High pressure and thermal inactivation kinetics of polyphenol oxidase and peroxidase in strawberry puree

The objective of this work was to study the thermal and high pressure inactivation kinetics of polyphenol oxidase (PPO) and peroxidase (POD) in strawberry puree. PPO from two strawberry cultivars (‘Festival’ and ‘Aroma’) was found to be highly thermostable in strawberry puree with no significant inactivation even after 30 min treatment at 100 °C. In contrast, POD from the two cultivars displayed very high thermosensitivity with complete inactivation in less than 5 min at 70 °C. The thermal inactivation kinetics of strawberry POD was described by a biphasic model. The activation energies for the inactivation of the stable and the labile fractions were estimated to be 254.9 and 221.6 kJ/mol respectively. Combined high pressure–thermal treatment at pressures ranging from 100 to 690 MPa, temperatures ranging from 24 to 90 °C and treatment times between 5 and 15 min did not have significant effect on PPO while substantial inactivation of POD was observed. The inactivation kinetics of POD during combined high pressure–thermal processing was well described by first-order kinetics probably due to the inactivation of the labile fraction during the pre-heating and the compression phase.Industrial relevanceThe oxidative enzymes polyphenol oxidase and peroxidase cause the degradation of anthocyanins and other polyphenols in strawberry products, leading to discoloration and loss of antioxidant activity. In this work the thermal and high pressure inactivation of strawberry polyphenol oxidase and peroxidase was investigated so as to assess the suitability of high pressure processing as an alternative to thermal processing. Strawberry polyphenol oxidase was found to be highly resistant to both thermal and high pressure inactivation. Thus in order to maintain the quality of processed strawberry products, high pressure processing should be accompanied by additional measures such as exclusion of oxygen, refrigerated storage and the use of natural enzyme inhibitors.     

High pressure processing of cocoyam,Peruvian carrot and sweet potato: Effect on oxidative enzymes and impact in the tuber color

High pressure processing (HPP) is a non-thermal technology used to activate or inactivate enzymes. This study investigated the effects of HPP (600 MPa for 5 or 30 min at 25 °C) on cocoyam, Peruvian carrot and sweet potato color, and the polyphenoloxidase (PPO) and peroxidase (POD) activities in tuber cubes, puree, and enzyme extract subjected to HPP. The results showed enzyme inactivation by HPP in cocoyam (up to 55% PPO inactivation in puree and 81% POD inactivation in extract) and Peruvian carrot (up to 100% PPO and 57% POD inactivation the extract). In contrast, enzyme activation was observed in sweet potato (up to 368% PPO and 27% POD activation in puree). The color results were compatible to enzyme activity: the color parameters remained unchanged in cocoyam and Peruvian carrot, which showed high PPO and POD inactivation after HPP. Furthermore, the impact of HPP on the enzymes was influenced by the matrix in which HPP was carried out, evidencing that the enzyme structure can be protected in the presence of other food constituents.Industrial relevanceThe enzymes PPO and POD are an important concern for vegetable processing, due its ability to induce browning after vegetables are cut. The HPP at 600 MPa for 5 or 30 min can be used to inactivate these enzymes in cocoyam and Peruvian carrot, guaranteeing the color and freshness of the tubers similar to the fresh cut vegetable.     

Influence of ohmic heating/osmotic dehydration treatments on polyphenoloxidase inactivation,physical properties and microbial stability of apples (cv. Granny Smith)

