Effects of high hydrostatic pressure on structure and colour of red ginseng (Panax ginseng)

BACKGROUND: The conventional method of processing ginseng (Panax ginseng) roots into red ginseng involves mainly heating and drying processes. In the present study, this method was modified by using high hydrostatic pressure (HHP) to improve the physicochemical characteristics of red ginseng. RESULTS: The HHP process (600 MPa for 1 min) significantly improved the histological properties of red ginseng by increasing cellular disruption and release of cell contents. The total reducing sugar content was significantly (P < 0.05) higher (increased from 10.67 to 15.25 mg g^?1) in red ginseng processed at 600 MPa for 1 min. Similarly, the total free amino acid content also increased significantly (from 2.81 to 7.77 mg g^?1). The HHP process resulted in superior and more even colouration and gave an attractive visual appearance to red ginseng. The optical density at 420 nm and Hunter's colour a value (redness) of extracts prepared from red ginseng increased significantly (P < 0.05) with the application of HHP. CONCLUSION: HHP‐processed red ginseng has significantly higher reducing sugar and free amino acid contents together with a more compact cell structure and superior visual quality (brighter red colour). Hence the application of HHP in red ginseng processing can result in ginseng products of improved quality compared with those obtained by the conventional method. Copyright © 2012 Society of Chemical Industry     

超高压处理对复合苹果泥微生物和品质的影响

本研究以苹果、猕猴桃、胡萝卜为原料制备复合苹果泥,对不同配比的样品进行感官评价以确定最佳配比,并研究超高压(High Hydrostatic Pressure,HHP)处理参数(处理压力、保压时间)对样品微生物和品质的影响。通过感官评定确定苹果:猕猴桃:胡萝卜最佳配比为6:2:1,通过筛选确定超高压杀菌参数为400 MPa/2 min和500 MPa/2 min。结果表明,HHP样品的可溶性固形物、膳食纤维、总类胡萝卜素和β-胡萝卜素含量与热处理之间没有显著性差异(P>0.05);HHP样品具有更好的色泽和更高的抗坏血酸含量及抗氧化能力,其中抗坏血酸含量在0.75~0.83 mg/100 g,而热处理仅为0.55 mg/100 g;同时HHP样品黏度更高,表面积平均粒径更小。超高压处理对样品中多酚氧化酶(Polyphenol Oxidase,PPO)和果胶甲酯酶(Pectin Methylesterase,PME)的钝化能力比热处理弱,残存酶活分别为56.70%~65.54%和82.08%~86.91%,而热处理则为38.04%和81.89%。因此超高压处理能够更好地保证复合苹果泥的理化特性和营养品质,但对酶活的钝化能力不强。     

Comparison of Microbial Inactivation and Rheological Characteristics of Mango Pulp after High Hydrostatic Pressure Treatment and High Temperature Short Time Treatment

The effects of high hydrostatic pressure (HHP) treatments at pressures of 300–600 MPa for 1–20 min and of high-temperature, short-time (HTST) treatment on the inactivation of natural microorganisms in blanched mango pulp (BMP) and unblanched mango pulp (UBMP) were investigated. No yeasts, molds, or aerobic bacteria were detected in BMP or UBMP after HHP treatments at 300 MPa/15 min, 400 MPa/5 min, 500 MPa/2.5 min, and 600 MPa/1 min and HTST treatment at 110 °C/8.6 s. Therefore, these conditions were selected to study the effects of HHP and HTST treatments on pectin methylesterase (PME) activity, water-soluble pectin (WSP) levels, and the rheological characteristics of UBMP and BMP. HHP treatment at a pressure of 600 MPa for 1 min significantly reduced PME activity in UBMP and significantly activated PME in BMP, whereas pressures of 300–500 MPa activated PME regardless of blanching. However, PME activity was reduced by 97 % in UBMP and was completely inactivated in BMP by HTST treatment. WSP levels were significantly decreased by HHP treatment but were increased by HTST treatment in UBMP and BMP. Both HHP and HTST treatments increased the viscosity, storage modulus, and loss modulus of UBMP and BMP. No significant changes in total sugar, total soluble solids, titratable acid, or pH were found after any treatment.     

