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1.
The effect of the potentially probiotic bacteria strain of Lactobacillus acidophilus Bauer and probiotic bacteria Bifidobacterium animalis ssp. lactis BB12 on proteolytic changes of proteins in dry-cured loins during fermentation and cold storage was studied. Results of the conducted tests demonstrated that the use of probiotic bacteria for the production of dry-cured meats impacts the generation of products of protein proteolysis with high antioxidant activity. The highest antioxidant activity of peptides after fermentation and cold storage was observed in the loin with the strain B. animalis ssp. lactis BB12 and the loin with the mixture of strains L. acidophilus Bauer and B. animalis ssp. lactis BB12. Qualitative analysis of peptides demonstrated that peptides with weight below 3.5 kDa are characterized by the highest capacity of quenching the ABTS cation radical, including the peptides in loins with the strain B. animalis ssp. lactis BB12.  相似文献   

2.
In this study, skim milk was fermented using 14 Lactobacillus strains for 16 h at 42 °C or for 48 h at 25 °C. On conclusion of fermentation, the proteolytic, angiotensin converting enzyme-inhibitory (ACE-I), and antioxidant activities as well as the inhibition of thrombin and cholesterol micellar solubility were determined. The results revealed that Lb. paracasei B-4564 exhibited the highest ACE-I activity (68.11%) under the 42 °C for 16 h condition, while Lb. rhamnosus B-1445 demonstrated the highest ACE-I activity (92.23%) under the 25 °C for 48 h condition. Lb. paracasei B-4564 exhibited the highest inhibition rate of thrombin (42.43 and 48.10%) and cholesterol (68.60 and 87.01%) under the 42 °C for 16 h and 25 °C for 48 h conditions, receptively. Lb. rhamnosus B-442 exhibited the highest DPPH radical scavenging activity of 95.63 and 62.89% under the 42 °C for 16 h and 25 °C for 48 h conditions, receptively. Lb. rhamnosus B-1445 demonstrated the highest Fe2+ chelating activity and reducing power under both the tested fermentation conditions.  相似文献   

3.
Short-chain fatty acids (SCFAs) acetate, propionate, butyrate and lactate were determined in 12 % reconstituted skim milk (RSM) and RSM supplemented with inulin (RSMI). The fermentation was performed with Bifidobacterium animalis subsp. lactis (BB 12) and Lactobacillus rhamnosus LGG ATCC 53013. Fermentation culture activities produced substantial amounts of SCFAs, which were detected and quantitated using a HPLC-UV technique. Using HPLC-UV, we were able to detect low concentrations of lactate and SCFAs from fermented samples; lactate, acetate, propionate and butyrate were detected at 10.10, 12.06, 14.80 and 18.06 μg/mL, respectively. The retention time of all SCFAs and lactic acid were similar to the standard quality control (±0.05), and average recovery ranged between 89.73 and 91.03 %. The experimental conditions and sample preparation were applied to preparative HPLC to isolate and purify SCFAs with concentration range between 0.09 and 2.86 mg/mL. The purity of extracted SCFAs was confirmed using atmospheric pressure chemical ionization/mass spectrometry by determining the molecular masses of target purified compounds. The scaled up validated analytical HPLC-UV method will further enhance and improve the use of this approach to produce purified large-scale SCFAs.  相似文献   