The combined effect of ohmic heating (OH) and osmotic dehydration (OD) with vacuum impregnation (VI), on the polyphenoloxidase (PPO) inactivation, physical properties and microbial stability of apples stored at 5 °C or 10 °C was analyzed. The treatments were performed using a 65% (w/w) sucrose solution and with ohmic heating at 13 V/cm at 30 °C, 40 °C or 50 °C for 90 min. Examination of the dehydrated samples showed that the water loss and the solid gain were greater with the OD/OH and VI/OH treatments at 50 °C. PPO was completely inactivated by the OD/OH and VI/OH treatments at 50 °C. There was a correlation between the PPO activity, the color change and the browning index of the treated and stored samples; the values for these parameters were stable when PPO was inactivated. The lowest loss of firmness and color was obtained with the VI/OH treatment at 50 °C. The shelf-life of the apples treated with VI/OH at 50 °C and stored at 5 °C was extended to more than 4 weeks. Therefore, the VI/OH treatment at 50 °C was determined to be the best process for dehydrating apples.Industrial relevanceThe aim of this research was 1 to study the combined effect of ohmic heating (OH) and osmotic dehydration (OD) with vacuum impregnation (VI) on the polyphenoloxidase inactivation and microbial stability of osmotically dehydrated apples stored at either 5 °C or 10 °C. Two technologies, OH and OD were performed at 30, 40 or 50 °C with an electric field intensity of 13 V/cm and conventional heating for 90 min. The results showed a correlation between the PPO activity, the color change and the browning index of the treated and stored samples; the values were stable when PPO was inactivated. PPO was completely inactivated by the OD/OH and VI/OH treatments at 50 °C. The shelf-life of the apples treated was extended to more than 4 weeks. Under the investigated conditions, VI/OH treatment at 50 °C and stored at 5 °C may be considered the better minimal processing that preserves the fresh-like properties.     

Effect of high pressure thermal processing on some essential nutrients and immunological components present in breast milk

The influence of high pressure thermal (HPT) processing (300, 600 or 900 MPa at an initial temperature of 50, 65 or 80 °C, for 1 min) on the levels of tocopherols, fatty acids, cytokines, leukocytes and immunoglobulins (IgM, IgA and IgG) was evaluated in breast milk. Breast milk treated at 65 or 80 °C at any intensity of pressure caused a significant decrease in the content of α-tocopherol compared with untreated milk. The relative proportions of some important fatty acids were affected by HPT treatment. HPT processing had a minimal effect on the levels of some cytokines, such as IL-12, IL-17 and IFN-γ. Leukocytes viable cells did not survive to any of the treatments applied. Only the treatments at 300 MPa and 50 °C maintained certain levels of Igs such as IgM (~ 75% retention), IgA (~ 48%) and IgG (~ 100%), while the rest of combinations produced important decreases of their contents.Industrial relevanceHuman milk banks use low-temperature/long-time thermal pasteurisation for the preservation of milk and to avoid risks of infections. Thermal treatment reduces nutritional and immunological properties of breast milk. The study of new methods to preserve milk quality could produce important benefits for the infants' receptor of milk. The application of high pressure processing at low temperatures has showed certain advantageous respect to the thermal treatment, however, the effect of high pressure at moderate-high temperatures have never been evaluated in breast milk.     

Combined high pressure-mild temperature processing for optimal retention of physical and nutritional quality of strawberries (Fragaria × ananassa)

Response surface methodology was used to determine the optimal high pressure-temperature condition for the processing of strawberries for maximal inactivation of oxidative enzymes as well as best retention of nutritional and physicochemical quality following processing and during storage. High pressure treatment at 20–40 °C resulted in visual quality closest to the fresh product. High pressure combined with mild temperature caused substantial inactivation of peroxidase in strawberries with a maximum of 58% inactivation after 10 min treatment at 600 MPa and 60 °C. No significant inactivation of polyphenol oxidase was observed in strawberries under the studied condition. Combined high pressure-mild temperature processing did not have significant effect on the total polyphenol and total anthocyanin content of strawberries. However, an average of 22 ± 13% loss of total polyphenol content and 27 ± 10% loss of total anthocyanin contents was observed after 3 months of refrigerated storage.Industrial relevanceThe work described in this research is relevant to the high pressure processing of strawberries and other berry fruits. The results of the study have shown that best quality retention of strawberry products is obtained when high pressure processing is combined with vacuum packaging in high barrier packaging material and refrigerated storage since strawberry polyphenol oxidase is highly resistant to high pressure inactivation.     

