Synbiotic functional drink from Jerusalem artichoke juice fermented by probiotic Lactobacillus plantarum PCS26.

A probiotic strain Lactobacillus plantarum PCS26 was used to ferment Jerusalem artichoke juice. Growth kinetics of the bacterial strain was followed during juice fermentation both in flask and in laboratory fermentor. Jerusalem artichoke showed to be an excellent source of nutrients for L. plantarum PCS26 growth. The culture grew very well reaching more than 10(10) cfu/ml in just 12 h. The pH changed from the initial 6.5 to 4.6 at the end of fermentation. The culture hydrolyzed fructooligosaccharides present in the Jerusalem artichoke juice, yielding fructose which was presumably consumed along with the malic acid as energy and carbon source. Lactic acid was the main metabolite produced in concentration of 4.6 g/L. Acetic and succinic acid were also identified. Sensory evaluation of the fermented Jerusalem artichoke juice and its mixtures with blueberry juice showed that the 50/50 % v/v mixture would be very well accepted by the consumers. Above 80 % of the panelists would buy this drink, and over 60 % were willing to pay more for it. Culture survivability in the fermented juices during storage at 4-7 °C was assayed by the Weibullian model. The product shelf-life was extended from 19.70 ± 0.50 days of pure Jerusalem artichoke juice to 35.7 ± 6.4 days of the mixture containing 30 % blueberry juice.

Application of ultrasound for enhanced extraction of prebiotic oligosaccharides from selected fruits and vegetables.

Ultrasound assisted extraction (UAE) was used to extract oligosaccharides from selected fruits (blueberry, nectarine, raspberry, watermelon) and vegetables (garlic, Jerusalem artichoke, leek, scallion, spring garlic and white onion). The individual fractions of the oligosaccharides were analyzed: 1-kestose (GF2), nystose (GF3) and 1F-ß-fructofuranosylnystose (GF4) from the fructo-oligosaccharides (FOS), and raffinose and stachyose from the raffinose family oligosaccharides (RFO). Extraction parameters including solvent concentration (35-85% v/v), extraction temperature (25-50°C) and sonication time (5-15min) were examined using response surface methodology (RSM). Ethanol concentration of 63% v/v, temperature of 40°C and extraction time of 10min gave maximal concentration of the extracted oligosaccharides. The experimental values under optimal conditions were consistent with the predicted values. UAE increased the concentration of extracted oligosaccharides in all fruits and vegetables from 2 to 4-fold compared to conventional extraction. The highest increase of total oligosaccharides extracted by UAE was detected in Jerusalem artichoke, 7.17±0.348g/100gFW, compared to 1.62±0.094g/100gFW with conventional method.

Characterization of multilayered and composite edible films from chitosan and beeswax.

Chitosan-based edible films were prepared and subjected to cross-linking reactions using sodium tripolyphosphate and/or to beeswax coating on both films interfaces. In addition, chitosan-beeswax emulsion-based films were produced. The goal of these modifications of the chitosan films was the improvement of their barrier to water vapor and to decrease their affinity to liquid water maintaining or improving the mechanical and optical properties of the original chitosan films. The cross-linking with tripolyphosphate decreased both the water vapor permeability and the water absorption capacity to about 55% and 50% of that of the original chitosan films, respectively. However, there was an increase in the films stiffness, revealed by the increased Young modulus from 42 kPa up to 336 kPa. The multilayered wax-chitosan-wax films exhibited a similar improvement of the barrier properties to water vapor, with the advantage of maintaining the mechanical properties of the original chitosan films. However, these wax-coated films showed a higher water absorption capacity, which is believed to be a consequence of water entry into small pores between the film and the wax layers. Regarding the film samples subjected to cross-linking and further coating with beeswax, a similar behavior as the uncoated cross-linked films was observed. The emulsion-based composite films were characterized by a substantial decrease of the water vapor permeability (40%), along with a decrease in their stiffness. Regarding the optical properties, all films presented a yellowish color with similar values of lightness, chroma, and hue.

Physical and sensory properties of ready to eat apple chips produced by osmo-convective drying.

The low cost raw material, apple variety Idared, was turned into value-added product, apple chips. The apple chips were produced in a two-step process consisting of osmotic treatment and conventional drying. Osmotic treatment was carried out in 40 % glucose solution at room temperature, followed by convective drying at 105 °C, till reaching water activity of 0.3. Mechanical properties of the apple chips measured by compression and penetration tests were correlated with the sorption properties. The low browning index, 25.5 and high whitening index, 63.7, proved the good retention of the color of the apple chips. The instrumental characteristics of the apple chips were correlated with the sensory characteristics of the product. The new product was accepted by the 95 % of the panelists. The stored apple chips under modified atmosphere showed no significant changes in the quality parameters over 6 month period.

Galacto-oligosaccharides synthesis from lactose and whey by ß-galactosidase immobilized in PVA.

The synthesis of galacto-oligosaccharides (GOS) by ß-galactosidase immobilized in both polyvinyl alcohol (PVA) lenses and sol-gel carriers was studied and compared with the performance of the free enzyme. PVA-immobilized ß-galactosidase retained 95 % of the initial activity after seven repeated uses and retained 51 % of the initial activity after 3 months of storage, while sol-gel-immobilized ß-galactosidase only retained 39 % of the initial activity under storage. Lactose conversion takes place at a higher rate in the PVA-immobilized ß-galactosidase, while the lowest rate of lactose conversion was noticed with immobilized ß-galactosidase in sol-gel. Continuous production of GOS from either lactose or whey, with PVA-immobilized ß-galactosidase, was performed in a packed-bed reactor. A maximum GOS production of 30 % of total sugars was attained for a 40-% lactose feed solution with a feed rate of 10.8 ml/h, at pH 4.5 and 40 °C, corresponding to a productivity of 117 g/l h. The maximum GOS productivity of 344 g/l h was obtained at a flow rate of 28.7 ml/h. 3-OS and 4-OS were the major types of GOS formed. Conversion of whey in continuous mode resulted in GOS production of 15 % of total sugars and formation of 45 % 3-OS, 40 % 4-OS, and 15 % 5-OS.

Ethanol production using immobilized Saccharomyces cerevisiae in lyophilized cellulose gel.

A new lyophilization technique was used for immobilization of Saccharomyces cerevisiae cells in hydroxyethylcellulose (HEC) gels. The suitability of the lyophilized HEC gels to serve as immobilization matrices for the yeast cells was assessed by calculating the immobilization efficiency and the cell retention in three consecutive batches, each in duration of 72 h. Throughout the repeated batch fermentation, the immobilization efficiency was almost constant with an average value of 0.92 (12-216 h). The maximum value of cell retention was 0.24 g immobilized cells/g gel. Both parameters indicated that lyophilized gels are stable and capable of retaining the immobilized yeast cells. Showing the yeast cells propagation within the polymeric matrix, the scanning electron microscope images also confirmed that the lyophilization technique for immobilization of S. cerevisiae cells in the HEC gels was successful. The activity of the immobilized yeast cells was demonstrated by their capacity to convert glucose to ethanol. Ethanol yield of 0.40, 0.43 and 0.30 g ethanol/g glucose corresponding to 79%, 84% and 60% of the theoretical yield was attained in the first, second and third batches, respectively. The cell leakage was less than 10% of the average concentration of the immobilized cells.