4.
The combined effect of high pressure processing and temperature on aminopeptidases activity of lactic acid bacteria used as starter cultures in brined cheese manufacturing, in order to find the optimum process conditions for acceleration of the significant long-duration cheese ripening step, was investigated.The effect of high hydrostatic pressure (HP) (100–450 MPa) combined with temperature (20–40 °C) on the activity of five aminopeptidases (PepN, PepX, PepY, PepC, and PepA) of Streptococcus thermophilus ACA-DC 0022 and Lactococcus lactis ACA-DC 0049, used as the starter culture for white Greek brine cheese (feta) production, was studied. S. thermophilus aminopeptidases PepN, PepX, PepA, and PepC were activated at pressures up to 200 MPa, and all studied temperatures (20–40 °C), while for L. lactis, PepN, X, and Y were activated at pressures up to 300 MPa and temperatures up to 30 °C and PepA at the same temperature range but milder pressures (up to 200 MPa). For L. lactis, PepC an increase in activity was observed at all studied pressures but only at 20 °C. A multi-parameter equation was used for predicting the activation of all aminopeptidases in the pressure and temperature domain. Overall, processing at 200 MPa and 20 °C may be selected as the optimum conditions for maximum activation of all aminopeptidases of both S. thermophilus ACA-DC 0022 and L. lactis ACA-DC 0049. A 20-min treatment at these conditions leads to an average threefold increase in activity which could lead to better and faster maturation of white cheese.  相似文献   

5.
The use of probiotic microorganisms has been limited by the difficulty of maintaining their viability during processing and throughout the product’s shelf life. This study evaluated the viability of microencapsulating Lactobacillus acidophilus (LA) and Bifidobacterium animalis subsp. lactis (BL) using the spray chilling technique to add them to savory cereal bars. The results showed that spray chilling generated a powder that was composed of smooth and continuous spheres with low moisture content and low water activity. The microencapsulated microorganisms exhibited a storage viability at least of 90 days as microparticles and in savory cereal bars, and their counts were superior to those resulting from other methods of adding activated and lyophilized probiotics to savory cereal bars. Thus, microparticles prepared by spray chilling are good vehicles for incorporating probiotics into cereal bars and have the potential to release the probiotics in the consumers’ intestines by means of fat digestion. Savory cereal bars that did and did not contain probiotics exhibited no differences in sensorial acceptance or commercial potential.  相似文献   

6.
The aim of the present study was to evaluate an agar medium for the quantitative analysis of bifidobacteria in probiotic milk products on the market, and to investigate the identities of active strains. For this purpose, three sour milk products and a soft cheese brand were each analysed ten times with Wilkins-Chalgren agar (WCA) supplemented with mupirocin, and with MRS agar supplemented with dicloxacillin at two different concentrations. By statistical analysis of the bacterial counts obtained, WCA was shown to have the best detection rate. All the sour milk products examined conformed to Swiss food legislation and contained more than 106 cfu of bifidobacteria per gram of living bifidobacteria. All the samples of soft cheese analysed revealed counts that were clearly (approximately 2 logs) below this minimum requirement. Isolated bifidobacteria strains were all identical with reference strains from producer companies shown by pulsed-field gel electrophoresis (PFGE) profiling. According to the labels, the three brands of sour milk examined contained different strains of bifidobacteria (Bifidobacterium lactis Bb 12, Bifidobacterium animalis DN 173010 and Bifidobacterium species 420). However, all the strains revealed repeatedly identical PFGE-patterns, thus showing a close relationship. These findings show that a better taxonomical definition of commercially used bifidobacteria strains is needed.  相似文献   

7.
The use of cheese whey and probiotic cultures in the production of dairy beverages has been highly attractive; nonetheless, whey-based goat beverages tend to be poor and watery when compared to fermented milks. The addition of fruits and fibre ingredients might improve texture and mouthfeel of this kind of product. Fermented whey-based goat beverages prepared using Streptococcus thermophilus TA-40 as starter culture, with added guava or soursop pulps, and with or without addition of partially hydrolysed galactomannan from Caesalpinia pulcherrima seeds (PHGM), showed to be good vehicles for Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus Lr-32, maintaining their viability above 7 log CFU/ml during 21 days. PHGM increased the dietary fibre content and enhanced the instrumental texture and sensory features of both guava and soursop dairy beverages, especially texture, appearance, and overall acceptability. The PHGM might be recommended to improve nutritional and sensory quality of fermented probiotic beverages produced with goat milk and cheese whey.  相似文献   