Peroxidase (POD) and polyphenol oxidase (PPO) photo-inactivation in a coconut water model solution using ultraviolet (UV)

The interest in coconut water as a beverage is increasing due, not only to its sensory properties, but also to its nutritional characteristics. Even so, several challenges limit its processing, the inactivation of the polyphenol oxidase (PPO) and peroxidase (POD) enzymes being the most important. Although the inactivation of these enzymes has been extensively studied in coconut water, both by conventional and emerging technologies, the technologies evaluated so far are either not effective in the inactivation of these enzymes and/or result in undesirable changes. This work evaluated the photo-inactivation of POD and PPO in a coconut water model solution using ultraviolet radiation (UV). Both enzymes showed continuous inactivation behaviour in relation to the processing time, this being described by a two-portion inactivation kinetics. A possible mechanism for the observed photo-inactivation was proposed, involving steps of molecular unfolding and aggregation. The POD activity after 15 min of processing was ~ 5% of its original value, and reduced to ~ 1% after 30 min of UV processing. After 15 min of processing, PPO activity was ~ 8% of its original value, falling to ~ 2% after 30 min of UV processing. The results obtained highlight the potential use of the ultraviolet radiation to inactivate both enzymes in coconut water.     

Inactivation of polyphenol oxidase in muscadine grape juice by dense phase-CO2 processing

The effect of dense phase-CO₂ processing (DP-CO₂) on polyphenol oxidase (PPO) activity, polyphenolic and antioxidant changes in muscadine grape juice under different processing pressures (27.6, 38.3, and 48.3 MPa) and CO₂ concentrations (0, 7.5, and 15%) were measured. Subsequently two DP-CO₂ conditions (48.3 MPa at 0 or 15% CO₂) were evaluated for polyphenolic and antioxidant changes during storage (4 °C, four weeks). Pressure alone was responsible for a 40% decrease in PPO activity that resulted in 16–40% polyphenolic and antioxidant losses. Increasing CO₂ from 0 to 7.5% was responsible for an additional 35% decrease in enzyme activity and a two-fold greater polyphenolic retention. However, insignificant changes in PPO activity or polyphenolic retention were observed when CO₂ was increased to 15%. During storage, juices with residual PPO activity following processing resulted in greater polyphenolic (8- to 10-fold) and antioxidant capacity (four-fold) degradation compared to control juices with no PPO activity. This study demonstrated that partial PPO inactivation can be obtained by DP-CO₂ and that CO₂ level was the primary variable influencing PPO activity and polyphenolics and antioxidant capacity retention in muscadine grape juice.     

Calcium lactate washing treatments for salad-cut Iceberg lettuce: Effect of temperature and concentration on quality retention parameters

Salad-cut lettuce was washed in calcium lactate solution at different concentrations (0.5%, 1.5% and 3%) and temperatures (4, 25 and 50 °C) for a period of 1 min. The treated salad-cut lettuce was packaged and stored at 4 °C for 10 days. Markers of quality retention: colour, texture, browning, texture related enzymes and sensory properties, were analysed during storage. The use of high temperatures (50 °C) showed a positive effect on enzymes related to quality maintenance. It reduced the activity of the browning-related enzymes polyphenol oxidase and peroxidase but it increased the activity of pectin methyl esterase, an enzyme involved in the maintenance of texture. High calcium lactate concentrations (3%) produced a reduction in the respiration rate of the salad-cut lettuce during storage, but also a loss of luminosity and greenness (a*). The use of high temperatures and intermediate calcium lactate concentrations (1.5%) proved to be the best washing treatment to maintain the quality of salad-cut lettuce over 10 days storage. These conditions (50 °C and 1.5% calcium lactate) gave higher freshness scores and lower browning scores than conventional chlorine treatment when evaluated by a sensory panel.     

High pressure thermal processing for the inactivation of Clostridium perfringens spores in beef slurry

