Showing papers in "Lwt - Food Science and Technology in 2005"
TL;DR: GO components did not affect the physical and mechanical properties of chitosan films as it did not have any interaction with the functional groups of chITosan as measured by FTIR.
Abstract: Antimicrobial effect of chitosan edible film incorporating garlic oil (GO) was compared with conventional food preservative potassium sorbate (PS) and bacteriocin nisin (N) at various concentrations. This activity was tested against food pathogenic bacteria namely Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Listeria monocytogenes and Bacillus cereus. Mechanical and physical properties were characterized and Fourier Transform Infrared (FTIR) was also performed to determine functional groups interactions between the matrix and added agent. Incorporation of GO up to levels at least 100 μl/g, PS at 100 mg/g or N at 51,000 IU/g of chitosan were found to have antimicrobial activity against S. aureus, L. monocytogenes, and B. cereus. At these levels, the films were physically acceptable in term of appearance, mechanical and physical properties. GO components did not affect the physical and mechanical properties of chitosan films as it did not have any interaction with the functional groups of chitosan as measured by FTIR.
569 citations
TL;DR: The essential oil with the lowest MIC and MBC was clove and the results demonstrated that clove exerted a significant bactericidal and bacteriostatic action.
Abstract: Technological application of essential oils, as natural sanitizing agents, to reduce food pathogens in the post-harvest processing of foods requires the establishment of the optimal conditions. The present work evaluated the parameters of antimicrobial activity of the essential oils of eucalyptus ( Eucalyptus globules ), tea tree ( Melaleuca alternifolia ), rosemary ( Rosmarinus officinalis ), mint ( Mentha piperita ), rosa moschata ( Rosa moschata ), clove ( Syzygium aromaticum ), lemon ( Citrus limonum ), oregano ( Origanum vulgare ), pine ( Pinus silvestrys ) and sweet basil ( Ocimum basilicum ) on survival and growth of different strains of E. coli O157:H7. The strains of E. coli exhibited similar susceptibilities to the action of the essential oils assayed. The essential oil with the lowest MIC and MBC (Minimum Inhibitory and Bactericidal Concentration, respectively) was clove (0.25 ml/100 ml and 0.3 ml/100 ml, respectively) and the results demonstrated that clove exerted a significant bactericidal and bacteriostatic action.
402 citations
TL;DR: The antioxidant properties of the fresh and blanched green leafy vegetables were subsequently determined in this article, where the total phenol, ascorbic acid and the antioxidant potentials as typified by reducing property and free radical scavenging activity was also determined.
Abstract: Eight popularly consumed green leafy vegetables in Nigeria namely: Structium sparejanophora, Amarantus cruentus, Telfairia occidentalis, Baselia alba, Solanum macrocarpon, Corchorus olitorus, Vernonia amygdalina, and Ocimum gratissimum were blanched in hot water for 5 mins. The antioxidant properties of the fresh and blanched green leafy vegetables were subsequently determined. The total phenol, ascorbic acid and the antioxidant potentials as typified by reducing property and free radical scavenging activity was also determined. The results of the study revealed that blanching cause a significant ( P Amarantus cruentus and Vernonia amygdalina where there was no change. Conversely, there was a significant ( P Structium sparejanophora, where there was no change in the reducing property (0.6 absorbance) and free radical scavenging ability (59.8%) of the blanched vegetable. In view of this it could be concluded that blanching of vegetables though makes green leafy vegetables more palatable and less toxic, however it reduces their antioxidant properties drastically.
320 citations
TL;DR: In this article, an integrated study was conducted on the effects of temperature and pH on the solubility of whey proteins, and the results showed that both conditions had great interaction.
Abstract: An integrated study was conducted on the effects of temperature and pH on the solubility of whey proteins. The solubility was determined experimentally in the range of 40–60°C for temperature and 3.5–7.8 for pH. The results showed that, both temperature and pH influenced in the protein solubility, and these properties had great interaction. Besides, for whey proteins, the solubility values were minimum at the pH value of 4.5, which is the isoelectric point of whey proteins, for all temperature values. It was also observed that at pH 4.5, the solubility decreased as the temperature increased, which indicated that the protein denaturation occurred. This behavior was also noticed in the neutrality (pH=6.8).
303 citations
TL;DR: In this paper, chemical composition of 13 locally available underutilized green leafy vegetables (GLV) was the objective of a study, and the results showed that four GLV had high iron content (13.15-17.72% of total carotene content) while the rest had lower levels (2.62-9.86%).
