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1.
In this research, the influence of Cape gooseberry (CG) addition at different concentrations (5, 10 and 15%) on the physical, chemical and sensory properties and mineral contents of ice cream was investigated. The increment of CG concentration caused the decrease of fat, protein, pH and overrun values in ice cream, on the contrary it increased the total solid, ash, titratable acidity, viscosity values and first dripping and complete melting times. S contents of ice creams significantly increased with the CG addition. Moreover, CG increased K, and Na concentrations of ice cream, while lowered Ca and P contents. Mg contents of ice creams didn't change with CG addition (P > 0.05). Fe, Zn, Mn and Ni were determined as minor elements in ice cream samples and a significant increase was observed in Fe, Zn and Mn values (P < 0.05). The addition of CG did not affect Ni content of ice creams. The sensory results indicated that the ice cream containing 15% CG was the highest-scored by the panelists.  相似文献   

2.
《International Dairy Journal》2002,12(2-3):201-208
After several studies have proved the benefits deriving from the ingestion of probiotic bacteria, various dairy products containing lactobacilli and bifidobacteria cultures have been formulated in recent years. A 24 full factorial experimental design was applied to verify the effects of Lactobacillus johnsonii La1 addition in retail-manufactured ice cream stored at two different freezing temperatures and containing two different levels of sugar and fat. Both fresh and frozen–thawed La1 cells underwent preliminary resistance tests to bile, antibiotics, SDS, and acidity. La1 strain proved to be highly resistant to most of stress factors, thus excluding the possibility to find evidence of cell sublethal injuries caused by freezing. When the microorganism was added to ice cream mixes in the quantity of 107 cfu g−1, it did not modify the overrun and firmness of the finished product. Regardless of formulation, no count decay of La1 cells was observed in ice cream stored for up to 8 months.  相似文献   

3.
《International Dairy Journal》2006,16(10):1181-1189
The viability of Lactobacillus acidophilus LAFTI® L10, Bifidobacterium lactis LAFTI® B94, and L. paracasei LAFTI® L26 and their proteolytic activities were assessed in yoghurt at different termination pH of 4.45, 4.50, 4.55, and 4.60 in the presence of L. delbrueckii ssp. bulgaricus Lb1466 and Streptococcus thermophilus St1342 during 28 days of storage at 4 °C. All strains achieved the recommended level of 6.00 log cfu g−1 of the product with L. acidophilus LAFTI® L10 and L. paracasei LAFTI® L26 exceeding the number to 8.00 and 7.00 log cfu g−1, respectively. Lactobacilli strains showed a good cellular stability maintaining constant concentration throughout storage period regardless of termination pH. On the other hand, the cell counts of B. lactis LAFTI® B94 decreased by one log cycle at the end of storage. The presence of probiotic organisms enhanced proteolysis significantly in comparison with the control batch containing L. delbrueckii ssp. bulgaricus Lb1466 and S. thermophilus St1342 only. The proteolytic activity varied due to termination pH, but also appeared to be strain related. The increased proteolysis improved survival of L. delbrueckii ssp. bulgaricus Lb1466 during storage resulting in lowering of pH and production of higher levels of organic acids, which might have caused the low cell counts for B. lactis LAFTI® B94.  相似文献   

4.
《International Dairy Journal》2005,15(10):1056-1063
Low-field 1H nuclear magnetic resonance (NMR) transverse relaxation (T2) was measured during cooling (31–4 °C) of cream with low or high content of long-chain fatty acids (FA). Distributed analysis of the T2 relaxation data revealed marked differences in the T2 relaxation characteristics of the liquid fat population (10–100 ms), which was ascribed to differences in the size of the fat globules in the two types of cream. Principal component analysis (PCA) of the obtained T2 relaxation decay data showed clear shifts in NMR relaxation behavior at 17 and 22 °C for cream with low or high content of long-chain FA, respectively. Differential scanning calorimetric measurements on the creams revealed that these shifts took place at the onset of crystallization of fat. Consequently, the present study demonstrated that low-field NMR can be used to measure phase transitions in cream.  相似文献   

