storage conditions on color stability of strawberry puree: The role of PPO reactions revisited

The effect of pre-heating fresh strawberries (hot break) and the use of refrigerated temperatures prior to pasteurization on the stability of anthocyanins, vitamin C, color and polyphenol oxidase (PPO) activity during storage (42 days at 35 °C) of strawberry puree was studied. Hot break resulted in 20% residual PPO activity and caused 10% anthocyanin degradation, whereas vitamin C was unaffected. After mashing, purees were stored at 4 °C and 25 °C for 3 h. During this period, anthocyanins and PPO activity remained constant independently of the processing history but ascorbic acid was oxidized faster at 25 °C. Pasteurization caused complete inactivation of PPO, reduction of anthocyanins (25%), of a* value (6%) and of vitamin C (50%). Neither partial inactivation of PPO early in the processing (hot break) nor the use of refrigeration prior to pasteurization had a positive effect on color and anthocyanin stability of strawberry puree during subsequent storage, suggesting that PPO-derived reaction products formed during processing have a very limited impact on color degradation during shelf-life. • Different strawberry puree manufacturing processing conditions were evaluated. • Hot break did not improve color stability during further processing and storage. • Refrigeration prior to pasteurization prevented ascorbic acid oxidation. • PPO reactions before pasteurization do not affect color degradation during storage. • “Impact of processing and storage conditions on color stability of strawberry puree: the role of PPO reactions revisited”.

Effects of radio-frequency-assisted blanching on the polyphenol oxidase, microstructure, physical characteristics, and starch content of potato

The effects of radio-frequency (RF)-assisted blanching and conventional hot water blanching (HWB) on the polyphenol oxidase (PPO), microstructure, physical characteristics, and starch granules in potato were investigated. The residual activity of PPO decreased from 60.47% to 1.35% with increased RF heating temperature (50–90 °C). Moreover, RF achieved a similar level of enzyme inactivation as HWB at lower temperature (70 °C), thereby maintaining the good physical characteristics. With increased temperature from 50 °C to 90 °C, weight loss (1.15%–6.23%) and relative electrolyte leakage (REL) (6.57%–96.96%) increased. Transmission electron micrographs revealed that the increase in REL was due to the gradual degradation of cell membranes and walls. Confocal laser scanning micrographs suggested that RF and HWB treatments changed the cell morphology and gelatinized the starch granules, leading to texture softening. Furthermore, differential scanning calorimetry thermograms showed that ΔH decreased from 2.80 J/g to 0 J/g with increased temperature. All these findings indicated that the change in physical characteristics of potato depended on its microstructure during RF blanching.

Effect of cold plasma on polyphenol oxidase inactivation in cloudy apple juice and on the quality parameters of the juice during storage

Direct cold plasma treatment has been investigated as an alternative non-thermal technology as a means of maintaining and improving quality of fresh cloudy apple juice. Process variables studied included type of plasma discharge, input voltage and treatment time on polyphenol oxidase (PPO) inactivation. Spark discharge plasma at 10.5 kV for 5 min was the best treatment, with near total inactivation of PPO achieved, although good PPO inactivation was also recorded using shorter treatment times. Residual activity (RA) of PPO was 16 and 27.6% after 5 and 4 min of treatment respectively. This PPO inactivation was maintained throughout the storage trials, but decreased with samples treated for a shorter time. Plasma treatment improved key quality parameters of Golden delicious cloudy apple juice, with retention of critical quality parameters during extended storage trials. Color was the most noticeable change, which was enhanced with retention of a greener color. An increase of 69 and 64% was obtained in the total phenolic content after 4 and 5 min of treatment, respectively. Therefore, cold plasma was demonstrated to be a good alternative to traditional heat treatments for enhanced quality retention of fresh cloudy apple juice and over its storage.

Optimisation of steam blanching on enzymatic activity, color and protein degradation of alfalfa (Medicago sativa) to improve some quality characteristics of its edible protein.