Abstract: Analysis of chemical composition of 13 locally available underutilized green leafy vegetables (GLV) was the objective of this study. Moisture, ash and ether extract of the greens were in the range of 73–95 g/100 g, 0.77–3.54 g/100 g and 0.2–0.9 g/100 g, respectively. Four GLV had high iron content (13.15–17.72 mg/100 g) while the rest had lower levels (2.62–9.86 mg/100 g). Calcium content varied largely between the greens ranging from 41 mg/100 g in Polygala erioptera to 506 mg/100 g in Digera arvensis, whereas phosphorous ranged from 16 to 63 mg/100 g. Ascorbic acid was higher in Delonix elata (295 mg/100 g) and Polygala erioptera (85 mg/100 g) and lower in others (3–46 mg/100 g). Thiamine was found to be less than 0.1 mg/100 g in six greens and 0.1–0.33 mg/100 g in others. Total carotene content ranged between 10 and 35 mg/100 g in all with exceptionally high amount in Cocculus hirsutus (67 mg/100 g) and Delonix elata (60 mg/100 g). β -carotene was 13–25% of total carotene in all greens. Oxalate content was below 100 mg/100 g in five greens and less than 1400 mg/100 g in the remaining GLV. Tannin content ranged between 61 and 205 mg/100 g in all GLV with the exception of Coleus aromaticus (15 mg/100 g) and Delonix elata (1330 mg/100 g).
263 citations
TL;DR: In this article, the authors evaluated the physical and chemical attributes of coffee beans of different qualities, both green and roasted, and concluded that the presence of defective coffee beans is quite relevant to coffee quality.
Abstract: One of the most important criteria used for assessing coffee quality is based on sensory analysis and is referred to as cup quality. The presence of defective coffee beans is quite relevant to coffee quality. However, the majority of data on coffee properties are restricted to supposedly good quality beans. Therefore, the present study is aimed at an evaluation of physical and chemical attributes of coffees of different qualities, both green and roasted. Arabica coffee samples, previously classified by cup as soft (higher quality), hard, rioysh and rio (lower quality), were roasted at 200 °C for 1 h. Regarding attributes of green coffee beans, both bean density and volume were higher for the soft sample compared to the rio one. The soft sample also presented higher protein levels, due to its higher caffeine contents. The rio sample presented lower lipid contents, probably associated to the presence of defective beans. Acidity increased and pH levels decreased as cup quality decreased, probably due to the effect of defective beans that undergone fermentation (sour beans). After roasting, the rio sample presented higher density and trigonelline levels, indicating that it did not roast to the same degree as the other samples.
218 citations
TL;DR: In this paper, the solubility, apparent viscosity, emulsifying activity, whippability and gel-forming ability of soy protein hydrolysates were determined.
Abstract: Soy protein hydrolysates were produced from a soy protein isolate (SPI) in which either the glycinin or β-conglycinin fractions had been selectively hydrolysed. The solubility, apparent viscosity, emulsifying activity, whippability and gel-forming ability of each hydrolysate were determined. Both hydrolysates had minimum solubility at around the same level of pH 4.5 as that of SPI. The reduced-β-conglycinin hydrolysate (RCH) showed lower apparent viscosity than the reduced-glycinin hydrolysate (RGH). Increased whippability was observed with both hydrolysates in comparison with SPI, whereas lower emulsifying activity was found, except at acidic pH 4. RCH retained more gel-forming ability than RGH when determined by mixing with salt-soluble meat protein. This result was supported by observation of the microstructure of the gels.
215 citations
TL;DR: In this article, the effect of a methyl cellulose-based coating on the respiration rate, color and texture of avocados stored at room temperature was evaluated by measuring the rate of CO 2 produced from a given quantity of fruits per unit time.
Abstract: Edible coatings regulate water vapor, oxygen and carbon dioxide transfer in or out of the produce thereby influencing the ongoing respiratory activity and produce quality. The objective of this study was to evaluate the effect of a methyl cellulose-based coating on the respiration rate, color and texture of avocados stored at room temperature. Avocados were initially surface disinfected, washed and air-dried. They were then immersed in the coating solution for 1 min at 20 °C, air-dried for 10 min and stored at 20 °C in an open box. At 2-day intervals, fruits were removed and evaluated for respiration rate, color and texture. Respiration rate was evaluated by measuring the rate of CO 2 produced from a given quantity of fruits per unit time. Color and texture of avocados were measured using instrumental techniques. Coated avocados demonstrated lower respiration rates, greener color and higher firmness as compared with the uncoated control during the entire storage. The appearance of brown spots and mesocarp discoloration normally associated with fruit ripening were delayed in the coated fruits.
