Effect of High-Pressure Processing on Physical, Biochemical, and Microbiological Characteristics of Black Tiger Shrimp (Penaeus monodon)

The effect of high-pressure processing on quality and shelf life of black tiger shrimp was studied. Shrimp was high-pressure processed at selected pressure levels of 100, 270, and 435 MPa for 5 min at room temperature (25?±?2 °C). Changes in physical, biochemical, and microbiological characteristics after processing and during subsequent chilled storage were examined for 35 days. After processing significant (P?<?0.05) increase in moisture content and parallel reduction in protein content was observed. No significant changes were observed in TVB-N and TMA-N levels of shrimp after processing; however, these significantly increased with storage. Whiteness index increased with pressure intensity imparting brighter and mildly cooked appearance. Pressure-induced hardening effect was observed, which showed decreasing trend during storage. The treated samples maintained lower viable counts throughout the storage, thus having better microbial quality than untreated sample. Shelf life was extended to 15 days in shrimp treated at 435 MPa compared with 5 days in untreated sample. Pressure treatment of 435 MPa was found to be most effective in preserving the quality and extending the shelf life of black tiger shrimp.     

Combined Effect of Chitosan and Oregano Essential Oil Dip on the Microbiological, Chemical, and Sensory Attributes of Red Porgy (Pagrus pagrus) Stored in Ice

The combined effect of chitosan and oregano essential oil dip on shelf life of whole red porgy (Pagrus pagrus) stored in ice under refrigeration was investigated for a period up to 20 days. Quality attributes monitored during storage included microbiological (total viable counts, Pseudomonas spp., H₂S-producing bacteria including Shewanella putrefaciens, Enterobacteriaceae, and lactic acid bacteria), physicochemical (pH, thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), trimethylamine (TMA), and color), and sensory (odor and taste) parameters. Untreated red porgy was used as the control sample. Regarding the chemical indicators of spoilage, TBARS values for all treatments were equal to or less than 0.4 mg MDA?kg^?1 throughout the 20-day storage period. pH values varied between 6.6 (day 0) and 6.9 (day 14) for the various treatments. TVB-N values increased gradually during storage reaching the proposed acceptability limit (30 mg N?100 g^?1) on day 13 for control samples, days 15–16 for samples treated with oregano essential oil, day 20 for samples treated with chitosan, and >20 days for samples treated with chitosan plus oregano essential oil. Likewise, TMA values reached the proposed limit (5–6 mg N?100 g^?1) for red porgy on days 11–12, 14–15, 19–20, and >20, respectively. Finally, sensory evaluation data were in general agreement with microbiological data indicating a product shelf life of ca. 11 days for control samples, 16 days for samples treated with oregano essential oil, 18 days for samples treated with chitosan, and 19–20 days for samples treated with chitosan plus oregano essential oil.     

Effect of High Hydrostatic Pressure Treatment (HHPT) on Quality and Shelf Life of Atlantic Mackerel (Scomber scombrus)

The ability of high hydrostatic pressure treatment (HHPT) to extend the shelf life of Atlantic mackerel (Scomber scombrus) was assessed in this study. For that purpose, fillets were subjected to pressure treatments at 200, 300, 400 MPa at 5, 10, 15 °C for 5 and 15 min. The influence of pressure treatments on the levels of trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) as well as color changes was investigated. The suitable combinations were determined as 200 MPa, 15 °C for 5 min. and 400 MPa, 5 °C for 5 min. In the second stage, the shelf life of samples, which were treated at these conditions, stored at 4?±?0.5 °C were studied by monitoring pH, color, sensorial features (appearance and odor), TMA-N, TBA, total volatile basic nitrogen, histamine, and total mesophilic aerobic count. The unpressurized mackerel samples were acceptable up to only 7 days compared to 17 and 19 days after 200 and 400 MPa treatments; respectively. The results obtained in this study showed that HHPT in combination with chilled storage can improve the shelf life and quality of fish.     