8.
K.E. Almeida  M.N. Oliveira 《LWT》2008,41(2):311-316
The acidification rates of Lactobacillus delbrueckii subsp. bulgaricus (Lb), Lactobacillus acidophilus (La), Lactobacillus rhamnosus (Lr), and Bifidobacterium animalis subsp. lactis (Bl) in co-culture with Streptococcus thermophilus (St) were studied in Minas frescal cheese whey. Effects of the co-culture composition and the final pH values on the kinetic parameters of acidification, post-acidification and counts of health promoting micro-organisms were also studied. Fermentation time to reach pH 4.5 was longer when St-Lr co-culture was used, while St-Lb had the shortest fermentation time when compared with the other co-culture combinations. All products showed development of acidity during the storage period and lowest values had been observed employing St-Bl co-culture. The technological interest of using M. frescal cheese whey for the production of a probiotic lactic beverage is discussed in this article.  相似文献   

9.
This study was designed to isolate lactic acid bacteria (LAB) with β-glucosidase activity and probiotic properties from Korean fermented foods. Among nine isolates, four LAB strains had excellent survival rates at pH 2.5 with 0.3% (w/v) pepsin for 3 h and 0.3% (w/v) oxgall for 24 h. Four LAB strains did not produce β-glucuronidase and showed adhesion ability to HT-29 cells that was superior to that shown by the reference strain Lactobacillus rhamnosus GG. All four strains were sensitive to ampicillin, tetracycline, chloramphenicol, and doxycycline. These strains were identified as Leuconostoc mesenteroides H40, Lactobacillus plantarum FI10604, L. brevis FI10700, and L. perolens FI10842 by 16S rRNA gene sequence, respectively. It was found that L. perolens FI10842 produced the highest β-glucosidase activity (49.10 mU/mL). These results indicate that the four LAB strains could be used as potential probiotic. Especially L. perolens FI10842 could be used as a starter culture for fermentation.  相似文献   

10.
In this study, a gliding arc discharge (GAD) microplasma system was designed, and its decontamination effect was investigated on stainless steel (SS), silicone (Si), and polyethylene terephthalate (PET) surfaces artificially contaminated with 8.15 ± 0.28 log cfu/mL of Escherichia coli and 6.18 ± 0.21 log cfu/mL of Staphylococcus epidermidis. Each of the contaminated surfaces was treated with high purity air (79% nitrogen and 21% oxygen) or nitrogen plasmas for 1–10 min at varying rates of gas flow. Significant reductions of 3.76 ± 0.28, 3.19 ± 0.31, and 2.95 ± 0.94 log cfu/mL in S. epidermidis, and 2.72 ± 0.82, 4.43 ± 0.14, and 3.18 ± 0.96 log cfu/mL in E. coli on SS, Si, and PET surfaces, respectively, were achieved after 5 min of plasma treatment by using nitrogen as the plasma forming gas (p < 0.05). The temperature changes of each surface during plasma generation were lower than 35 °C and were not affected by the type of plasma forming gas. Additionally, morphological changes in the structure of E. coli and S. epidermidis after GAD plasma treatments were demonstrated using scanning electron microscopy (SEM).  相似文献   

11.
The aim of our study was to conduct a selection of the monocultures capable of providing the most attractive sensory features of the final product. Four fermented goat's milk beverages were produced with probiotic monocultures containing Lactobacillus (Lb. acidophilus La‐5, Lb. rhamnosus K3 and Lb. plantarum O20) and Bifidobacterium (Bif. animalis subsp. lactisBB‐12). A sensory analysis and microbiological assessment of fermented goat's milk beverages were made at the beginning of the study and after 3, 7, 10 and 14 days of refrigerated storage (5 ± 1 °C). We found that samples including monocultures Lb. plantarum O20 and Bif. animalis subsp. lactisBB‐12 were differentiated from other goat's milk beverages.  相似文献   