198 citations
TL;DR: In this article, beet juice was evaluated as a potential substrate for the production of probiotic beet juice by four species of lactic acid bacteria (Lactobacillus acidophilus, Lactic acid casei, Lactobactactus delbrueckii, and Lactebacillus plantarum).
Abstract: Red beets were evaluated as a potential substrate for the production of probiotic beet juice by four species of lactic acid bacteria (Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus plantarum). All the lactic cultures were found capable of rapidly utilizing beet juice for cell synthesis and lactic acid production. However, L. acidophilus and L. plantarum produced a greater amount of lactic acid than other cultures and reduced the pH of fermented beet juice from an initial value of 6.3 to below 4.5 after 48 h of fermentation at 30°C. Although the lactic cultures in fermented beet juice gradually lost their viability during cold storage, the viable cell counts of these lactic acid bacteria except for L. acidophilus in the fermented beet juice still remained at 106–108 CFU/ml after 4 weeks of cold storage at 4°C.
198 citations
TL;DR: In this article, the effect of sorbate present on mechanical properties of edible films prepared with suspensions of tapioca starch containing glycerol, was studied with a Dynamic Mechanical Thermal Analyzer.
Abstract: The effect of sorbate present on mechanical properties of edible films prepared with suspensions of tapioca starch containing glycerol, was studied. Films were prepared by casting the systems after gelatinization. The storage modulus ( E ′) and the tangent of the phase angle (tan δ ) of the film pieces were determined with a Dynamic Mechanical Thermal Analyzer along 8 weeks of storage at a relative humidity (RH) of 57.5% and at 25 °C. Stress–strain behavior along quasi-static tests was also analysed using the same device. Results obtained showed that sorbate incorporation resulted in a decrease (≅75%) of E ′ and an increase (≅200%) of tan δ after 2 weeks of storage. Antimicrobial presence also affected film performance along storage: it showed a continuous decrease of tan δ along 8 weeks storage as well as an increase in the tendency to rupture with time. Films without sorbate showed an increase of tan δ along 4 weeks and they presented rupture for all storage periods studied. Aging of starch, characteristics of the network as well as sorbate destruction along storage, are responsible for the changes observed in mechanical properties of the film along 8 weeks.
165 citations
TL;DR: In this paper, the role of chitosan coating in inhibiting skin browning and extending shelf life of cold-stored litchi fruit at ambient temperature was investigated.
Abstract: Postharvest pericarp browning of litchi fruit results in an accelerated loss in shelf life and a reduced commercial value. Visual quality was lost in only 6 h at ambient temperature when fruit were removed from storage at 2 °C, due to browning. The experiment was conducted to test the role of chitosan coating in inhibiting skin browning and extending shelf life of cold-stored litchi fruit at ambient temperature. Litchi fruit were treated with 2 g chitosan/100 g solution and then stored for 20 days at 2 °C and 90–95% relative humidity (RH), prior to shelf life evaluation at 25 °C and 80–90% RH. Changes in polyphenol oxidase (PPO) activity, anthocyanin concentration, colour index, eating quality and concentrations of total soluble solids and titratable acidity were measured. The effects of chitosan coating on disease incidence were also evaluated. Application of chitosan coating delayed the decrease in anthocyanin content, the increase in PPO activity and the changes in colour index and eating quality, reduced the decrease in concentrations of total soluble solids and titratable acidity, and partially inhibited decay. The results suggested that treatment with chitosan coating exhibited a potential for shelf life extension at ambient temperature when litchi fruit were removed from cold storage.
TL;DR: In this article, a process for producing xylooligosaccharides from corncob was developed, which consisted of soaking the cncob in 1.0g/l H 2 SO 4 at 60°C for 12h, followed by filtrating and washing with tap water to pH 6 and steaming at 135-140 °C for 0.5h.
Abstract: Xylooligosaccharide, which is usually produced from xylan by enzymatic hydrolysis, is a newly developed functional oligosaccharide having many beneficial biomedical and health effects. In this study, a process for producing xylooligosaccharides from corncob was developed. The procedure consisted of soaking the corncob in 1.0 g/l H 2 SO 4 at 60 °C for 12 h, followed by filtrating and washing with tap water to pH 6 and steaming at 135–140 °C for 0.5 h. The steamed corncob was mashed and hydrolysed by xylanase. The cumulative yield of xylooligosaccharides after enzymatic hydrolysis was close to 67.7 g/100 g by steaming (based on xylan in raw material), and the purity of xylooligosaccharides was over 70 g/100 g (based on the total sugars in the hydrolysate). This study demonstrated that the xylan–lignin complex present in the corncob was affected during steaming at 135 °C for 30 min. Almost all of the xylan was removed from the lignin after steam application and subsequent enzymatic hydrolysis.