Correlation Between Electrical Conductivity of the Gutted Fish Body and the Quality of Bighead Carp (Aristichthys nobilis) Heads Stored at 0 and 3 °C

The changes in impedance change ratio (Q value), pH value, texture, K value, total volatile basic nitrogen (TVB-N), total aerobic count (TAC), drip loss, and sensory assessment (SA) of bighead carp (Aristichthys nobilis) during 0 and 3 °C storage were investigated. Simultaneously, correlation models were developed by analyzing the correlation between the measured values. The results indicate that during postmortem storage, Q value is significantly (p?<?0.05) related to pH value and texture indexes (hardness, adhesiveness, springiness, cohesiveness, and resilience); during long-term storage, SA exceeds the acceptable limit on the 15th day at 0 °C and the 12th day at 3 °C, while K value, TVB-N, TAC, and drip loss increase to 72.4 %, 18.9 mg/100 g, 4.82 log₁₀ cfu/g, and 7.09 % at 0 °C, and 78.5 %, 14.0 mg/100 g, 4.97 log₁₀ cfu/g, and 5.08 % at 3 °C, respectively. Meanwhile, Q value declines to 18.9 % at 0 °C and 12.7 % at 3 °C. The correlation coefficients between Q and K values, TVB-N, TAC, drip loss, and SA are 0.955, 0.964, 0.966, 0.965, and 0.994 at 0 °C, and 0.969, 0.967, 0.979, 0.960, and 0.996 at 3 °C, respectively, indicating significant linear relationships (p?<?0.05). Therefore, Q value can be used as a fast nondestructive method to estimate the quality of bighead carp heads during storage at 0 and 3 °C.     

Changes in Quality Attributes During Storage of High-Pressure and Thermally Processed Pineapple Puree

The primary issue of the pineapple puree processing industry is its limited stability. The study compares the quality changes in high-pressure and thermally processed pineapple puree at different storage conditions and estimates the shelf-life. The untreated (S1) and treated samples (S2, S3, and S4 treated at 600 MPa/50 °C/13 min, 600 MPa/70 °C/20 min, and 0.1 MPa/95 °C/12 min, respectively) packed in ethylene vinyl alcohol (EVOH) and multi-layered (ML) polyethylene terephthalate (PET) pouches were stored up to 125 days at 5, 15, and 25 °C. The total color change (?E*) and browning index during storage increased according to zero-order kinetic model, whereas ascorbic acid (AA), total phenolics, and total antioxidant capacity followed the first-order decay. The overall sensory acceptability (OA) of S2 was higher than both S3 and S4 at 5 °C, and it dropped rapidly at 15 and 25 °C. The activity of polyphenol oxidase and pectin methylesterase in S3 and S4 was less than 10 % up to 120 days at 5 °C. The consistency (κ) and residual enzyme activity in S2 decreased with storage duration and temperatures. For estimating the shelf-life, the change in OA was crucial for S2 and S3, whereas retention of AA served as the critical parameter for S4. The sample S2 packed in ML pouch was found to be the best sample having the shelf-life (microbial count?<?6-Log cfu g^?1, ?E*?<?12, OA?>?5, and AA?>?200 mg kg^?1) of 120, 50, and 25 days at 5, 15, and 25 °C, respectively.     

Optimisation of High Hydrostatic Pressure Processing of Pêra Rio Orange Juice

The influence of high hydrostatic pressure (HHP) on Pêra Rio orange juice was investigated using response surface methodology. A central composite design was used to evaluate the effects of three processing conditions (independent variables), namely pressure (100–600 MPa), temperature (30–60 °C) and time (30–360 s), on the native microflora and pectin methylesterase (PME) activity of orange juice. Analysis of variance showed that second-order polynomial models fitted well with the experimental data for PME residual activity (R ²?=?0.9586, p?<?0.001) and aerobic microorganism count (R ²?=?0.9879, p?<?0.001). The optimum HHP processing conditions to produce orange juice with PME residual activity of less than 20 % and low microorganism count (<2 log cycles CFU/mL) were 550 to 600 MPa, 55 to 60 °C and 330 to 360 s.     