12.
The aim of this study was to use the process of osmotic dehydration to enrich banana slices with Lactobacillus rhamnosus encapsulated in a double emulsion. The effect of a pulsed vacuum and the concentration of the osmotic solution on the impregnation of the microorganism and on mass transfer during osmotic dehydration of the fruit were assessed. The kinetics of the water loss (WL), solid gain (SG) and water activity (aw) were obtained using an aqueous solution with 40, 50 and 60% sucrose with emulsion and a vacuum pulse of 50 mbar for 10 and 20 min at the beginning of the osmotic process. The high concentrations of sucrose in the osmotic solution, combined with the application of a pulsed vacuum, produced an increase in the rates of WL and SG of the osmodehydrated banana, as well as a reduction of its aw. L. rhamnosus survived at levels above 107 CFU/g in the hypertonic solution and in the osmodehydrated bananas. Scanning electron microscopy (SEM) showed that the encapsulated probiotic adheres to the banana’s surface, which demonstrates that double emulsions can be used to impregnate probiotics in vegetal tissues.  相似文献   

13.
The objective of this study was to investigate the combined effect of thermosonication (TS) and pulsed electric fields (PEF) against Saccharomyces cerevisiae in Chinese rice wine. The effectiveness of standalone TS treatment (35 °C, 750  W, 120 min) on the inactivation of S. cerevisiae was insignificant (0.76 log CFU/mL). However, 2.88 log CFU/mL of S. cerevisiae were inactivated when the standalone PEF treatment with moderate conditions (35 °C, 12 kV/cm, 120 μs) was applied. The combination of TS and PEF had an additive effect on the inactivation of S. cerevisiae, and the sequence applied (TS-PEF or PEF-TS) markedly influenced the inactivation results (P < 0.05). In particular, the microbial inactivation by TS-PEF (3.72 log CFU/mL) was higher than that by PEF-TS (3.48 log CFU/mL); this result indicates that PEF were able to restrain the effect of TS. On the other hand, TEM micrographs of S. cerevisiae after the different treatments showed that the combined techniques resulted in more severe disruptions on cells. Higher cytoplasmic shrinkage and more intracellular material leakage were observed from the TEM observations of the cells treated by TS-PEF. These results may serve as a reference of the potential application of the combined treatment TS-PEF for microbial inactivation in Chinese rice wine.  相似文献   

14.
The inactivation and photoreactivation response of six seafood-isolated Listeria monocytogenes and one Listeria innocua strain after pulsed light (PL) treatment was evaluated. The lower inactivation levels found after exposure of treated samples to daylight during the first 90 min of storage confirmed that both L. innocua and L. monocytogenes have the capability to photorepair PL-induced DNA damage upon appropriate conditions. Photoreactivation levels from 0.2 to 2.1 log CFU cm?2 were observed depending on treatment intensity (fluence) and Listeria strain. Complete photorepair of PL-caused damage was not found even after treatments inducing low inactivation levels. Photoreactivation increased up to 2.1 log with the applied fluence up to a threshold able to cause between 2.4 and 5.4 log reductions under dark storage. Photorepair was not avoided but lower photoreactivation was observed after higher fluence inducing more than 6 log reductions under dark storage. Both L. innocua and L. monocytogenes serotype 1/2b exhibited the highest photoreactivation levels whereas serotypes 1/2a showed the lowest ones. The overall inactivation and photoreactivation responses of tested Listeria strains were comparable indicating that L. innocua may be a good surrogate for the safe evaluation, optimization and validation of PL technology to control L. monocytogenes in food products and food processing facilities.  相似文献   