The spores of Clostridium perfringens can survive and grow in cooked/pasteurized meat, especially during the cooling of large portions. In this study, 600 MPa high pressure thermal processing (HPTP) at 75 °C for the inactivation of C. perfringens spores was compared with 75 °C thermal processing alone. The HPTP enhanced the inactivation of C. perfringens spores in beef slurry, resulting in 2.2 log reductions for HPTP vs. no reductions for thermal processing after 20 min. Then, the HPTP resistance of two C. perfringens spore strains in beef slurry at 600 MPa was compared and modeled, and the effect of temperature investigated. The NZRM 898 and NZRM 2621 exhibited similar resistance, and Weibull modeled well the log spore survivor curves. The spore inactivation increased when HPTP temperature was raised from 38 to 75 °C. The results confirm the advantage of high pressure technology to increase the thermal inactivation of C. perfringens spores in beef slurry.Industrial relevanceC. perfringens spores may cause food/meat poisoning as a result of improperly handled and prepared foods in industrial kitchens. Thermal processes at 100 °C or higher are generally carried out to ensure the elimination of these pathogenic spores. High pressure processing (HPP) is a food pasteurization technique which would help to maintain the sensorial and nutritional properties of food. Preservation of foods with HPP in conjunction with mild heat (HPTP) would enhance the spore inactivation compared to thermal processing alone at the same temperature, due to a known germination–inactivation mechanism. This technology, together with the application of Good Manufacturing Practices, including rapid cooling, is a good alternative to the traditional methods for producing safe processed meat and poultry products with enhanced sensory and nutritional quality.     

Effects of high hydrostatic pressure on the quality and shelf-life of jujube (Ziziphus jujuba Mill.) pulp

This study evaluated the effects of high hydrostatic pressure (HHP) on the microbial counts, physicochemical properties, bioactive compounds, and antioxidant capacity of jujube pulp. Additionally, this study compared the shelf life of jujube pulp following HHP (600 MPa/20 min) and thermal treatment (100 °C/10 min) during 40 days of storage at 4 °C and 15 °C. The microbial count of HHP-treated jujube pulp (≥ 400 MPa/20 min) was below the detection limit. Total soluble solids and total sugars were not significantly affected by HHP processing, and > 90% ascorbic acid was retained in HHP-treated samples. HHP slightly reduced pH and browning degree and increased total phenolic content, flavonoid content, and antioxidant capacity. HHP can be used as an alternative to thermal pasteurization of freshly squeezed jujube pulp.Industrial relevanceEffects of high hydrostatic pressure (HHP) processing and thermal treatment (TT) on microbiological quality, physicochemical properties, bioactive compounds and antioxidant activity in jujube pulp were investigated. Greater inhibition of microorganisms and better retention of ascorbic acid, total phenolics, flavonoid and antioxidant capacity were observed after HHP-treatment. The available data could be used to design the HHP parameters for high quality jujube juice. Further, this research would provide a useful method for preservation of jujube products and potential technical support for jujube commercial production.     

Study of lipoxygenase and peroxidase as blanching indicator enzymes in peas: change of enzyme activity,ascorbic acid and chlorophylls during frozen storage

In this study, the effects of different blanching conditions on residual lipoxygenase (LOX) and peroxidase (POD) activities and quality changes in peas during frozen storage were studied. Peas were analysed for LOX and POD activities, ascorbic acid and chlorophylls a and b contents at 1, 2, 3, 6, 9 and 12 months of frozen storage. No regeneration of LOX and POD activities was determined in frozen-stored peas at −18 °C. The degradations of ascorbic acid and chlorophylls followed first-order kinetics. The half-lives of ascorbic acid, chlorophylls a and b derivatives in unblanched peas were found to be 3.30, 14.01 and 36.76 months during storage, respectively. Blanching at both 70 °C for 4.0 min and 80 °C for 2.0 min increased the half-life of ascorbic acid while it decreased those of chlorophylls a and b. Overall results suggested a blanching time of 2.0 min at 80 °C to inactivate 90% of initial POD activity, so, to retain quality parameters such as ascorbic acid and chlorophyll pigments in a storage period of 12 months at −18 °C.     

Effects of chitosan coating on shelf life of cold-stored litchi fruit at ambient temperature

Postharvest pericarp browning of litchi fruit results in an accelerated loss in shelf life and a reduced commercial value. Visual quality was lost in only 6 h at ambient temperature when fruit were removed from storage at 2 °C, due to browning. The experiment was conducted to test the role of chitosan coating in inhibiting skin browning and extending shelf life of cold-stored litchi fruit at ambient temperature. Litchi fruit were treated with 2 g chitosan/100 g solution and then stored for 20 days at 2 °C and 90–95% relative humidity (RH), prior to shelf life evaluation at 25 °C and 80–90% RH. Changes in polyphenol oxidase (PPO) activity, anthocyanin concentration, colour index, eating quality and concentrations of total soluble solids and titratable acidity were measured. The effects of chitosan coating on disease incidence were also evaluated. Application of chitosan coating delayed the decrease in anthocyanin content, the increase in PPO activity and the changes in colour index and eating quality, reduced the decrease in concentrations of total soluble solids and titratable acidity, and partially inhibited decay. The results suggested that treatment with chitosan coating exhibited a potential for shelf life extension at ambient temperature when litchi fruit were removed from cold storage.     