TL;DR: In this paper, the effect of pre-drying treatment on texture evolution and oil uptake of blanched potato slices during frying was investigated, and the results showed that predrying significantly decreased the oil absorption and significantly increased the crispness of the slices after frying.
Abstract: The objective of this work was to determine the effect of the pre-drying treatment over the texture evolution and the oil uptake of blanched potato slices during frying. Prior to frying, potato slices (Panda variety, diameter: 37 mm, width: 2.2 mm) were blanched in hot water at 85 °C for 3.5 min. Blanched potato slices were used as the control. Some blanched slices were additionally air-dried until reaching moisture contents of ∼60 g/100 g—wet basis—(slices blanched–dried). Either only blanched or blanched–dried potato slices were fried at 120, 150 and 180 °C until reaching final moisture contents of ∼1.8 g/100 g (wet basis). The texture and oil content of the slices were measured periodically during frying. Normalized Maximum Force (MFn) was the parameter used to model the textural changes in the potato slices during frying in both the initial tissue softening process and the later crust development process. Both the frying temperature and the pre-drying treatment had a significant effect ( P >0.05) over the final texture and oil content of the fried potato chips. When frying at 120 °C, potato chips were crispier and contained more oil than potato chips fried at 180 °C. Pre-drying dramatically decreased the oil absorption and significantly increased ( P >0.05) the crispness of the blanched potato slices after frying.
TL;DR: In this paper, the authors used microwave, halogen lamp-microwave combination and hot-air drying to dry carrots to 0.47 kg moisture/kg dry solid.
Abstract: Carrot slices were dried by using microwave, halogen lamp–microwave combination and hot-air drying. Microwave and halogen lamp–microwave combination drying were applied after carrots were dried to 0.47 kg moisture/kg dry solid by hot-air drying. Drying time, rehydration capacity and colour of the carrots dried by different methods were compared. The increase in microwave oven power level decreased the drying time. Microwave drying at the highest power and halogen lamp–microwave combination drying reduced the drying time to an extend of 98% in comparison to conventional hot-air drying and a high-quality dried product was obtained. Moreover, in the case of halogen lamp–microwave combination drying, moisture level was reduced to a level, which is lower than the one achieved by other methods. Less colour change occurred when microwave and halogen lamp–microwave combination drying were applied. Carrots dried in microwave and halogen lamp–microwave combination oven had lower L*, higher a* and b* values and had higher rehydration capacity as compared to hot-air drying.
TL;DR: In this paper, the oxidative and hydrolytic degradation of lipids in fish oil was monitored using partial least squares regression and near-infrared reflectance (NIR) spectroscopy.
Abstract: The oxidative and hydrolytic degradation of lipids in fish oil was monitored using partial least-squares (PLS) regression and near-infrared reflectance (NIR) spectroscopy. One hundred and sixty (n=160) fish oil samples from a fishmeal factory were scanned in transflectance by an NIR monochromator instrument (1100–2500 nm). Calibration models were performed for free fatty acids (FFA), moisture (M), peroxide value (PV) and anisidine value (AV). Coefficients of determination in calibration (R2) and standard errors of cross validation (SECV) were 0.96 (SECV: 0.59) and 0.94 (SECV: 0.03) for FFA and M in g/kg, respectively. The accuracy of the NIR calibration models were tested using a validation set, yielding coefficients of correlation (r) and standard errors of prediction (SEP) of 0.98 (SEP: 0.50) and 0.80 (SEP: 0.05) for FFA and M in g/kg, respectively. Poor accuracy (R2
TL;DR: In this paper, a Brabender single extruder (20:1 l/D) was used to modify the functional and structural properties of the fibre, and the extrusion process increased the water absorption index (34.86g/100g), water solubility index (134 g/100 g), and swollen volume (43.75 g/ 100 g).