The use of alfalfa protein in human food is limited by its low quality. Response Surface Methodology was employed to optimise the combined effects of different steam blanching conditions on the enzymatic activity, browning and protein degrading which cause undesirable characteristics. The optimum conditions were: steaming time 4.36 min, particle size 23 mm, time from harvesting to steaming 2 h leading to a residual activity of polyphenol oxidase of 1.31% and a completely inactivation of peroxidase. The Browning Index value was 108.3 and the non-protein nitrogen 170.2 (g kg-1 TN). The browning and protein degradation rates of alfalfa treated under the optimum conditions were much lower than the control alfalfa after 60 days ensiling. This suggests that blanching of fresh whole alfalfa leaves under the optimum conditions was helpful for avoiding the appearance of the dark color and degradation of the extracted protein, improving its quality for human consumption.

Effect of thickness on non-fried potato chips subjected to infrared radiation blanching and drying

This study investigated the effect of thickness (0.6, 0.8, 1.0 and 1.3 mm) on non-fried potato chips that were treated with a sequential infrared (IR) radiation blanching and drying method. The process characteristics such as the residual polyphenol oxidase (PPO) activity, moisture content reduction and drying rate of IR-treated potato slices were studied. The quality characteristics, including color and texture, were also determined. The residual PPO activity decreased with the increase in sample thickness, in a range of 2.13–8.81% after IR-blanching. The first-order kinetics fitted well for the PPO inactivation curve. The final moisture content (MC) of samples with various thicknesses reached a range of 3.85–4.51% (w.b.) after IR-treatment. The thinner sample had a faster drying rate than the thicker slices. The drying behavior can be described well using the Midilli model. Surface color changes of potato chips with different thickness were expressed by a 0.12-fold decrease in the L* value, and a 4.72-fold and 0.57-fold increase in the a* and b* values, respectively, after IR-treatment. The values of hardness increased by 0.96-fold with the increase in sample thickness from 0.6 to 1.3 mm. In addition, the sensory evaluation revealed that consumers preferred the sample with a thickness of 0.8 mm based on the overall degree of liking.

Inactivation of apple (Malus domestica Borkh) polyphenol oxidases by radio frequency combined with pulsed electric field treatment

SummaryRadio frequency (RF) preprocessing combined with pulsed electric field (PEF) processing was employed to inactivate polyphenol oxidase (PPO) in apple juice. PPO enzyme levels, loss of total phenolic content (TPC), colours and volatile components in the apple juice were subsequently determined and compared with conventional processing methods (60 °C for 10 min and 70 °C for 10 min). Results indicated that, when the apple tissue was preprocessed using RF for 10 min, the residual activity of PPO decreased to 13.57%; when the squeezed juice was processed by PEF, the residual activity decreased to about 5% at 15–35 kV cm−1 for 400 μs. RF treatment caused no significant loss in TPC. Compared with the conventionally processed samples, the apple juice that was RF‐treated for 10 min and PEF‐treated at 15 kV cm−1 for 400 μs increased its lightness and maintained its fresh‐like flavour.

Combined effect of ultrasound, heat, and pressure on Escherichia coli O157:H7, polyphenol oxidase activity, and anthocyanins in blueberry (Vaccinium corymbosum) juice

The objective of this study was to evaluate the effect of different treatments—heat treatment (HT), sonication (SC), thermosonication (TS), manosonication (MS), manothermal (MT), and manothermosonication (MTS) on Escherichia coli O157:H7, polyphenol oxidase (PPO), and anthocyanin content in blueberry juice. First, samples were treated at different temperatures (30, 40, 50, 60, 70, and 80°C) and power intensities (280, 420, 560, and 700W) for 10min. Subsequently, samples were treated using combinations of power intensity and mild temperature for 10min. For further study, samples were treated using HT (80°C), TS (40°C, 560W), MT (350MPa, 40°C), MS (560W, 5min/350MPa), or MTS (560W, 5min, 40°C/350MPa, 40°C) for 5, 10, 15, 20min for each treatment, and the results compared between treatments. HT significantly reduced PPO activation (2.05% residual activity after only 5min), and resulted in a 2.00-log reduction in E. coli O157:H7 and an 85.25% retention of anthocyanin. Escherichia coli O157:H7 was slightly inactivated by TS after 5min (0.17-log reduction), while residual PPO activity was 23.36% and anthocyanin retention was 98.48%. However, Escherichia coli O157:H7 was rapidly inactivated by MTS (5.85-log reduction) after 5min, while anthocyanin retention was 97.49% and residual PPO activity dropped to 10.91%. The destruction of E. coli cells as a result of these treatments were confirmed using SEM and TEM. Therefore, a combination of sonication, high pressure, and mild heat allows the safety of blueberry juice to be maintained without compromising the retention of desirable antioxidant compounds.