Effects of High Pressure and Heat Treatments on Physicochemical and Gelation Properties of Rapeseed Protein Isolate

High pressure (HP, 200, 400, and 600 MPa)- and heat (60, 80, and 100 °C)-induced gelation, aggregation, and structural conformations of rapeseed protein isolate (RPI) were characterized using gel permeation–size-exclusion chromatography, differential scanning calorimetry, and circular dichroism (CD) techniques. HP treatments significantly (p?<?0.05) increased the content of soluble protein aggregates and surface hydrophobicity of RPI. In contrast, heat treatments at 80 and 100 °C led to significant (p?<?0.05) decreases in the amount of soluble protein aggregates. At pressure treatment of 200 MPa, there was a significant (p?<?0.05) increase in free sulfhydryl group content of RPI, whereas 400- and 600-MPa treatments as well as temperature treatments (60–100 °C) caused significant decreases. Protein denaturation temperature was increased by about 6 °C by HP and heat treatments. The far-UV CD spectra revealed increases in α-helix content of RPI after HP treatments with 400 MPa producing the most increase. Near-UV data showed that HP and heat treatments of RPI led to increasing interactions among the aromatic amino acids (evidence of protein aggregation), and between aromatic amino acids and the hydrophilic environment, which indicates protein unfolding. Least gelation concentration of RPI was significantly (p?<?0.05) reduced by HP and heat treatments, but HP-treated RPI produced gels with better textural properties (hardness increased from ~7.7 to 81.1 N, while springiness increased from ~0.37 to 0.99). Overall, pressure treatments (200–600 MPa) were better than heat treatments (60–100 °C) to modify the structure and improve gelation properties of RPI.     

Comparison of static and step-pulsed ultra-high pressure on the microbial stability of fresh cut pineapple

Fresh cut pineapple cubes inoculated with 10^4–5 CFU g⁻¹ Saccharomyces cerevisiae were packed in heat-sealed polyethylene pouches and subjected at ambient temperature to static and step-pulsed ultra-high pressure (UHP) treatments. Static treatments included 100 and 9000 s at 270 MPa and 9000 s at 340 MPa. Step-pulsed pressure treatments included 100, 300 and 600 s at 0–270 MPa using 0·5-s and 10-s pulses. Inoculated treated and untreated samples were held at 4°C for 60 days. Bacteria and yeast counts were determined using plate count agar and yeast extract peptone dextrose agar, respectively. Static treatment at 270 and 340 MPa for 9000 s resulted in <240 CFU g⁻¹ yeast and bacteria counts for up to 60 days. Step-pulsed pressure treatments for 100 s at 0–270 MPa using 0·5-s (200 pulses) and 10-s pulses (10 pulses) were more effective than a 100-s static 270-MPa treatment. Step-pulsed pressure treatments (300 and 600 s) using 0·5-s pulses (600 and 1200 pulses) and 10-s pulses (30 and 60 pulses) were as effective as 9000-s static pressure treatments at 270 and 340 MPa. This storage study confirmed the superiority of step-pulsed over static pressure treatments. © 1998 SCI.     

Effects of high pressure treatment on physicochemical characteristics of fresh sea bass (Dicentrarchus labrax)

The effects of high pressure (HP) treatment (pressure: 220–250–330 MPA; holding time: 5 and 10 min; temperature: 3, 7, 15 and 25°C) on physicochemical characteristics (colour, thiobarbituric acid, trimethylamine nitrogen values) of fresh sea bass fillets were investigated. HP-treated sea bass fillets had higher lightness (Hunter L*) values than untreated sea bass fillets; the magnitude of changes increased with treatment pressure. HP-induced changes in colour generally imparted a cooked sample. The TBA value of HP treated sea bass samples (except 220–330 MPa, 3°C for 5 min) were found to be insignificant (P > 0.05) or significantly (P < 0.05) lower than the untreated samples. TMA-N content of HP treated at 220–250–330 MPa, 3–7–25°C for 10 min sea bass samples were found to insignificant according to the untreated samples. The results obtained from this study showed that the quality of high pressure treated sea bass is best preserved at 220 MPa, 25°C for 5 min.     