Abstract: Orange pulp was extruded using a Brabender single extruder (20:1 l/D) so as to modify the functional and structural properties of the fibre. The independent variables studied were: barrel temperature (83°C, 100°C, 125°C, 150°C, and 167°C), moisture content (22, 25, 30, 35, and 38 g/100 g), and screw speed (126, 140, 160, 180, and 194 rpm). The feed speed was kept constant at 70 g/min. The compression ratio was 3:1, and the die diameter was 4 mm. The extrusion process increased the water absorption index (34.86 g/100 g), water solubility index (134 g/100 g), and swollen volume (43.75 g/100 g) and these variables were significantly influenced by the feed moisture content of the raw material and by the barrel temperature. The extruded orange pulp had 74.87 g/100 g total alimentary fibre, 54.81 g/100 g insoluble alimentary fibre and 20.06 g/100 g soluble alimentary fibre. Biscuits of good technological quality and with a good level of acceptance were obtained by means of replacing up to 15 g/100 g of the wheat flour with extruded orange pulp. The energy value of the biscuits decreased with increased extruded orange pulp content, with reductions of 2.95, 6.62, and 10.67 g/100 g in total calories as compared to the control.
TL;DR: In this paper, eight improved haricot bean varieties were studied for their proximate composition and physico-chemical properties, including moisture, ash, crude protein, crude lipid, crude fiber, crude fat, total carbohydrates, total energy, mineral content, physico chemical properties.
Abstract: Eight improved haricot bean varieties were studied for their proximate composition and physico-chemical properties. The nutrition related parameters studied were moisture, ash, crude protein, Crude lipid, crude fiber, crude fat, total carbohydrates, total energy, mineral content and physico-chemical properties. The physico-chemical properties analysed included density, 100-seed mass, water hydration capacity, swelling capacity, hydration index, swelling index, swelling and hydration coefficient, cooking time, color and cooked texture. Protein content ranged between 17.96 and 22.07 g/100 g with significant differences among improved varieties. Crude fat ranged 1.27–3.02 g/100 g, crude fiber 4.66–5.95 g/100 g, ash 2.86–4.26 g/100 g, carbohydrates 56.53–61.56 g/100 g, moisture content 9.08–11.00 g/100 g and lipid 0.67–1.19 g/100 g, respectively. Energy values of the seeds were 1320.01–1375.74 kJ/100 g (DM), which are comparable to those of other dry beans. Mineral contents of the seeds showed greater variation. Ca was the most abundant 1929.77 mg/kg whereas Zn was low 28.22 mg/kg. Considerable variations were observed among the varieties for calcium, phosphorus, iron and zinc contents. Large variations existed in cooking time, swelling capacity, hydration capacity, unhydrated seeds and hardness. The research results can be used for investigators and food companies for the recipe development of bean-based processed foods, including fortified products. The improved varieties Roba, Redwolaita, Awash and Mexican were found better food and export type varieties.
TL;DR: In this paper, the retention of lycopene during spray drying of tomato pulp and study the effect of drying conditions on the Lycopene content of tomato powder were conducted keeping constant the feed rate, the feed temperature and the atomizer pressure, and varying the compressed air flow rate.
Abstract: Lycopene is the principal pigment found in tomatoes and is important not only because of the color it imparts but also because of the recognized health benefits associated with its presence. Degradation of lycopene not only affects the attractive color of the final products but also their nutritive value. The objectives of this study were to determine the retention of lycopene during spray drying of tomato pulp and study the effect of drying conditions on the lycopene content of tomato powder. Sixty-four different experiments were conducted keeping constant the feed rate, the feed temperature and the atomizer pressure, and varying the compressed air flow rate, the flow rate of drying air and the air inlet temperature. Tomato powders were analysed for lycopene content. Lycopene content varied from 1016.05 to 1181.30 μg/g total solids, whereas lycopene loss ranged between 8.07 and 20.93%. Analysis of experimental data yielded correlations between lycopene retention and the variable operating conditions. Lycopene loss increased with increases in air inlet temperature and in both drying and compressed air flow rate. Multiple regression analysis was used to develop a predictive equation for final lycopene retention during spray drying. The decrease in lycopene content reported here was due to an actual degradation of lycopene, rather than to a progressive conversion from the all- trans -lycopene to a less strongly colored, less intensely absorbing cis form.
TL;DR: In this paper, the effects of systematically varied blends of lecithin and polyglycerol polyricinoleate (PGPR) added in a concentration up to 14g/kg on the flow properties of melted dark and milk chocolate were determined by means of rotational rheometry.