5.
This research investigated the possibility of uncovering a relationship between the sensitivities of trained and consumer panels in three experiments. In Experiment I, five studies were conducted using vanilla flavored ice cream. In each study, two ice cream samples differing in formulation and/or their manufacturing process were used. They were compared by both panels using same–different tests with sureness judgments (degree of difference methodology). Using the appropriate probabilistic Thurstonian model, d′ values, a measure of the underlying sensory difference perceived between the products, were calculated and the underlying relationship between the two panels’ sensitivities uncovered. An additional study was then conducted (Experiment II). A new pair of ice creams differing in fat content was first evaluated by the trained panel. Based on the estimated d′ value (trained panel’s measured d = 2.69), the corresponding consumer d′ value was predicted using the relationship uncovered in Part I (consumer panel’s predicted d = 1.54). The same pair of ice creams was then evaluated by the consumer panel. The measured d′ value for the consumers was almost identical to that predicted by the uncovered relationship (consumer panel’s measured d = 1.56). Along with the discrimination component of these studies, paired preference tests were conducted (Experiment III) in order to study a link between perceived difference and expressed preference. The results give an indication of when a perceived difference might start translating into a change in acceptability of the original product. These results indicate the potential of such an approach to predict consumers’ perceptions from an in-house semi-trained or trained panel, providing a useful predictive tool and a means of reducing repetitive and costly consumer testing.  相似文献   

6.
The goal of this work was to investigate the physicochemical properties of methylcellulose (MC) based films as stabilizers of two strains of lactobacilli: Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333 and Lactobacillus plantarum CIDCA 83114. The incorporation of 3% w/v fructo-oligosaccharides (FOS) into the MC film formulation improved the viability of L. delbrueckii subsp. bulgaricus CIDCA 333 after film preparation. L. plantarum CIDCA 83114 was intrinsically more resistant as no viability loss was observed upon preparation of the films in the absence of FOS.Scanning electronic microscopy images also showed a good incorporation of microorganisms without affecting the homogeneity of the films. FTIR spectroscopy provided structural information about the bacteria-loaded films. Water sorption isotherms showed an impervious behavior at low aw but on exceeding 0.7 of aw the film started to dissolve and form syrup, causing a drastic drop of bacterial viability (log N/N0   5). Dynamic mechanical analysis (DMA) demonstrated that the incorporation of microorganisms into the MC films had no effect on vitreous transition temperatures. FOS incorporated into the MC films had a plasticizing effect.Microorganism-loaded films were stored at relative humidities (RH) ranging from 11 to 75%. Both strains could be stored at 11% RH for 90 days. At 33 and 44% RH L. delbrueckii subsp. bulgaricus CIDCA 333 could be stored up to 15 days and L. plantarum CIDCA 83114 up to 45 days. At 75% RH only L. plantarum CIDCA 83114 could be equilibrated (log N/N0: − 2.05 ± 0.25), but CFU/g films were undetectable after 15 days of storage.The results obtained in this work support the use of MC films containing FOS as a good strategy to immobilize lactic acid bacteria, with potential applications in the development of functional foods.  相似文献   

7.
Ice cream mix was produced with a range of emulsifiers and concentrations. Ice cream mix properties were measured and correlated to ice cream properties. Protein load (mg m−2) in ice cream mix correlated with major characteristic analyses describing the fat structure in ice cream (fat agglomerate size, fat agglomeration index, solvent extractable fat). Thus, the measurement of protein load in the mix can be used to predict ice cream fat stability and related structure with constant processing conditions. As emulsification increased, more fat could be seen at the air interface by scanning electron microscopy. High correlation coefficients were also obtained with fat structure analyses and the quantitative determination of fat in the dripped portion taken from a melting test of ice cream. Hence, fat analysis from the dripped melt fraction is suggested as a method to characterize the fat-related structure in ice cream.  相似文献   