Effect of microwave treatment on enzyme inactivation and quality change of defatted avocado puree during storage

Abstract We evaluated the effect of different power densities, 11.0, 7.7 and 4.4 W/g, of microwave (MW) treatment on inactivation of polyphenol oxidase (PPO) and pectin methylesterase (PME), and on changes in chlorophyll and total phenolic content of defatted avocado puree (DAP). Changes in sensory quality, such as color and rheology, during 4 weeks storage at 4 °C were also investigated. The temperature of DAP rose to 70 °C in 37 and 122 s at 11 and 4.4 W/g MW, respectively. It was observed that over 80% PPO could be inactivated in 80 s at 11.0 W/g. During storage, the residual PPO activity of untreated samples continuously increased to 250% whereas for MW treated samples the residual PPO activity remained constant at around 20%; however, no PME activity was detected. At the end of storage, for samples treated at 11 W/g for 80 s total phenolic content increased by 29.41% and negligible losses in chlorophyll a and b content occurred whereas for control samples the decrease in chlorophyll a and b was 38.2% and 37.1%, respectively. Although not significant (p > 0.05), the a* value of MW treated samples increased whereas the L* value decreased. MW treatment did not alter the pseudoplastic flow behavior and particle size distribution of DAP, while the apparent viscosity was slightly higher than that of untreated DAP at lower shear rates (1–10 s− 1). Industrial relevance The defatted avocado puree (DAP) can be used in cosmetics industry as an ingredient and can also be used in human consumption as it helps to reduce body weight and total hepatic fat. However, due to polyphenol oxidase (PPO) present in DAP, browning can take place and therefore PPO must be inactivated. We have found that microwave treatment could considerably lower the activity of PPO and aids in preserving the sensory and nutritional quality during storage at 4 °C.

High pressure thermal processing of pears: Effect on endogenous enzyme activity and related quality attributes

Abstract The effect of high pressure-thermal (HPT) processing (600 MPa, 20–100 °C) on the activity of pear enzymes and related quality attributes was investigated. HPT processing at 20 °C for 5 min resulted in 32%, 74% and 51% residual activities of polyphenol oxidase (PPO), peroxidase (POD) and pectin methylesterase (PME), respectively. Increasing processing temperature to 40 and 60 °C reduced the level of PPO and POD inactivation, with the maximum residual activities of 64% and 123%, respectively observed after 3-min treatments at 40 and 60 °C. Overall, HPT at 20 to 60 °C had minimal effect on quality, although enzymatic browning was observed upon air exposure. HPT at 80 to 100 °C caused almost complete inactivation of PPO and POD with 90% and 92% inactivation respectively after 3-min processing at 100 °C, which reduced browning upon air exposure. Nevertheless, the lowest texture retention of 22% was observed under this condition. Industrial relevance The study examined the effects of combined high pressure thermal processing on quality related pear enzymes and related instrumental quality attributes such as colour and texture. The study enabled identification of processing regimes for enzyme inactivation and quality retention. The excellent quality retention following HPP at 20 to 40 °C makes this condition suitable for ‘fresh-like’ small portion products for immediate consumption after unpacking that do not require complete PPO and POD inactivation. On the other hand, the almost complete inactivation of oxidative enzymes PPO and POD at 100 °C makes this condition more appropriate for the production of bulk products for food service applications or pureed ingredients for baby food, or pear pieces for yoghurt, that require PPO inhibition but not necessarily high firmness retention.