Effect of High Hydrostatic Pressure (HHP) Treatment on Physicochemical Properties of Horse Mackerel (Trachurus trachurus)

The basic objective of this study was to determine the effect of high hydrostatic pressure (HHP; 220, 250 and 330 MPa), holding time (5 and 10 min) and temperature (7, 15 and 25 °C) on some quality parameters of horse mackerel such as colour changes, thiobarbituric acid (TBA-i) and trimethylamine nitrogen (TMA-N), free amino acid content. HHP increased L ^* values of horse mackerel. The a ^* and b ^* of treated horse mackerel did not change significantly after HHP applications. After, HHP, TBA-i and TMA values of all HHP-treated horse mackerel samples remained unchanged than those of untreated samples. The results obtained from this study showed that the quality of high pressure treated horse mackerel is best preserved at 250 MPa, 7–15 °C for 5 min, 220 MPa, 15–25 °C for 5 min, 250 MPa, 15 °C for 10 min and 330 MPa, 25 °C for 10 min.     

Combined effect of high hydrostatic pressure treatment and hydrogen peroxide on Salmonella Enteritidis in liquid whole egg

The effects of high hydrostatic pressure treatment (HHP) of 250, 350, 450 MPa and hydrogen peroxide additions at different concentrations of 0.1, 0.5, 1% in liquid whole egg following high hydrostatic pressure treatment at 250 MPa at 20 °C on Salmonella Enteritidis PT4 in liquid whole egg were investigated. At 20 °C for 5 min treatment, 56.63 and 49.38% injury were determined for the treatment pressures of 250 and 350 MPa, respectively. Injury was not detected and total destruction of Salmonella Enteritidis PT4 was obtained for 5 min treatment at 450 MPa. The obtained results indicated that HHP was a more effective treatment than preheating for the enhancement of the effectiveness of H₂O₂. In order to minimize the adverse effect of HHP on food texture, the HHP treatment of 250 MPa was used throughout this study. Therefore, treating with 0.5% H₂O₂ following 5 min HHP at 250 MPa was determined as an effective way of Salmonella Enteritidis destruction in liquid whole egg. The catalase activity retention was determined as 62.26±0.6% after 3.5 min treatment of LWE at 60 °C. A 5-min treatment at 250 and 450 MPa at 20 °C of LWE resulted in a 78.67±2.1 and 65.01±1.8% retention of catalase activity, respectively.     

Effects of high hydrostatic pressure on physicochemical and functional properties of walnut (Juglans regia L.) protein isolate

BACKGROUND: Walnut (Juglans regia L.) is a good source of protein that has potential application in new product formation and fortification. The main objectives of this study were to investigate the effects of high hydrostatic pressure (HHP) treatment (300–600 MPa 20 min) on physicochemical and functional properties of walnut protein isolate (WPI) using various analytical techniques at room temperature. RESULTS: The results showed significant modification of solubility, free sulfhydryl content and surface hydrophobicity with increased levels of HHP treatment, indicating partial denaturation and aggregation of proteins. Differential scanning calorimetry and fluorescence spectrum analyses demonstrated that HHP treatment resulted in gradual unfolding of protein structure. Emulsifying activity index was significantly (P < 0.05) increased after HHP treatment at 400 MPa, but significantly decreased (P < 0.05) relative to the untreated WPI with further increase in pressure. HHP treatment at 300–600 MPa significantly decreased emulsion stability index. Additionally, HHP‐treated walnut proteins showed better foaming properties and in vitro digestibility. CONCLUSION: These results suggest that HHP treatment could be applied to modify the properties of walnut proteins by appropriate of pressure levels, which will help in using walnut protein as a potential food ingredient. © 2012 Society of Chemical Industry     

Preparation and identification of angiotensin I-converting enzyme inhibitory peptides from sweet potato protein by enzymatic hydrolysis under high hydrostatic pressure

Sweet potato protein hydrolysates (SPPH) with angiotensin I-converting enzyme (ACE) inhibitory activity were prepared by papain, pepsin and alcalase under high hydrostatic pressure (HHP, 100–300 MPa). HHP significantly increased degree of hydrolysis (DH), nitrogen recovery (NR) and molecular weight (MW) <3 kDa fractions contents of SPPH by all three enzymes (P < 0.05). MW < 3 kDa peptide fractions from SPPH by alcalase under 100 MPa showed the highest ACE inhibitory activity (IC₅₀ value 32.24 µg mL⁻¹), and was subjected to purification and identification by semi-preparative RP-HPLC and LC-MS/MS. Fifty-four peptides ranged from 501.28 to 1958.88 Da with 5–18 amino acids were identified and matched sporamin A and B sequences. Five identified peptides with sequences of VSAIW, AIWGA, FVIKP, VVMPSTF and FHDPMLR displayed good ACE inhibitory activity with the contribution of Val, Trp, Phe and Arg. Thus, SPPH by enzymatic hydrolysis under HHP can be potentially used in functional food.     