Abstract: Lecithin and polyglycerol polyricinoleate (PGPR) are common emulsifiers used in the manufacture of chocolate products. The effects of systematically varied blends of lecithin and PGPR added in a concentration up to 14 g/kg on the flow properties of melted dark and milk chocolate were determined by means of rotational rheometry. The results show that, independent of the total amount of the emulsifier, the yield stress of both dark and milk chocolate mass is most efficiently reduced by applying mixtures of approximately 30% lecithin and 70% PGPR. As regards total emulsifier concentrations between 4 and 6 g/kg, lowest viscosity values were found for lecithin–PGPR blends of 50:50 and 75:25 for dark chocolate and milk chocolate, respectively. The obtained results indicate that it is possible to tailor yield stress and viscosity of melted chocolate to specific requirements by the appropriate adjustment of both blending ratio and quantity of the emulsifiers.
TL;DR: In this paper, the influence of different cooking treatments on the quality characteristics of chicken breast slices was investigated by measuring shear force using instrumental texture analysis, and it was found that marination followed by air-steam cooking is the best combination to obtain the most tender chicken slices.
Abstract: The influence of different cooking treatments on tenderness and cooking loss, as main quality characteristics of chicken breast meat, was investigated Industrial skinless chicken breast meat samples were designated as raw and marinated and cooked in the oven by hot air and hot air-steam mixture at 130, 150 and 170 °C, for 4, 8 and 12 min Cooking losses were evaluated by weight changes before and after cooking, and tenderness changes were determined on cooked samples by measuring shear force using instrumental texture analysis Results showed that marination, followed by air-steam cooking is the best combination to obtain the most tender chicken breast slices The time and temperature of cooking showed similar effects on cooking loss and tenderness: short cooking time (4 min) and temperatures of 130–150 °C resulted in lower cooking losses and best meat tenderness, in both not marinated and marinated meat Statistically significant correlations between tenderness and cooking loss indicated that the cooking loss correlated better with cooking time than with cooking temperature An opposite phenomenon was observed for meat tenderness
TL;DR: To achieve a good coloured strawberry jam with high antioxidant capacity, the industry should consider to store the products at 4 °C and to replace ‘Senga Sengana’ with one of the ‘Korona’, ‘Honeoye’ and ‘Polka’ cultivars.
Abstract: Jam was prepared from five strawberry cultivars; ‘Senga Sengana’, ‘Korona’, ‘Polka’, ‘Honeoye’ and ‘Inga’. The jam was stored at 4 and 20 °C, in darkness and under fluorescent light (950 lux). The quality parameters assessed were colour reflectance at 650 nm, Hunter L*,a*,b*, anthocyanin pigments and total antioxidant capacity assessed by FRAP-assay. Jam produced of all cultivars stored at 4 °C had significantly better colour qualities and FRAP-values than jam stored at 20 °C. The light conditions during storage did not affect the assessed quality parameters of the product during three months of storage. The cultivars ‘Senga Sengana’, ‘Korona’, ‘Honeoye’ and ‘Polka’ showed the highest a*-values (red colour), but only ‘Korona’, ‘Honeoye’ and ‘Polka’ showed a high total antioxidant capacity, as measured by FRAP and compared to ‘Senga Sengana’ and ‘Inga’. Thus, to achieve a good coloured strawberry jam with high antioxidant capacity, the industry should consider to store the products at 4 °C and to replace ‘Senga Sengana’ with one of the ‘Korona’, ‘Honeoye’ and ‘Polka’ cultivars.
TL;DR: The most frequently isolated species was found to be L. mesenteroides subsp.
Abstract: The microflora involved in production of suusac , a Kenyan traditional fermented camel milk product, were enumerated and identified. 15 samples of traditionally fermented suusac were analysed. Total viable microorganisms, lactic acid bacteria (LAB), yeasts and moulds, and coliforms were enumerated. A total of 45 LAB and 30 yeast isolates were isolated from the 15 suusac samples and identified by API 50 CHL and API 20C AUX identification systems, respectively. The LAB counts were 6.8 log 10 cfu/ml, while yeast and mould counts were relatively lower (2.1 log 10 cfu/ml). Low coliform numbers were encountered ( 10 cfu/ml). The LAB species were identified as Lactobacillus curvatus , Lactobacillus plantarum , Lactobacillus salivarius , Lactococcus raffinolactis and Leuconostoc mesenteroides subsp. mesenteroides . The isolated yeasts were identified as Candida krusei , Geotrichum penicillatum and Rhodotorula mucilaginosa. The most frequently isolated species was found to be L. mesenteroides subsp. mesenteroides (24% of total isolates), followed by C. krusei (20%) and L. plantarum (16%).