Effect of pH on Enzyme Inactivation Kinetics in High-Pressure Processed Pineapple (Ananas comosus L.) Puree Using Response Surface Methodology

Effect of pH and high-pressure process treatments viz. pressure, temperature, and dwell time on inactivation of polyphenoloxidase (PPO), peroxidase (POD), bromelain (BRM), and pectinmethylesterase (PME) in pineapple puree was studied. Experiments were conducted according to rotatable central composite design (RCCD) within the range (?α to?+?α) of 100–600 MPa, 20–70 °C, and 0–30 min at three different pH levels (3.0, 3.5, and 4.0) followed by analysis through response surface methodology (RSM). Enzyme inactivation was significantly (p?k in min^?1) revealed that PPO was the most resistive (k ranged between 0.0020 and 0.0379 min^?1) when compared with other three enzymes within the experimental domain. Increased k at lower pH with constant pressure and temperature depicted that pH had negative effect on the inactivation process. The optimized conditions targeting maximum inactivation of PPO, POD and PME with simultaneous retention of BRM in pineapple puree, were 600 MPa/60 °C/9 min, 600 MPa/60 °C/10 min and 600 MPa/60 °C/10 min for the samples of pH 3.0, 3.5, and 4.0, respectively.     

Effects of High-Pressure Processing on the Quality of Sea Bass (Dicentrarchus labrax) Fillets During Refrigerated Storage

The aim of this study was to evaluate the effect of high-pressure processing (HPP) on the quality of fresh sea bass fillets using two pressure levels (250 and 400 MPa; 5 min pressure holding time). Vacuum-packed fillets were used as control samples, and all fillets were stored under refrigerated conditions for 18 days. The microbiological, chemical, physical, and sensory parameters were followed. Both HPP treatments increased the microbiological shelf life of sea bass fillets. In day 14, control samples reached the upper acceptability limit (7 log colony-forming units (CFU)?g^?1), while fillets treated at 250 and 400 MPa had 3.2 and 1.4 log CFU g^?1, respectively. In general, hydrogen sulphide-producing bacteria and Enterobacteriaceae loads were below the detection limit in HPP treatments. Results from nucleotide analysis indicate that HPP treatments reduced the conversion of inosine 5′-monophosphate to inosine. HPP also influenced fillet sensory characteristics. The most evident changes in fillets were the increase in whiteness, the loss of translucency, and a firmer consistency. The effect was more pronounced in the treatment at 400 MPa. Lipid oxidation increased in HPP-treated samples, being more accentuated in the treatment at 400 MPa. Instrumental smell intensity increased in both HPP treatments, though the sensory panel did not detect any rancid or other unpleasant odours. No effect was observed in the amount of volatile bases or in pH values. In conclusion, HPP treatments showed potential application for new fish product development with increased microbiological safety and shelf life, longer freshness, and unique characteristics (e.g. firmer and whitish).     

Effect of Various Processing Methods on Quality of Mackerel (Scomber scombrus)

The effects of combinations of processes (hot smoking, marinating, vacuum packing and seasoning with dill (Anethum graveolens) on the quality parameters of mackerel (Scomber scombrus) stored at 4 °C were investigated in terms of sensory, chemical (total volatile basic nitrogen [TVB-N], thiobarbituric acid [TBA], peroxide value [PV], free fatty acids [FFA]) and microbiological parameters (total viable count [TVC], coliform, Escherichia coli, Staphylococcus aureus) during 9 months of storage. Sensory quality of smoked mackerel marinates with or without dill leaves (Group A, Group B, respectively) decreased throughout storage period. However, at the end of storage period, both the products were still acceptable by the panellist. At the beginning of storage, the initial TVB-N values were 24.14 mg/100 g and showed fluctuations during storage period. TBA values significantly increased (p?<?0.05) for both products during storage period. PV showed fluctuations. FFA increased gradually from 2.46 to 7.33 (expressed as % of oleic acid) for Group A and from 2.57 to 6.90 for Group B at the end of storage period. Coliform, E. coli and S. aureus were not detected during storage period. TVC remained lower than the acceptability limit of 10⁶ log CFU/g at the end of storage period. The results of this study suggest that shelf life of both products was 9 months and also the combination of hot smoking, marinating, vacuum packing and seasoning led to high-quality food item and was found to be effective in controlling the growth of bacteria and biochemical indices.     