Beta Vulgaris root as a natural food colouring in doughnut: Dough rheological properties and bioactive composition

In the present study, the influence of Beta vulgaris root powder (BVP) incorporated at 0%, 5%, 7.5%, 10% and 12.5% levels on the empirical and fundamental rheological characteristics; dough texture properties; nutritional and bioactive components in the doughnut were carried out. The addition of BVP, decreased the WAC (58.4%–51.2%), DDT (6.19–1.31 min), extensibility (148–95 mm), and springiness (4.56–3.24 N) and viscosity parameters to varying extent. The frequency sweep test indicated that both the dynamic moduli increased and G' was higher than G" at all levels indicating the solid elastic structure of the dough. The dimensional characteristics of the doughnuts indicated a decrease in volume (103.3–85 mL) and an increase in weight (35.8–46.7 g) and compression force (11.6–14.5 N). The sensory studies indicated that 10% BVP incorporated doughnut was highly acceptable with higher dietary fibre content. The higher retention of betacyanin (17.88 mg 100 g⁻¹), betaxanthin (12.9 mg 100 g⁻¹), betanin (6.61 mg 100 g⁻¹), TPC (25.74 mg GAE 100 g⁻¹), TFC (77.08 mg QE 100 g⁻¹) and TAC (28.76 mMTE 100 g⁻¹) was observed.     

The effect of high hydrostatic pressure on the microbiological, chemical and sensory quality of fresh gilthead sea bream (Sparus aurata)

The effect of different temperature/time/pressure high hydrostatic pressure (HHP) treatment on quality and shelf life of sea bream were studied. Different high-pressure treatments (at 3, 7, 15 and 25 °C, 5–10 min and 220, 250 and 330 MPa) were tested to establish the best processing conditions for quality of sea bream. The effect of the process on the quality of the sample was examined by colour, trimethylamine nitrogen and thiobarbituric acid number analysis. Based on the results of the parameter, the best combinations of HHP treatments were determined as 3 °C/5 min/250 MPa–15 °C/5 min/250 MPa for sea bream. The effects of this combination treatment on sensory, chemical and microbiological properties of sea bream stored at 4 °C were studied. The results obtained from this study showed that the shelf life of untreated and HHP treated stored in refrigerator, as determined by overall acceptability of sensory and microbiological data, is 15 days for untreated sea bream and 18 days for treated sea bream at 3 °C/5 min/250 MPa and at 15 °C/5 min/250 MPa treated sea bream.     

Chemical Forces,Structure, and Gelation Properties of Sweet Potato Protein as Affected by pH and High Hydrostatic Pressure

Sweet potato is one of cheap sources for starch industries worldwide, and exploiting starch wastewater as an alternative protein source is mainly environmental and economic concerns. In this study, the effects of high hydrostatic pressure (HHP; 250, 400, and 550 MPa) on chemical forces, structure, and gelation properties of sweet potato protein (SPP) at pH 3.0, 6.0, and 9.0 were investigated. The values of surface hydrophobicity (H_o) and absolute value of zeta potential of SPP significantly increased from 250 to 550 MPa (p?<?0.05) at all three pH conditions. The total amount of sulfhydryl (-SH-) groups in SPP decreased after HHP at pH 9.0, whereas the amount of free -SH- increased. High molecular mass aggregates (>?180 kDa) were observed in SPP after HHP at pH 6.0 and 9.0 by SDS-PAGE. Regarding elastic rheological behaviors, storage modulus (G′) values of SPP were significantly strengthened after HHP treatment. In addition, textural properties and water-holding capacity of gels made from SPP after 250 and 400 MPa at pH 9.0 were significantly improved, and the gels showed a compact and uniform gel network with the contribution of immobilized water fractions. The gel properties exhibited by SPP after HHP treatment at different pH levels, in particular after 400 MPa at pH 9.0, suggested that it could be potential protein resources as new gelling reagent in the food system.     