TL;DR: Vacuum drying and low-pressure superheated steam drying (LPSSD) of Indian gooseberry flake were carried out at various drying conditions to monitor the drying kinetics and quality degradation of the product during drying.
Abstract: Vacuum drying and low-pressure superheated steam drying (LPSSD) of Indian gooseberry flake (used to prepare Indian gooseberry tea) were carried out at various drying conditions to monitor the drying kinetics and quality degradation of the product during drying. In terms of drying kinetics, the vacuum drying took shorter time to dry the product than LPSSD at every drying condition. In terms of quality, it was found that only the product subjected to vacuum drying at 75 °C and absolute pressure of 7 kPa had similar level of ascorbic acid retention compared to those samples of LPSSD at every condition. The total color difference of this sample was, however, slightly higher than that of product dried by LPSSD. Nevertheless, since the color changes were not of much concern to the consumers of Indian gooseberry tea, vacuum drying at 75 °C and 7 kPa was proposed as the most favorable condition for drying of Indian gooseberry flake in terms of energy consumption.
TL;DR: In this article, the authors used scanning electron microscopy (SEM) to visualize the degree of structural damages caused, which depended on the crystal size and water movement, and concluded that the freezing-thawing conditions are responsible for the modifications observed.
Abstract: The selection of freezing conditions is very important in order to optimize the efficiency of the freezing process and simultaneously retain the biological microstructure. Fresh strawberry and osmotically dehydrated strawberry samples were frozen and thawed using several combinations of temperatures and air velocities. Different freezing and thawing rates were used, which resulted in varying degrees of mass transport from the intercellular to extracellular domain. Scanning electron microscopy (SEM) was used to visualize the degree of structural damages caused, which depended on the crystal size and water movement. SEM showed that better preservation of the structure was obtained using high freezing or thawing rates. When high temperatures were used for thawing, the tissue damage was greater and extensive. Pre-treatment with sucrose reduced the total mass of samples to about 2.5 g/100 g in the osmotically dehydrated samples but did not affect the tissue integrity. It is concluded that the freezing–thawing conditions are responsible for the modifications observed. By using this technique it was possible to establish relationships between the tissue structure and the processing conditions.
TL;DR: In this paper, the effect of a probiotic Lactobacillus paracasei culture on sensory performance and on the behaviour of instrumental texture profile and related properties of Minas fresh cheese during storage at 5 o C was investigated.
Abstract: The effect of a probiotic Lactobacillus paracasei culture on sensory performance and on the behaviour of instrumental texture profile and related properties of Minas fresh cheese during storage at 5 o C was investigated. Four cheese-making trials were prepared, two supplemented with a mesophilic type O lactic culture (T1, T2) and two with lactic acid (T3, T4). L. paracasei subsp. paracasei was added in T2 and T3. The viability of L. paracasei , instrumental texture profile analysis and related properties were monitored during storage for up to 21 days. Viable counts of L. paracasei in probiotic cheeses T2 and T3 started above 10 6 –10 7 cfu g −1 and increased during storage. Cheeses T1 and T2 differed significantly from T3 and T4 in relation to hardness, cohesiveness, chewiness and gumminess ( P L. paracasei showed a great potential as a functional food.
TL;DR: Ganoderma tsugae Murrill was available in the form of mature and baby Ling chih, mycelia and fermentation filtrate, and their antioxidant properties were studied as discussed by the authors.
Abstract: Ganoderma tsugae Murrill (Ganodermataceae) were available in the form of mature and baby Ling chih, mycelia and fermentation filtrate. From these four forms, hot water extracts were prepared and their antioxidant properties were studied. Hot water extracts from mature and baby Ling chih showed high antioxidant activities (78.5% and 78.2%) at 20 mg/ml, and had EC 50 values of 7.25 and 5.89 mg extract/ml, respectively. EC 50 values in reducing power were 1.12, 1.37, 2.48 and 1.41 mg extract/ml, whereas those in scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl radicals were 0.30, 0.40, 0.72 and 5.00 mg extract/ml for Ling chih, baby Ling chih, mycelia and filtrate, respectively. At 20 mg/ml, scavenging abilities on hydroxyl radicals were in the descending order of Ling chih>baby Ling chih>mycelia>filtrate. Total phenols were the major naturally occurring antioxidant components found in hot water extracts and in the range of 40.86–42.34 mg/g. From EC 50 values obtained, fruit bodies of G. tsugae (Ling chih and baby Ling chih) were good in antioxidant properties, except for the chelating ability on ferrous ions.