Effect of Osmotic Dehydration Under High Hydrostatic Pressure on Microstructure, Functional Properties and Bioactive Compounds of Strawberry (Fragaria Vesca)

Sliced strawberries were subjected to combined osmotic dehydration (40 °Brix) and high hydrostatic pressure (HHP) at 100, 200, 300, 400 and 500 MPa for 10 min. This research was carried out to study the effects of pressure on firmness, polysaccharides, total dietary fibre and microstructure, functional properties (rehydration ratio and water holding capacity) and bioactive compounds (anthocyanins, flavonoid and total phenolic). HHP affected the texture of the fruits leading to soft fruits due to increasing pressure. Fruit microstructure evidenced influence of pressure presenting the pressurised samples irregular matrices compared to samples treated at 0.1 MPa (control samples). Polysaccharides increased with pressure. Total dietary fibre, anthocyanins, flavonoids and total phenolic content showed a decrease with pressure when compared to control samples. Based on results, minor alterations of the mentioned quality parameters were evidenced when working in the range of 300–500 MPa.     

Application of High Hydrostatic Pressure as a Pretreatment for Osmotic Dehydration of Banana Slices (Musa cavendishii) Finish-Dried by Dehumidified Air Drying

The process variables high hydrostatic pressure (HHP; 100–500 MPa), sucrose concentration (30–70 °Brix), immersion time (5–9 h) and immersion temperature (30–70 °C) were optimised to yield maximum water loss (WL), minimum solid gain (SG), minimum water activity (a _w) and minimum browning index (BI) during osmotic dehydration (OD) of banana slices (Musa cavendishii) pretreated by HHP using response surface methodology. The pressure-treated samples showed significantly higher WL and SG during OD (p?<?0.05), which was attributed to the rupture of cell wall with applied pressure, making the cells more permeable, also evident from the scanning electron micrographs of the banana tissue. The optimised operating conditions were: HHP of 200 MPa for a dwell time of 5 min at room temperature (26 °C), sucrose concentration of 60 °Brix, immersion time of 5 h and immersion temperature of 40 °C. A study of the concentration profiles during OD revealed no appreciable increase in SG and WL after 4 h; hence, immersion time was reduced to 4 h. The optimised product developed was dried to a moisture content of 15 % (wet basis) in a dehumidified air dryer at an air temperature of 40, 55 and 70 °C with a fixed air velocity of 3.8 m/s and relative humidity maintained at 20 %. The final dried product was analyzed for total soluble solids content, BI and a _w. A drying temperature of 55 °C was found to give superior quality OD banana slices in terms of reduced bulk, improved flavour, decreased a _w (<0.60), and reduced dehydration time and energy using HHP as a pretreatment.     

The impact of strawflower and mistletoe extract on quality properties of rainbow trout fillets