Microbial and Sensory Effects of Combined High Hydrostatic Pressure and Dense Phase Carbon Dioxide Process on Feijoa Puree

High hydrostatic pressure (HHP) is used for microbial inactivation in foods. Addition of carbon dioxide (CO₂) to HHP can improve microbial and enzyme inactivation. This study investigated microbial effects of combined HHP and CO₂ on Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae, and evaluated sensory attributes of treated feijoa fruit puree (pH 3.2). Microorganisms in their growth media and feijoa puree were treated with HHP alone (HHP), or saturated with CO₂ at 1 atm (HHPcarb), or 0.4%w/w of CO₂ was injected into the package (HHPcarb+CO₂). Microbial samples were processed at 200 to 400 MPa, 25 °C, 2 to 6 min. Feijoa samples were processed at 600 MPa, 20 °C, 5 min, then served with and without added sucrose (10%w/w). Treated samples were analyzed for microbial viability and sensory evaluation. Addition of CO₂ enhanced microbial inactivation of HHP from 1.7‐log to 4.3‐log reduction in E. coli at 400 MPa, 4 min, and reduction of >6.5 logs in B. subtilis (vegetative cells) starting at 200 MPa, 2 min. For yeast, HHPcarb+CO₂ increased the inactivation of HHP from 4.7‐log to 6.2‐log reduction at 250 MPa, 4 min. The synergistic effect of CO₂ with HHP increased with increasing time and pressure. HHPcarb+CO₂ treatment did not alter the appearance and color, while affecting the texture and flavor of unsweetened feijoa samples. There were no differences in sensory attributes and preferences between HHPcarb+CO₂ and fresh sweetened products. Addition of CO₂ in HHP treatment can reduce process pressure and time, and better preserve product quality.     

USE of HYDROSTATIC PRESSIJRE to PRODUCE HIGH QUALITY and SAFE FRESH PORK SAUSAGE

The effects of high hydrostatic pressure (HHP) on the survival of microor ganisms and quality changes of fresh pork sausages were investigated. Pork sausage inoculated with Listeria monocytogenes at 1O⁷ CFU/gram was prepared and subjected to HHP at 414 and 552 MPa, at treatment temperatures of 25 and SOC. for various time intervals to examine pressure effects on inactivation of bacteria. At a pressure of 414 MPa and SOC for 2 min, the microorganisms in fresh pork sausages were completely inactivated. Partial discoloration of meat was observed after 10 min of pressurization above 414 MPa at either temperature.
The effect of HHP treatment on the physical and rheological properties of sausage was also studied. the sausages increased infirinness with an increase in the pressure applied. the pressure-treated sausages were generally lighter in color as compared with the heat-treated sausages.
The optimal pressure/temperature/time conditions that resulted in minimum quality changes with microbiologically safe fresh pork sausages was 414 MPa and SOC for 2 min.     

High hydrostatic pressure treatment and storage of carrot and tomato juices: Antioxidant activity and microbial safety

The application of high hydrostatic pressure (HHP) (250 MPa, 35 °C for 15 min) and thermal treatment (80 °C for 1 min) reduced the microbial load of carrot and tomato juices to undetectable levels. Different combinations of HHP did not cause a significant change in the ascorbic acid content of either juice (P > 0.05). Both heat treatments (60 °C for 5–15 min and 80 °C for 1 min) resulted in a significant loss (P < 0.05) in the free‐radical scavenging activity as compared to untreated samples. HHP‐treated juices showed a small loss of antioxidants (below 10%) during storage. The ascorbic acid content of pressurized tomato and carrot juices remained over 70 and 45% after 30 days of storage, respectively. However, heat treatment caused a rapid decrease to 16–20%. Colour changes were minor (ΔE = 10) for pressurised juices but for heat‐pasteurised samples it was more intense and higher as a result of insufficient antioxidant activity. HHP treatment (250 MPa, 35 °C for 15 min) led to a better product with regard to anti‐radical scavenging capacity, ascorbic acid content and sensory properties (colour, pH) of the tomato and carrot juices compared to conventional pasteurisation. Therefore, HHP can be recommended not only for industrial production but also for safe storage of fresh juices, such as tomato and carrot, even at elevated storage temperatures (25 °C). Copyright © 2007 Society of Chemical Industry     

The effects of high hydrostatic pressure at subzero temperature on the quality of ready-to-eat cured beef carpaccio

We compared the application of high hydrostatic pressure (HHP) on unfrozen carpaccio (HHP at 20°C) and on previously-frozen carpaccio (HHP at -30°C). HHP at 20°C changed the color. The pressure increase from 400 to 650MPa and the time increment from 1 to 5min at 400MPa increased L* and b*. a* decreased only with 650MPa for 5min at 20°C. The prior freezing of the carpaccio and the HHP at -30°C minimized the effect of the HHP on the color and did not change the shear force, but increased expressible moisture as compared to the untreated carpaccio. HHP at 20°C was more effective in reducing the counts of microorganisms (aerobic total count at 30°C, Enterobacteriaceae, psychrotrophs viable at 6.5°C and lactic acid bacteria) than HHP at -30o C. With HHP at 20°C, we observed a significant effect of pressure and time on the reduction of the counts.     