8.
Ice cream prepared using a substantial amount of juice from kiwifruit with green, gold or red flesh may have consumer appeal, through the combination of kiwifruit's unique color, natural flavor and health-promoting constituents. The aqueous fractions from purees of kiwifruit with green, gold and red flesh (AFKWs) were added at 49% v/v to a basic low-fat ice cream mix that contained no commercial flavoring and coloring agents. The resultant ice creams were subjected to comparative product evaluation (e.g. overrun, melting behavior and rheological properties) and chemical analyses of bioactives (e.g. total extractable polyphenol content (TEPC), vitamin C, antioxidant capacity, polyphenol (PP) and carotenoid composition). Results revealed that both the pH pre-adjustment and pre-heating of the AFKW played critical roles in ice cream making. The ice creams retained the PP and vitamin C contents as well as natural color flavor of the kiwifruit used. The rheological properties of all ice creams showed non-Newtonian flow behavior, and the storage modulus G′ decreased in the same pattern following the order of green > gold > red. The melting rate, overrun and vitamin C content of the ice cream with green AFKW were the fastest, lowest and least, respectively. The TEPC and antioxidant capacity in the ice cream with red AFKW were the highest. The amounts of PPs and vitamin C were encouragingly high. Health beneficial compounds, dimethyl-caffeic acid hexoside, caffeic acid derivatives, protocatechuic acid, syringic acid, salicylic acid/ο-coumaric acid, lutein and beta-carotene, were detected in the final products. Thus, there are commercial possibilities for using AFKW which should be further evaluated.  相似文献   

9.
《Food chemistry》2005,92(1):23-28
Lactobacillus delbrueckii ssp. bulgaricus (CCRC14009) and L. acidophilus (CCRC14079), immobilized with chitosan and polyacrylamide, were tested for CLA production. A 10-ml aliquot of L. delbrueckii ssp. bulgaricus cell suspension (3.59 × 107 CFU/ml) was adsorbed to 0.5 g chitosan and polyacrylamide, mixed with 0.2 ml linoleic acid (0.9 g/ml), and incubated at 37 °C for 24 h at pH 5, 6, 7, and 8 for CLA production. CLA levels, produced by immobilized cells of L. delbrueckii ssp. bulgaricus and L. acidophilus with increasing cell counts to 1.08 and 1.28 × 1010 CFU/ml, respectively, at optimal reaction pHs were evaluated. More CLA was formed at pH 8 of chitosan and pH 7 of polyacrylamide-immobilized L. delbrueckii ssp. bulgaricus cell treatments. Increase in cell count resulted in higher CLA production. The adsorption of L. delbrueckii ssp. bulgaricus cells onto polyacrylamide at pH 7 showed significant improvement in total CLA level. Results demonstrated a potential for enhancing CLA production through immobilization.  相似文献   

10.
Six different formulations, corresponding to three types of fat (hydrogenated or refined coconut oils or refined palm oil) and two mixtures of mono- and di-glycerides, namely saturated and partially unsaturated were chosen to investigate the influence of the oil phase nature and the low molecular weight emulsifier type on the networks present in ice cream. Ice creams were characterized for particle size distribution of fat globules, melting resistance and amount of proteins in the aqueous phase. Variation of rheological parameters as a function of temperature allowed following the ice network melting, the fat globule aggregation state and destabilization, and the structural arrangement of proteins. Presence of unsaturated fatty acids in the emulsifier promoted an increased percentage of agglomerated fat globules, increased melting time and higher storage modulus values at 5 °C. The influence of the fat type on ice cream characteristics was mainly illustrated by different rheological parameters and, to a lesser extent, by melting time, whereas the amount of proteins in the aqueous phase did not allow discriminating among the formulations.  相似文献   

11.
The amount of ice nuclei formed during the pressure release is important for the final formation and development of ice crystals in pressure shift freezing (PSF) frozen products. In this study, a high-pressure (HP) calorimeter was used to evaluate the ratio of ice crystals instantaneously formed by rapid depressurization during PSF of pure water and pork muscle tissue. Experiments were carried out initial pressure levels of 62, 115, 157 and 199 MPa, with corresponding phase change temperatures of −5, −10, −15 and −20 °C, respectively (slightly higher than phase change point of water–ice I). The ice crystal ratio was determined based on calorimetric peak measured and heat balance. The evaluated regression relationship between observed ice crystal ratio (Rice in %) and pressure (P, MPa) was Rice–water = 0.115P + 0.00013P2 (R2 = 0.96, n = 9) for pure water, and Rice–pork = 0.080P + 0.00012P2 (R2 = 0.95, n = 11) for pork muscle. Compared to other methods, the calorimetric evaluation does not require any of the pressure-related properties of the test sample. HP calorimetry can thus be used to evaluate ice crystal ratio for PSF of foods even though their pressure related properties may be unknown.  相似文献   