Many plants, including strawflower and mistletoe, contain antioxidants and antimicrobials, which can increase the shelf life of seafood. The main aim of this study was to investigate the effect of mistletoe and strawflower extracts at doses of 0.5% (w/v) on the sensory, chemical and microbiological properties of rainbow trout fillets during 27 days of storage at 2 ± 1 °C. The phenolic compounds in these plants have been studied, but their effects on food quality and storage properties have not been reported. We found that extract of mistletoe did not extend the shelf life of the fillets; however, the strawflower extract show high antimicrobial activity in fish fillets. The shelf life of rainbow trout was 20 days for the control and fish treated with mistletoe extract and 23 days for fish treated with strawflower extract. The antioxidant effect of extracts on fish fillets was weak, whereas strawflower extract had high antimicrobial effect. Peroxide value (PV) and thiobarbituric acid (TBA) values fluctuated during storage periods around main values below 14 meq O₂ kg^?1 and 0.6 MA kg^?1, respectively. Putrescine, cadaverine, spermine, spermidine, serotonin, tyramine and dopamine were main amine, whereas histamine accumulated at low levels (<2 mg per 100 g). Strawflower suppressed biogenic amine accumulation in fish fillets. At the limit of acceptability, total viable count (TVC), Enterobacteriaceae and lactic acid bacteria count remained below 7.6, 6.83 and 8.01 log CFU g^?1, respectively. The results of this study show that ethanol extracts of strawflower improve the shelf life of rainbow trout.     

High-Pressure Processing for the Control of Lipolysis,Volatile Compounds and Off-odours in Raw Milk Cheese

Build-up of flavour compounds throughout ripening of raw milk cheeses may result in strong over-ripening notes during refrigerated storage. In order to control the formation of free fatty acids (FFAs) and volatile compounds, and the appearance of off-odours, raw milk cheeses were high-pressure-processed (HPP) 21 or 35 days after manufacture at 400 or 600 MPa. Ripening proceeded at 8 °C until day 60 and, afterwards, cheeses were held at 4 °C until day 240. The effect of HPP on the formation of FFAs and volatile compounds was dependent on pressure level and cheese age at the time of treatment. On day 60, acetic and propionic acids, branched-chain FFAs and short-chain FFAs showed the lowest (p?<?0.05) concentrations in cheeses treated at 400 or 600 MPa on day 21, while medium- and long-chain FFAs were at similar levels in all cheeses. HPP influenced significantly (p?<?0.05) 84 out of the 94 volatile compounds found in cheese. On day 60, the lowest (p?<?0.05) concentrations of acids, alcohols and esters were recorded for cheeses treated at 400 or 600 MPa on day 21, and the lowest (p?<?0.05) concentrations of ketones for cheeses treated at 400 MPa on days 21 or 35. On day 240, all HPP cheeses showed lower (p?<?0.05) concentrations of aldehydes, esters and, particularly, sulphur compounds than control cheese, which exhibited putrid and rancid off-odours from day 120 onwards. Principal component analysis combining FFAs and volatile compounds discriminated 240-day control cheese from 120-day control cheese and both from the rest of cheeses.     

Influence of packaging strategy on microbiological and biochemical changes in high‐pressure‐treated oysters (Crassostrea gigas)

BACKGROUND: High‐pressure (HP) treatment is being increasingly employed for commercial processing of oysters, but there is relatively limited information on the microbiological quality and enzymatic activity of HP‐treated in‐shell oysters. The objective of this research was to study the influence of packaging strategy on microbiological and biochemical changes in oysters HP treated at 260 MPa for 3 min or 400 MPa for 5 min at 20 °C and stored at 0 °C either aerobically on ice, in vacuum packaging (VP) or under modified atmosphere packaging (MAP; 40% CO₂, 60% N₂), compared with changes in untreated oysters. RESULTS: Both HP treatments reduced the microbiological load to below the detection limit (<100 colony‐forming units g^?1). MAP and VP also delayed subsequent microbial growth compared with aerobically stored samples. After 21 days of storage, total volatile base levels remained lower than the proposed acceptability limits for all samples; however, after 28 days, only oysters HP treated at 400 MPa, irrespective of the packaging system used, did not exceed this limit. HP increased the thiobarbituric acid‐reactive substance (TBARS) values of oysters, indicating increased lipid oxidation. During storage, TBARS values of all MAP and VP oysters remained lower than those of aerobically stored oysters. CONCLUSION: HP treatment, in combination with adequate chilled storage and MAP, can extend the shelf‐life and safety of oysters. Copyright © 2008 Society of Chemical Industry     