Effects of Heat Treatment on Polyphenol Oxidase Activity and Textural Properties of Jackfruit Bulb

The jackfruit bulbs were subjected to different heat treatments and the residual polyphenol oxidase (PPO) activity, browning index (BI), the concentration of vitamin C (Vc) and textural properties (TP) after freeze drying (FD) were determined. The results showed that PPO, BI and Vc were 5.83%, 107.69, 4.11 mg/100 g and 10.66%, 84.09 and 4.30 mg/100 g at the optimal time or temperature, respectively. The time was significantly negatively correlated to hardness, fracturability, chewiness, resilience and Vc concentration. The temperature was significantly positively correlated to adhesiveness, whereas it was significantly negatively correlated to hardness, gumminess, chewiness, resilience, BI and Vc concentration (P < 0.05). Based on PPO activity, BI, the concentration of Vc and TP, the optimal pre-drying conditions were temperature of 80C and time of 4 min. This paper could provide good guidance for other fruit processing based on the pretreatments of FD jackfruit. Practical Applications The objective of the current study was to optimize the pretreatment conditions consisting of time, temperature and pH before freeze drying (FD) jackfruit bulb slices. The study investigate the effects of heat treatment on jackfruit bulb slices about residual polyphenol oxidase (PPO) activity, browning index, the content of vitamin C and texture change after FD. The study was conducted in order to get to the pretreatment conditions about FD jackfruit bulb crisps with low residual PPO activity, acceptable texture and best possible sensory attributes. In this paper, the pretreatment of FD jackfruit could provide guidance for other fruit processing.

Inhibitory effects of ultrasound combined with ascorbic acid or glutathione on enzymatic darkening of whole-wheat raw noodles

The effects of ultrasound combined with ascorbic acid or glutathione on the inactivation of polyphenol oxidase (PPO) in whole-wheat flour (WWF) and the prevention of enzymatic darkening of whole-wheat noodles (WWN) were studied. The residual PPO activity, free phenolics content, thermal properties, representative mineral elements, and B vitamins in WWF as well as the discoloration over 24 h, and textural characteristics of WWN after treatments were determined. The combination of ultrasound with ascorbic acid was proven to be the most effective treatment that reduced PPO activity in WWF and effectively prevented the enzymatic darkening of WWN. Moreover, the thermal properties, mineral element, and B vitamins in WWF, and the textural characteristics of WWN were little affected by ultrasound treatment and the two antioxidants. The results suggested that the combined treatments with ultrasound and antioxidants have exhibited significant effectiveness in maintaining the color stability and improving the overall quality of WWN.

The application of response surface methodology in studying the effect of heat and high hydrostatic pressure on anthocyanins, polyphenol oxidase, and peroxidase of mulberry (Morus nigra) juice

Mulberry juice is an excellent source of phytochemicals with medicinal properties. The effects of four independent variables (temperature, heating time, pressure, and pressurising time) on three response variables [% anthocyanin retained, and % residual activities of the enzymes polyphenol oxidase (PPO), and peroxidase (POD)] of mulberry juice were studied using response surface methodology. Mathematical models and optimum levels of the response variables were generated. Temperature had the greatest effect on all the response variables. The synergistic effect of temperature and pressure had significant effect (P < 0.05) on anthocyanin retained and residual PPO activity. The prediction of the desirability model, based on 95% confidence in the range of the independent variables, gave optimal treatment conditions of 83.39°C, 2.38 min, 480.00 MPa, and 21.67 min, respectively for temperature, heating time, pressure, and pressurising time. At these levels, the corresponding response variables were 91.68%, 44.69% and 20.17% for the amounts of anthocyanin retained, and residual activities of PPO and POD, respectively. The desirability index obtained was 0.741. The results were desirable and the mathematical models developed could be used to predict the outcome of the response variables to a high degree of accuracy.