TL;DR: In this article, an aqueous coriander extract obtained through a sequential extraction process, was analyzed using chromatography and mass spectrometry in order to identify the phenolic compounds responsible for its antioxidant activity.
Abstract: An aqueous coriander extract obtained through a sequential extraction process, was analysed using chromatography and mass spectrometry in order to identify the phenolic compounds responsible for its antioxidant activity. Four fractions were identified from the crude extract using chromatography in a silica gel column. Their antioxidant activity, according to the β-carotene/linoleic acid model, was similar to one another but inferior to that of the crude extract and of butylated hydroxytoluene. Of the phenols identified through gas chromatography and mass spectrometry, it was noted that caffeic acid was present in high concentration (4.34 μg/ml in fraction I and 2.64 μg/ml in fraction III), whereas protocatechinic acid and glycitin were present in high concentration in fraction II (6.43 μg/ml) and fraction IV (3.27 μg/ml), respectively. These results, when considered with the recognized antioxidant ability of phenolic acids, suggest that they are principal components responsible for the antioxidant activity of the aqueous coriander extract.
TL;DR: In this article, the inhibitory effect of cell-free filtrates of Lactobacillus bulgaricus (6 strains), L. casei (4 strains, L. plantarum (2 strains), l. brevis (1 strain), lactic acidophilus, fermentum, and helveticus was determined against test bacteria (Staphylococcus aureus, Escherichia coli, Yersinia enterocolitica).
Abstract: Inhibitory effect of cell-free filtrates of Lactobacillus bulgaricus (6 strains), L. casei (4 strains), L. plantarum (2 strains), L. acidophilus (2 strains), L. brevis (2 strains), L. fermentum (1 strain), L. lactis (1 strain), and L. helveticus (1 strain) isolated from Turkish dairy products were determined against test bacteria (Staphylococcus aureus, Escherichia coli, Yersinia enterocolitica). All strains showed antimicrobial activity against test bacteria. Bacteriocin-like substances producing strains were determined under conditions eliminating the effects of organic acids and hydrogen peroxide. As a result, it was observed that inhibitory activities of three strains were due to bacteriocin-like substances. They were resistant to heat (100 °C for 10 and 20 min). The inhibitory activity of bacteriocin-like substances was not lost after 10 and 20 min at 100 °C. The inhibition observed in these studies could not have been due to the probable hydrogen peroxide production, since it was unaffected by catalase. The purified bacteriocin-like substances were identified as 29 kDa peptide by sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE). Molecular weights of bacteriocin-like substances were found the same in all three strains. This bacteriocin-like substances might be useful as a natural preservative.
TL;DR: In this paper, the flavour profile of juices made from fresh-cut pineapple fruits (n = 19 ; Costa Rica, Ghana, Honduras, Ivory Coast, Philippines, La Reunion, South Africa, Thailand) was studied in comparison to that of commercial water phases/recovery aromas (n. = 16 ), juice concentrates (N = 10 ) as well as commercially available juices (N. = 17 ).
Abstract: The flavour profile of juices made from fresh-cut pineapple fruits ( n = 19 ; Costa Rica, Ghana, Honduras, Ivory Coast, Philippines, La Reunion, South Africa, Thailand) was studied in comparison to that of commercial water phases/recovery aromas ( n = 16 ), juice concentrates ( n = 10 ) as well as commercially available juices ( n = 17 ). In addition, pineapple jams ( n = 6 ; market samples) were investigated. HRGC-MS analysis of juices made from fresh-cut fruit revealed the known prevalence of esters, with methyl 2-methylbutanoate, methyl 3-(methylthio)-propanoate, methyl butanoate, methyl hexanoate, ethyl hexanoate and ethyl 3-(methylthio)-propanoate, as well as 2,5-dimethyl-4-methoxy-3(2H)-furanone (mesifurane) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (furaneol) as major constituents. A corresponding flavour profile was rarely found in water phases/recovery aromas under study. In most cases, the characteristic methyl esters and hydroxy or acetoxy esters were lacking completely or appeared only in minor amounts in these products. Whereas a few of the commercial single strength juices revealed fruit-related flavour profiles, juices produced from concentrates mostly exhibited a flavour composition similar to that of concentrates, i.e. they were predominantly determined by their contents of furaneol and did not show the fruit-related ester distribution. Similarly, the jams under study were poor in typical pineapple constituents.
TL;DR: This article 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.
Abstract: 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.