The Effects of High-Pressure Processing at Low and Subzero Temperatures on Inactivation of Microorganisms in Frozen and Unfrozen Beef Mince Inoculated with Escherichia coli Strain ATCC 25922

Frozen and unfrozen beef mince inoculated with Escherichia coli strain ATCC 25922 were exposed to a pressure of 300 MPa for 5 min at different temperatures (?10, ?5, 0, 10 and 20 °C). A maximum reduction of 1.5 log in total aerobic count (TAC) was obtained in unfrozen samples at ?5 °C, whereas at 20 °C, the reduction was only 0.6 log. Microbial inactivation in beef mince was enhanced by freezing the beef mince prior to pressurization. An average log reduction of 3.0 (SD?=?0.2) in both E. coli and TAC was obtained in frozen beef mince treated at ?5 °C. The highest bacterial reductions were observed in frozen samples. The extent of bacterial injury was substantially less in frozen samples than unfrozen samples, indicating that the damage inflicted on microorganisms in frozen beef mince by high pressure was irreversible. Lightness (L ^*), redness (a ^*) and yellowness (b ^*) values measured in accordance of Commission Internationale de l’Eclairage (CIE) for all the pressure-treated frozen and unfrozen samples differed slightly from unfrozen control samples (average total colour change, ΔE?=?6.1, SD?=?1.1). Water-holding capacity (WHC) measured by “high-pressure expressed moisture”, a new method proposed in this study, showed that freezing the samples prior to pressurization could increase WHC of minced beef. The results suggest that high-pressure processing could be used to make safer traditional raw minced meat products, such as steak tartare and cig kofte, a traditional Turkish dish made with minced beef, bulgur and spices.     

Stability and Quality Parameters of Probiotic Cantaloupe Melon Juice Produced with Sonicated Juice

The use of sonicated melon juice as substrate for Lactobacillus casei growth in cantaloupe melon juice and its effect on product quality were investigated. The survival of L. casei in the fermented juice, the product color, the post-acidification and other quality parameters were evaluated in the refrigerated product (4 °C) for a period of 42 days. Storage pH, color, sugar content, lactic acid concentration, biomass and viable cells count were determined. The caloric value of the product was also evaluated. During the refrigerated storage period, acidification and a slight reduction in the number of viable cells were observed. However, a sufficient number of viable cells were observed to guarantee the beneficial properties from probiotic consumption (>8 log CFU?ml^?1) throughout the storage period, for both stocked samples (with and without sugar addition). The product color was also preserved during storage. The developed product resulted in a low caloric product. The caloric value was reduced during the storage period due to sugar consumption by the remaining microorganisms.     

A Comparison Between E-Beam Irradiation and High-Pressure Treatment for Cold-Smoked Salmon Sanitation: Shelf-Life, Colour, Texture and Sensory Characteristics

The effect of electron beam irradiation and high-pressure treatment on the characteristics of cold-smoked salmon during refrigerated storage at 5 °C was investigated. Irradiation at 1–4 kGy and high-pressure treatments at 450 MPa for 5–25 min reduced total viable counts and delayed microbial growth. Irradiation induced a slight decrease in redness (a*), whereas high-pressure treatment resulted in a brighter (L*) appearance of smoked salmon. Higher values of hardness and shear strength were recorded for pressurized samples. Total biogenic amine concentration in smoked salmon held for 20 days at 5 °C was lowered by 81 % in samples irradiated at 2 kGy, and by 46 % in samples pressurized at 450 MPa for 25 min. Smoked salmon irradiated at 1 or 2 kGy had negligible sensory (appearance, odour and flavour) alterations, but lower sensory preferences in the rank order test were observed for 3 and 4 kGy samples. Pressurization for 5 min at 450 MPa induced moderate sensory changes, which were more marked after 15 or 25 min at 450 MPa. These results point to the usefulness of E-beam radiation at 1.5 kGy to assure a safe product of sensory characteristics similar to those of untreated smoked salmon.