15.
Microwave drying is usually combined with vacuum environment in conjunction with hot air flow to draw the moisture rapidly. The moisture content of the vegetables undergoing drying is hard to measure online. This research designed a microwave vacuum drying (MVD)-low-field nuclear magnetic resonance (NMR) smart device and investigated the feasibility of NMR method for online measurement of state of moisture during MVD. The relation between the signal amplitude (A 2) and the true moisture content (M 1) of six kinds of vegetables (mushroom, carrot, potato, lotus, edamame, vegetable corn) was fitted to estimate if NMR can measure the M 1 of vegetables directly. Results showed that A 2 and M 1 of different fresh vegetables had no single empirical mathematical model to fit. However, for each kind of these vegetables, the A 2 and corresponding M 1 in different MVD stages showed a significant linear relationship. The predicted moisture content (M 2) of mushroom: M 2 = 5.25351 × 10?4 A 2 ? 0.34042, R = 0.996; carrot: M 2 = 5.78756 × 10?4 A 2 ? 0.14108, R = 0.998; potato: M 2 = 3.10019 × 10?4 A 2 ? 0.10612, R = 0.991; lotus: M 2 = 2.32415 × 10?4 A 2 ? 0.01573, R = 0.998; edamame: M 2 = 3.13310 × 10?4 A 2 ? 0.4198, R = 0.996; vegetable corn: M 2 = 1.69461 × 10?4 A 2 ? 0.09063, R = 0.995. The linear models between M 2 and A 2 were able to estimate the end point (M 1 < 8%) of MVD with a high accuracy (P > 0.950).  相似文献   

16.
The aim of this study was to evaluate the influence of edible coatings based on linseed mucilage, alginate, and fructooligosaccharide containing Lactobacillus casei LC-01 on the shelf-life of fresh-cut yacon cubes. The cell viability and survival under in vitro gastrointestinal conditions analysis were performed to evaluate the stability of the microorganism. To evaluate the influence of edible coatings on fresh-cut yacon, physicochemical parameters pH, acidity, soluble solids, color, and weight loss were analyzed. Edible coatings were efficient probiotic cells carrier, preserving the number of viable cells at about 8 log CFU g?1. Under simulated gastrointestinal conditions, the reduction in the number of viable cells of the microorganism was on average 2.96 log CFU g?1, indicating the yacon as viable matrix to carrier probiotic bacteria. The edible coatings helped to preserve the physicochemical parameters of the vegetable, reducing the weight loss and darkening, important factors for the commercialization of the product.  相似文献   

17.
In this study, orange, tomato, apple juices, and sour cherry nectar were exposed to an atmospheric pressure plasma jet. Plasma treatments were carried out using air as a precursor under constant gas flow (3000 L/h) at 650 W for different treatment times (30, 60, 90, and 120 s). After plasma processing, reduction of Escherichia coli, Hunter’s color parameters (L*, a*, b*), total phenolic content, and pH values were evaluated. The inactivation effect of cold atmospheric plasma (CAP) was investigated on E. coli, and the highest significant reductions were achieved in apple juice (4.02 ± 0.03 log CFU/mL) followed by sour cherry (3.34 ± 0.09 log CFU/mL), while the values in orange (1.59 ± 0.17 log CFU/mL) and tomato juices (1.43 ± 0.22 log CFU/mL) were lower, which could be attributed to the food matrix. Color parameters, except for apple juice, did not show significant changes after processing. Compared to untreated juice, plasma treatment yielded higher phenolic content from 10 to 15%, while pH values did not change significantly and the temperature remained below 40 °C after all plasma treatments. This study showed that CAP treatment had positive influences on phenolic stability and color change in all samples regardless of food intrinsic factors, while it was more effective on bacterial inactivation in clear juices than turbid ones. Our results indicate that atmospheric plasma appears to be a promising technology for microbial inactivation without causing undesirable changes in food product.  相似文献   

18.
A modified diffusion-based mathematical model is proposed to describe the moisture movement during continuous and intermittent drying of Eucalyptus saligna. This model includes the temperature change, the surface drying coefficient (β n ) and 2 diffusion coefficients [from green to FSP (D f ) and from FSP to dry condition (D o )] as important parameters. The final model expression obtained was M?=?exp (??25 β n 2 D t /l2) with the β n used was 1.5807 kg m?2 s?1, the D f was 2.26?×?10?11 m2 s?1, and the D o was 5.85?×?10?12 m2 s?1. The range of temperature change between heating and non-heating phases in the intermittent drying regimes was from 24.9 to 31.8 °C. The R2 values obtained when the model was fitted into the drying data of different intermittent regimes ranged from 71.5 to 85.9%. The R2 value was 87.4% when the model was fitted into continuous trial data. The high values of R2 indicate that the model can be used to understand the moisture reduction both in intermittent and continuous regimes.  相似文献   