12.
《LWT》2005,38(1):21-28
This study evaluated dipping solutions of nisin with or without organic acids or salts, as inhibitors of Listeria monocytogenes introduced on sliced cooked pork bologna before vacuum packaging and storage at 4°C for 120 days. Inoculated (102–103 cfu/cm2) slices were immersed in nisin (5000 IU/ml), or in lactic or acetic acid (1, 3, 5 g/100 ml), sodium acetate or diacetate (3, 5 g/100 ml), and potassium benzoate or sorbate (3 g/100 ml), each combined with nisin. Additional slices were immersed in nisin, inoculated and then immersed in acid or salt solutions without nisin. Nisin reduced L. monocytogenes by 1.0–1.5 log cfu/cm2 at treatment (day-0) followed by a listeriostatic effect for 10 days. Thereafter, however, the pathogen multiplied in treatments without acid or salts, with growth being faster on slices immersed in nisin after as compared to before inoculation. Nisin in combination with 3 or 5 g/100 ml acetic acid or sodium diacetate or 3 g/100 ml potassium benzoate, applied individually or as mixtures, did not permit growth before day-90. Other treatments were of variable and lesser effectiveness (20–70 days), whereas in untreated or water-treated (control) bologna L. monocytogenes increased at 6–7 log cfu/cm2 at day-20. Based on the antilisterial efficacy and effects of treatments on product pH, nisin with 3 g/100 ml sodium diacetate may be the most promising combination in dipping solutions to control L. monocytogenes on sliced cured pork bologna.  相似文献   

13.
《International Dairy Journal》2005,15(6-9):921-927
Various foods may be used to deliver probiotic bacteria into the gastrointestinal tract; one such example is Requeijão, a Portuguese whey cheese. Survival and stability of Bifidobacterium animalis strains BLC-1, Bb-12, and Bo, Lactobacillus acidophilus strains LAC-1 and Ki, L. paracasei ssp. paracasei strain LCS-1 and L. brevis strain LMG 6906 inoculated into Requeijão, when exposed to simulated gastrointestinal tract conditions, were assessed. Homogenates of inoculated whey cheese in 0.85% (w/v) sterile saline water were exposed to a solution of hydrochloric acid (pH 2.5–3.0) and pepsin (1000 units mL–1) at 37 °C, and then to 0.3% (w/v) bile salts after 60 or 120 min of acid exposure. All bacterial strains retained their initial viable cell numbers. Bifidobacterium animalis strains Bb-12 and Bo, and L. brevis strain LMG 6906 exhibited the highest viable cell numbers when exposed to bile salts, whereas the other strains had variable death rates.  相似文献   

14.
Caffeic acid and gallic acid were tested as inhibitors of the decrease of volatile acetate esters, ethyl esters and terpenes during storage of a white wine and a model wine medium. Wine and model wine samples were analysed by SPME along with GC–MS. At t = 0, no effect on the concentration of any volatile was observed as a result of adding each phenolic acid in any of wine or model wine samples. Many esters, such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and linalool decreased during storage of Debina-white wine for up to 20 months. Caffeic acid and gallic acid at 60 mg/L inhibited the decrease of these volatiles. Isoamyl acetate, ethyl hexanoate and linalool decreased during storage of the model wine medium containing 0, 20 or 40 mg/L SO2. Caffeic acid and gallic acid inhibited the decrease of three volatiles; SO2 inhibited the decrease of isoamyl acetate and ethyl hexanoate. In some cases, SO2 increased the inhibitory action of two phenolic acids. The inhibitory action of caffeic acid and gallic acid was dose dependent in the range 0–60 mg/L. Caffeic acid was active at 7.5 mg/L while gallic acid at 15 mg/L.Present results indicate that caffeic acid and gallic acid may be taken into account as potent inhibitors of the disappearance of aromatic volatile esters and terpenes in wines at concentrations similar to those existing in wines.  相似文献   