Inactivation of Escherichia coli and Listeria innocua in kiwifruit and pineapple juices by high hydrostatic pressure

Escherichia coli and Listeria innocua in kiwifruit and pineapple juices were exposed to high hydrostatic pressure (HHP) at 300 MPa for 5 min. Both bacteria showed equal resistance to HHP. Using low (0 degrees C) or sub-zero (-10 degrees C) temperatures instead of room temperature (20 degrees C) during pressurization did not change the effectiveness of HHP treatment on both bacteria in studied juices. Pulse pressure treatment (multiple pulses for a total holding time of 5 min at 300 MPa) instead of continuous (single pulse) treatment had no significant (p>0.05) effect on the microbial inactivation in kiwifruit juice; however, in pineapple juice pulse treatment, especially after 5 pulses, increased the inactivation significantly (p<0.05) for both bacteria. Following storage of pressure-treated (350 MPa, 20 degrees C for 60 s x 5 pulses) juices at 4, 20 and 37 degrees C up to 3 weeks, the level of microbial inactivation further increased and no injury recovery of the bacteria were detected. This work has shown that HHP treatment can be used to inactivate E. coli and L. innocua in kiwifruit and pineapple juices at lower pressure values at room temperature than the conditions used in commercial applications (>400 MPa). However, storage period and temperature should carefully be optimized to increase the safety of HHP treated fruit juices.     

Effects of high hydrostatic pressure on enzymes, phenolic compounds, anthocyanins, polymeric color and color of strawberry pulps

BACKGROUND: Changes in activity of polyphenol oxidase (PPO), peroxidase (POD) and β‐glucosidase, individual phenolic compounds other than anthocyanins, total phenols, monomeric anthocyanins, polymeric color and instrumental color of strawberry pulps were assessed after high hydrostatic pressure (HHP) (400–600 MPa 5–25 min^?1) at room temperature. RESULTS: β‐Glucosidase was activated by 4.7–16.6% at 400 MPa 5–25 min^?1 and inactivated by 8.0–41.4% at 500 or 600 MPa. PPO and POD were inactivated at all pressures, the largest reduction in activity being 41.4%, 51.5% and 74.6%, respectively. The individual phenolic compounds and total phenols decreased at 400 MPa, but total phenols increased at 500 or 600 MPa. However, the monomeric anthocyanins, polymeric color and redness (a*) exhibited no change. HHP induced a decrease in lightness (L*) and an increase in yellowness (b*) at 400 MPa, but no significant alteration in L* value and b* value at 500 or 600 MPa was observed; this was attributed to higher residual activity of PPO, POD and β‐glucosidase at 400 MPa. Total color difference (ΔE) was ≥ 5 at 400 MPa and ?3 at 500 or 600 MPa. CONCLUSION: HHP effectively retained anthocyanins, phenolic compounds and color of strawberry pulps, and partly inactivated enzymes. Copyright © 2011 Society of Chemical Industry     

Inactivation of Vibrio parahaemolyticus in Hard Clams (Mercanaria mercanaria) by High Hydrostatic Pressure (HHP) and the Effect of HHP on the Physical Characteristics of Hard Clam Meat

Shellfish may internalize dangerous pathogens during filter feeding. Traditional methods of depuration have been found ineffective against certain pathogens. The objective was to explore high hydrostatic pressure (HHP) as an alternative to the traditional depuration process. The effect of HHP on the survival of Vibrio parahaemolyticus in live clams (Mercanaria mercanaria) and the impact of HHP on physical characteristics of clam meat were investigated. Clams were inoculated with up to 7 log CFU/g of a cocktail of V. parahaemolyticus strains via filter feeding. Clams were processed at pressures ranging from 250 to 552 MPa for hold times ranging between 2 and 6 min. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level (<10¹ CFU/g), achieving >5 log reductions. The volume of clam meat (processed in shell) increased with negligible change in mass after exposure to pressure at 552 MPa for 3 min, while the drip loss was reduced. Clams processed at 552 MPa were softer compared to those processed at 276 MPa. However, all HHP processed clams were found to be harder compared to unprocessed. The lightness (L*) of the meat increased although the redness (a*) decreased with increasing pressure. Although high pressure‐processed clams may pose a significantly lower risk from V. parahaemolyticus, the effect of the accompanied physical changes on the consumer's decision to purchase HHP clams remains to be determined. Practical Application : Shellfish may contain dangerous foodborne pathogens. Traditional methods of removing those pathogen have been found ineffective against certain pathogens. The objective of this research was to determine the effect of high hydrostatic pressure on V. parahaemolyticus in clams. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level, achieving >5 log reductions.     