19.
Potatoes are an important food in many regions of the world and are commonly used in a variety of food products. Thermal transition and thermo-physical properties of potatoes are important in order to design efficient food processes and select appropriate storage conditions. In this study, we determined the thermal transitions and thermophysical properties of raw and blanched/par-fried potato for a temperature range of ??32 to 21.1 °C. Using differential scanning calorimetry, we found an initial freezing point (Tf) at ??1.8?±?0.1 °C, an onset of melting (Tm) at ??9.9?±?0.2 °C and an unfreezable water content (Xw) for maximally freeze-concentrated raw potato at 0.21 kg water/kg potato. Corresponding values for blanched/par-fried potatoes were ??0.9?±?0.1 °C, ??11.0?±?0.2 °C and 0.18 kg water/kg potato. Results show that an increase in solids content decreased Tf of both raw and blanched potatoes. We modelled the relationship between them using the Chen model. The apparent specific heat (Capp) increased around Tf to 31.7?±?1.13 kJ/kg K for raw potato and 26.7?±?0.62 kJ/kg K for blanched/par-fried potato. For frozen raw potato at ??32 °C, thermal diffusivity (α) was 0.89?±?0.01?×?10??6 m2/s and thermal conductivity (k), 1.82?±?0.14 W/m K, respectively. These values were higher for frozen raw potato than for the unfrozen raw potato (0.15?±?0.01?×?10??6 m2/s and 0.56?±?0.08 W/m K, respectively at 21.1 °C). The apparent density (ρ) of frozen raw potato (992?±?4.00 kg/m3 at ??32 °C) was less than that for unfrozen raw potato (1053?±?4.00 kg/m3 at 21.1 °C), and a similar trend was obtained for blanched/par-fried potato (993?±?2.00 kg/m3 at ??32 °C and 1188?±?7.00 kg/m3 at 21.1 °C, respectively). This study established a correlation between thermo-physical properties and temperature. Findings may be used to inform the design and optimization of freezing processes and frozen storage for potato products.  相似文献   

20.
The water vapor permeance (WVP; g m?2 d?1 Pa?1) of packaging films quantifying the water vapor transfer rate between foods and its surroundings is usually determined in units operating under steady-state conditions that do not necessarily reflect food handling scenarios. This study evaluated the determination of the WVP of a polyethylene (PE) film by steady-state method ASTM F1249-06 using a permeability cell and unsteady-state method ASTM E96/E96M in which 102 vacuum-sealed PE bags containing silica gel were stored (37.8 °C, 75% relative humidity) and weighed over 25 days. Average steady-state WVP (2.935 ± 0.365 × 10?3, n = 4) fell within the 95% quantiles of unsteady-state WVP values (1.818–3.183 × 10?3, n = 2142). Moisture uptake of dehydrated mango stored at 37.8 °C and 75% relative humidity was predicted with WVP values obtained by both methods. Predictions were validated by monitoring over 25 days the weight gain of 100 PE bags with dry mango. Experimental moisture averages during storage fell within one standard deviation of predictions using the unsteady-state WVP (R 2 = 0.974). The same was observed only until day 15 for predictions obtained with the steady-state WVP. Calculations for days 20–25 overestimated the moisture uptake by 6.0–7.2%, resulting in registered R 2 = 0.924. The unsteady-state WVP determination is low-cost, uses large numbers of film samples, and allowed more accurate predictions of dry mango moisture uptake. Knowledge of the moisture uptake controlled by the film WVP is essential when predicting the safety and quality changes limiting the shelf-life of foods.  相似文献   

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