15.
Production of carbonyl compounds by single-strain cultures, kefir starter (Lactobacillus delbrueckii subsp. bulgaricus HP1+Lb. helveticus MP12+Lactococcus lactis subsp. lactis C15+Streptococcus thermophilus T15+Saccharomyces cerevisiae A13) and kefir grains during fermentation and storage of kefir was studied. The content of carbonyl compounds produced by kefir starter was greater than that produced by kefir grains. The maximum acetaldehyde concentration (18.3 μg g−1) in kefir with starter culture was mainly due to the metabolic activity of Lb. delbrueckii subsp. bulgaricus HP1 isolated from kefir grains. The highest diacetyl production activity was recorded in the starter culture (1.87 μg g−1) and the single-strain culture St. thermophilus T15 (1.62 μg g−1), followed by Lb. helveticus MP12 (0.85 μg g−1) and Lc. lactis subsp. lactis C15 (0.42 μg g−1). The lactobacilli Lb. delbrueckii subsp. bulgaricus HP1 and Lb. helveticus MP12 produced acetone, which was not found in the cocci cultures. The presence of 2-butanone was related to the production ability of Lb. helveticus MP12. In comparison, Lc. lactis subsp. lactis C15 synthesized ethyl acetate more actively than the other single-strain cultures included in the starter. S. cerevisiae A13 produced ethanol and CO2 in amounts (3975 μg g−1; 1.80 g L−1) that lent cultured kefir distinctive flavour and aroma characteristic of authentic kefir.  相似文献   

16.
The aim of the study was to develop a symbiotic cottage cheese containing Lactobacillus delbrueckii UFV H2b20 and inulin, and to evaluate the survival of this bacterium when the cheese was exposed to conditions simulating those found in the gastro-intestinal tract. Throughout the entire whole shelf-life period of the cheese, the probiotic cell counts were higher than those recommended for probiotic products containing 5% of inulin. The probiotic bacterium exhibited satisfactory resistance to low pH values and to high concentrations of bile salts. The addition of probiotic cells and inulin generated no alterations in the physicochemical characteristics of cheese.  相似文献   

17.
Astaxanthin is a powerful antioxidant with various health benefits such as prevention of age-related macular degeneration and improvement of the immune system, liver and heart function. To improve the post-harvesting stability of astaxanthin used in food, feed and nutraceutical industries, the biomass of the high astaxanthin producing alga Haematococcus pluvialis was dried by spray- or freeze-drying and under vacuum or air at − 20 °C to 37 °C for 20 weeks. Freeze-drying led to 41% higher astaxanthin recovery compared to commonly-used spray-drying. Low storage temperature (− 20 °C, 4 °C) and vacuum-packing also showed higher astaxanthin stability with as little as 12.3 ± 3.1% degradation during 20 weeks of storage. Cost-benefit analysis showed that freeze-drying followed by vacuum-packed storage at − 20 °C can generate AUD$600 higher profit compared to spray-drying from 100 kg H. pluvialis powder. Therefore, freeze-drying can be suggested as a mild and more profitable method for ensuring longer shelf life of astaxanthin from H. pluvialis.  相似文献   

18.
《Food microbiology》2004,21(2):157-165
The effect of filleting on microbiological, chemical, and sensory properties of aquacultured freshwater trout (Onchorynchus mykiss) stored in ice was studied. Pseudomonads, H2S-producing bacteria (including Shewanella putrefaciens) and Brochothrix thermosphacta were the dominant bacteria while, Enterobacteriaceae in lower counts were also found in the spoilage microflora of whole ungutted and filleted trout over an 18-day storage period in ice. Bacterial counts of whole ungutted trout were always lower than those obtained for filleted trout samples. Mesophilic counts for filleted and ungutted fish exceeded 7 log cfu/cm2 after 10 and 18 days of ice storage, respectively. Of the chemical indicators of spoilage, trimethylamine (TMA) values of ungutted trout increased very slowly whereas for filleted samples higher values were obtained reaching a final value of 4.29 and 6.38 mg N/100 g, respectively (day 18). Total volatile basic nitrogen (TVB-N) values showed no significant increase for whole ungutted trout during storage reaching a value of 20.16 mg N/100 g (day 18) whereas for filleted fish a respective value of 26.06 mg N/100 g was recorded. Thiobarbituric acid (TBA) values of ungutted trout increased very slowly whereas for filleted samples higher values were obtained reaching a final value of 16.21 and 19.41 μg MA/g, respectively (day 18). Of the chemical indices used, none proved useful means of monitoring early freshness for ungutted and filleted trout freshness in ice. Sensory assessment using the EC freshness scale gave a grade E for up to 6 days for the ungutted trout, a grade A for a further 3 days and a grade B for an additional 6 days, after which trout was graded as C (unfit). Acceptability scores for odor, taste and texture of cooked ungutted and filleted trout decreased with time of storage. Results of this study indicated that the shelf-life of whole ungutted and filleted trout stored in ice as determined by sensorial and microbiological data is 15–16 and 10–12 days, respectively.  相似文献   