Effect of high pressure thermal processing on the quality attributes of Aloe vera-litchi mixed beverage

Sensory evaluation of four different formulations of Aloe vera-litchi mixed fruit beverage (ALMB) was carried out by a semi-trained sensory panel, and the corresponding sensory data was considered for similarity analysis using fuzzy logic. Based on the similarity analysis, the optimum formulation of ALMB was selected with litchi juice (85%):Aloe vera juice (15%, v/v). Further, the effect of high pressure thermal processing (HPTP) on the quality attributes namely physicochemical, nutritional, enzyme activity and the microbial population was evaluated within the domain of 400–600 MPa/30–60 °C/0–15 min as processing condition. The physicochemical properties such as pH, TSS and acidity of ALMB were minimally affected by HPTP, whereas, the loss of ascorbic acid up to 40% and the natural color of the ALMB samples was affected. The increased extractability of phenolics and antioxidants was observed for the samples treated at all the pressures and temperature up to 50 °C. Pectinmethylesterase (PME) was found to be the most baro-resistant enzyme with the maximum inactivation of up to 54% followed by peroxidase (POD) (72%) and polyphenoloxidase (PPO) (82%). The microbial inactivation during the isobaric period was well described by the first-order model (R² > 0.82); yeast and mold group was found to be the most baro-resistant among the entire studied natural microflora.Industrial relevanceThe present study gives information on fuzzy logic based similarity analysis technique for ranking of different fruit based formulation as well as ranking of its quality attributes. This technique can be used by the industry to process the linguistic data of sensory analysis and make appropriate decisions for product development. High pressure thermal processing can be efficiently used to develop high quality beverage products.     

Colour and texture of apples high pressure processed in pineapple juice

Cubes of Granny Smith and Pink Lady apples were vacuum packed in barrier bags with 0% to 50% (v/v) pineapple juice (PJ) at 20°Bx and subjected to high pressure processing (HPP) at 600 MPa for 1–5 min (22 °C). The in-pack total colour change (ΔE) was observed over 4 weeks at 4 °C. Within <1 week of storage at 4 °C, texture, polyphenoloxidase, pectinmethylesterase activities, changes in ΔE and visual browning after opening the bags during air exposure (22 °C; 21% O2 ) for 5 h were also monitored. During the 4 weeks storage in bag visible colour changes were not observed. Texture and ΔE after 5 h air exposure were significantly affected by the apple variety, HPP time and % PJ used. The combined treatment significantly reduced residual PPO activity while PME activity was not affected in both varieties. Pineapple juice in combination with HPP could be used as a natural preservation system for minimally processed apples.Industrial relevanceBrowning upon opening the packs and during air exposure can adversely affect the quality of fresh-cut fruits. Combined treatment of high pressure processing (HPP) and use of pineapple juice has the potential to prevent browning for several hours giving sufficient time for presentation and use in domestic and foodservice environment where high quality fresh-like fruit is required.     

Evaluation of seaweed extracts functionality as post-harvest treatment for minimally processed Fuji apples