Effect of high pressure processing in the quality of sea bass (Dicentrarchus labrax) fillets: Pressurization rate,pressure level and holding time

High pressure processing (HPP) is a technology able to reduce microorganisms and to modify food functional properties. This study aims to investigate the effect of three pressure variables (pressure levels of 100–400 MPa, pressure holding time of 0–30 min, and pressurization rate of 8 and 14 MPa s^− 1) in microbiological and physical analyses, and in myofibrillar proteins profiles in sea bass fillets.Pressurization rate induced changes in all parameters evaluated, although in a lesser extent than other variables. In general, the characteristics of fillets treated at 100 MPa were not different from non-treated samples. The magnitude of changes increased with pressure level (250–400 MPa) and holding time (0–30 min). In general, with the increase of pressure level and holding time, fillets become whitish, microbiological load and water holding capacity decreased, pH increased, and myofibrillar proteins with molecular weights below 30 kDa increased, whereas those with lower isolectric point values decreased.HPP can be a potential tool to process fillets due to the improvement in microbiological safety (about 2 log CFU g^− 1 reduction in the treatment at 400 MPa–30 min), which might result in an extended shelf life.Industrial relevanceHigh pressure processing is an interesting technology for food preservation due to its ability to reduce microorganisms and to modify food functional properties. This study brought new evidences about the effect of high pressure processing on sea bass fillets, namely in myofibrillar protein profiles (SDS-PAGE and IEF electrophoreses). Variables such as pressure holding time and pressurization rate, besides pressure level, are also important in the choice of high pressure processing conditions. The results also suggest that high pressure processing might delay the degradation of fish muscle. The advantages of products treated with high pressure processing can lead to new opportunities in the market, being important for the food industry.     

Extract of Salicornia europaea in fresh pasta to enhance phenolic compounds and antioxidant activity

Extract from Salicornia europaea was added to durum wheat fresh pasta. Sensory properties, cooking quality, microbiological stability, content in bioactive compounds and antioxidant activity, before and after pasta digestion were studied. The extract was obtained by ultrasound-assisted extraction. From the technological point of view the extract did not affect pasta dough and the cooking parameters and sensory properties of the enriched samples were found similar to the control pasta. No antimicrobial effect was exerted by the extract. From the chemical point of view interesting findings were recorded for pasta before and after digestion. Specifically, data of bioaccessible fraction of digested sample showed a significantly higher amount of total phenols and flavonoid content (11.52 mg gallic acid g⁻¹ and 0.55 mg quercetin g⁻¹ respectively) than digested control pasta (9.54 mg gallic acid g⁻¹ and 0.23 mg quercetin g⁻¹ respectively). The antioxidant activity of enriched sample also increased compared to the control pasta (6.20 vs. 2.50 μmoles FeSO₄ g⁻¹).     

超高压处理对养殖大黄鱼保鲜效果的影响

研究超高压处理对养殖大黄鱼保鲜效果的影响,经不同超高压（100、200、300、400、500 MPa,保压时间10、15 min）处理后,研究其pH值、aw、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、硫代巴比妥酸（thiobarbituric acid,TBA）值、三甲胺（trimethylamine,TMA）值、菌落总数的变化。其次,研究大黄鱼在4 ℃冷藏期间pH值、aw、TVB-N值、TBA值、TMA值、菌落总数的变化情况。结果表明,超高压处理后大黄鱼的pH值随着压力的升高而增加;aw随压力的升高而减小;TVB-N值随着压力的增加呈减小的趋势;TBA值随着压力的上升而增大;TMA值略有上升但幅度不大;菌落总数随压力增加明显降低。实验组的大黄鱼pH值和aw在4 ℃贮藏期先升后降;500 MPa、15 min 处理后45 d,大黄鱼的TVB-N值和TMA值增加,含量分别不超过35 mg/100 g和5 mg/100 g,TVB-N值和TMA值得到了有效控制;第45天500 MPa、15 min处理组大黄鱼的菌落总数为5.7×104 CFU/mL。因此,压强500 MPa保压时间15 min为养殖大黄鱼最适合的保鲜条件。