19.
The present study investigated the effect of active and modified packaging as well as packaging material oxygen permeability on quality retention of dark chocolate with hazelnuts. Dark chocolate was packaged in: a) polyethylene terephthalate//low density polyethylene (PET//LDPE), and b) polyethylene terephthalate coated with SiOx//low density polyethylene (PET-SiOx//LDPE). Samples were packaged either under, vacuum or N2 or with an oxygen absorber and stored in the dark at 20 °C for a period of 12 months. “Commercial” control samples for comparison purposes consisted of chocolate packaged in aluminum foil in air while “model” control samples used for sensory evaluation consisted of chocolate packaged in glass jars and stored at ? 18 °C. Quality parameters monitored were: peroxide value, hexanal content, color, fatty acid composition and volatile compounds. Of the sensory attributes color, texture, odor and taste were evaluated. PV ranged between 0.80 for fresh dark chocolate with hazelnuts and 6.51 meq O2/kg chocolate fat for commercially packaged samples after 12 months of storage. Respective values for hexanal were 0.53 and 7.56 mg/kg. % Saturated fatty acids (SFA) increased with a parallel decrease in monounsaturated fatty acids (MFA) and polyunsaturated fatty acids (PUFA) after 12 months of storage mainly in least protected samples (commercial package). Likewise, after 12 months of storage an increase in concentration of aldehydes, ketones, alcohols and alkanes (p < 0.05) with a parallel decrease in pyrazines where observed especially in case of least protected products after 6 and 12 months of storage. In general after 12 months of storage chocolate showed whitening of the surface resulting to an increase in L* and a* values (p < 0.05) and a decrease in b* value. Dark chocolate with hazelnuts retained acceptable quality for ca. 8 months in commercial packages. For samples packaged in PET//LDPE irrespective of storage atmosphere the shelf life was 8 to 9 months and for samples packaged in PET-SiOx//LDPE irrespective of storage atmosphere the shelf life was 11 months. Finally for samples packaged with an oxygen absorber irrespective of packaging material the shelf life was at least 12 months.Industrial relevanceChocolate packaged with an oxygen absorber in a barrier packaging material will maintain its aroma, taste and nutritional quality substantially longer than other packaging methods.  相似文献   

20.
In order to investigate the impact of common food ingredients on catechin absorption, green tea (GT) extract (50 mg) was formulated plain, with sucrose (GT + S), with ascorbic acid (GT + AA) and with sucrose and ascorbic acid (GT + S + AA). Bioavailability and bioaccessibility were assessed in Sprague Dawley rats and an in vitro digestion/Caco-2 cell model respectively. Absorption of epigallocatechin (EGC) and epigallocatechin gallate (EGCG) was significantly (P < 0.05) enhanced in GT + S + AA formulations (AUC0–6 h = 3237.0 and 181.8 pmol h/L plasma respectively) relative to GT control (AUC0–6 h = 1304.1 and 61.0 pmol h/L plasma respectively). In vitro digestive recovery was higher for EGC and epicatechin (EC) (~51–53%) relative to EGCG and epicatechin gallate (ECG) (<20%) and was modestly enhanced in GT + S and GT + S + AA formulations. Accumulation of EGC, EGCG and ECG by Caco-2 cells was significantly (P < 0.05) higher from GT + S + AA compared to other formulations while retention of catechins was enhanced in presence of ascorbic acid. These data suggest that formulation with sucrose and ascorbic acid may improve catechin bioavailability by enhancing bioaccessibility and intestinal uptake from tea.  相似文献   

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