The potential application of Fucus spiralis, Bifurcaria bifurcata, Codium tomentosum and Codium vermilara extracts as post-harvest treatments in minimally processed (MP) Fuji apple was investigated. 0.5% solutions of each extract were applied to MP Fuji apple and its effect on product quality was assessed over 20 days of storage at 4 ± 2 °C in terms of moisture content, soluble solids concentration (SSC), firmness, browning index (BI) and POD and PPO activities. Application of Codium tomentosum extract resulted in a significant reduction in BI in comparison to all other tested treatments. POD and PPO activities were also significantly lower in MP apple treated with Codium tomentosum extract. These results identify Codium tomentosum extract functionality of reducing enzymatic browning, suggesting the potential application of this extract as a natural additive in MP fruit.Industrial relevanceThis study shows the advantages of using a novel post-harvest treatment based in edible seaweed extracts to preserve fresh-cut fruits, in particular Fuji apple. The results show clearly that this type of dipping treatment decreases browning index and inhibits enzymatic activities when compared with citric acid and control treatment (water). Codium tomentosum extract solution showed the highest efficacy, suggesting the potential application of this extract as a natural additive to be a substitute of chemicals used in food industry and its use has been restricted. This process is efficient, versatile and of simple implementation at the industrial level once the only change in the industrial process consists in the type of post-harvest solution treatment. Associated to the easy adaptation in the industrial process, the exponential development in aquaculture sector allows the obtention of this raw material in a sustained way. Extract functionality was attributed to its demarked inhibitory action on enzymatic activities of polyphenol oxidase and peroxidase, two major enzymes involved in enzymatic browning processes.     

Moisture sorption isotherms of high pressure treated fruit peels used as dietary fiber sources

High hydrostatic pressure (HHP) treatments can improve the potential of orange, mango, and prickly pear peels as food formulation fiber sources. Akaike Information Criteria differences identified Peleg and GAB as the best model alternatives to describe experimental moisture isotherms. HHP (600 MPa/10 min/22 and 55 °C) effects on moisture isotherms expressed as relative water sorption content change with respect to controls (RWSC_aw) showed that in the 0.1–0.93 a_w range, HHP improved the adsorption water retention of orange peels. The same was true for the desorption water retention for all HHP-treated fruit peels except for prickly pear HHP-treated at 22 °C and > 0.35 a_w. The area under the hysteresis curve (A_H) in the 0.15–0.51 a_w range showed that HHP increased hysteresis for all fruit peels tested. All this illustrates the HHP potential to modify the hygroscopic properties of fruit peels at lower temperature and in less processing time than conventional processes.Industrial relevanceOrange, mango, and prickly pear peels are potential food fiber formulation sources with differentiated hygroscopic and functional properties. In this study, 600 MPa treatments at 22 and 55 °C for 10 min modified the adsorption and desorption moisture retention capacity of all fruit peels tested in this study. HHP technology can improve the potential of fruit peels as dietary fiber sources with the advantage of shorter processing times and lower temperatures than conventional technologies used to treat food fibers.     

High-pressure and temperature effects on the inactivation of Bacillus amyloliquefaciens,alkaline phosphatase and storage stability of conjugated linoleic acid in milk

Milk rich in conjugated linoleic acid (CLA, 42 ± 3 mg g^− 1 fat) was used to evaluate the impact of high-pressure sterilization (HPS). The pressure, temperature and time needed to reduce 7-log of Bacillus amyloliquefaciens endospores were determined in the presence of nisin (4–64 mg L^− 1). In addition, the inactivation of alkaline phosphatase was evaluated. After HPS treatment, the remaining CLA and formation of hydroperoxides were monitored during storage up to 60 d at 25 °C. The addition of nisin (≥ 16 mg L^− 1) to milk significantly enhanced the inactivation of B. amyloliquefaciens (7-log reduction) after treatment at 600 MPa, 120 °C and 5 min of holding time. These conditions were selected to evaluate the impact of HPS on the CLA retention and hydroperoxides formation. Milk with the addition of nisin and treated with HPS delivered higher retention of CLA and a lower concentration of hydroperoxides compared with the UHT equivalent process (125 °C/15 s and 135 °C/10 s).Industrial relevanceHigh-pressure sterilization is a valuable alternative to produce superior quality milk products in cases where traditional thermal treatments have failed. This study evaluated the impact of processing conditions on the conjugated linoleic acid content at conditions where commercial sterilization has been achieved (7-log reduction of B. amyloliquefaciens). The outcomes of this study are considered as a step further for the development of high-pressure sterilized milk.     

UV-A light treatment for controlling enzymatic browning of fresh-cut fruits

Enzymatic browning is critical in the preservation of the quality and the shelf-life of fresh-cut fruits. Non-thermal technologies such as UV radiation are emerging for controlling polyphenol oxidase (PPO) activity, the main agent responsible for browning. After determining the best operational conditions of a UV LED illuminator (2.43 · 10^− 3 Wm^− 2 irradiance), the anti-browning effect of UV-A light (390 nm) treatment at 25 °C over increasing time periods up to 60 min was assessed on fresh-cut apples and pears. Color variation (ΔE) and its percent reduction (%RΔE) were measured using a colorimeter and the greatest effect was observed in apples which showed higher %RΔE values than pears (58% vs 25% after 60 min exposure, respectively). Anti-browning was found to be related to irradiance, exposure time and the fruit cultivar. Overall this study confirmed UV-A LED technology as an eco-friendly alternative to traditional approaches for reducing browning of minimally processed products.Industrial relevanceTreatment of fresh-cut products with UV-A LED is not only easy and inexpensive to produce but also presents few hazards for humans. Moreover, the use of LED light sources brings many advantages such as energy savings, device durability, low environmental impact, high luminous efficiency and little thermal effect. UV-A LED technology has great potential to meet the demands of the food industry in the processing of fresh-cut fruits and vegetables. In addition it could also be considered a pre-treatment of fruits and vegetables being processed for the production of snacks.     

Volatile profile of human milk subjected to high-pressure thermal processing

High pressure thermal (HPT) treatments consist of a combination of high pressure (500–900 MPa) and temperature (70–120 °C) over a short holding time. The rapid temperature increase during compression and temperature decrease in the product upon decompression could help to reduce the hardness of thermal effects encountered in conventional thermal technologies. The objective of this study was to evaluate the effect of HPT processing (300, 600 and 900 MPa combined with 50, 65 and 80 °C) on the profile of volatile compounds in breast milk. A total of 50 volatiles, belonging to 6 different chemical groups, were detected in milk samples. In general, HPT processing increased aldehydes, ketones, furans and pyrans, as well as alcohols, however, it did not modify the levels of carboxylic acids, and reduced the content of aliphatic hydrocarbons present in the non-treated human milk samples. HPT processing enhanced the total area content of volatile compounds derived from Maillard and lipid oxidation reactions, these changes being subjected to the intensity of pressure and temperature applied. Given that the levels of volatiles were significantly modified after the application of HPT processing, we can conclude that the range of the intensity of the treatments selected was not adequate to preserve the original profile of volatile compounds in breast milk.     

Fermented minced pepper by high pressure processing,high pressure processing with mild temperature and thermal pasteurization

High pressure processing (HPP) and thermal pasteurization (TP) of fermented minced pepper (FMP) were comparatively evaluated by examining their impacts on microbial load, titratable acid (TA), pH, a_w, firmness, color, capsanthin, ascorbic acid (AA), and biogenic amines (BAs) after processing and during 12 weeks of storage at 25 and 37 °C. The total plate count (TPC) in FMP samples was reduced by 1.48, 0.12 and 1.58 log₁₀ CFU/g after TP (83 °C/15 min), HPP1 (500 MPa/20 °C/5 min) and HPP2 (500 MPa/50 °C/5 min), respectively. The population of spores was reduced by 1.21 log₁₀ CFU/g only after HPP2. During storage at 25 or 37 °C, the TPC in TP, HPP1, and HPP2 samples increased by 0.88/1.21, 0.41/0.62 and 0.60/0.86 log₁₀ CFU/g, respectively, while the spores decreased below the detection limit. The retention of firmness after TP, HPP1 and HPP2 was 36.91, 91.15 and 66.48% respectively, and HPP-treated samples exhibited more retention during the storage. Color of FMP samples was not changed by TP, but slightly changed by HPP1 and HPP2. The content of capsanthin retained 78.99, 93.71 and 88.19% after TP, HPP1 and HPP2, it showed a small decrease during storage. Levels of biogenic amines (BAs) in HPP2 samples were lower than that of TP and HPP1 ones. There were better sensory quality and lower microbial level in HPP-treated samples during storage, indicating that HPP is a better choice for the preservation of FMP.Industrial relevanceConsumption of fermented minced pepper (FMP), as a traditional Chinese food, is becoming increasingly popular. Considering that heat treatment may destroy some heat-sensitive quality of the products, this study evaluated the effects of high pressure processing (HPP) on quality of FMP. Findings of this study could help processors commercialize HPP to replace current thermal processing in industrial production.