Modification of media using food-grade components for the fermentation of Bifidobacterium and Lactobacillus strains in large-scale bioreactors.

Probiotic bacteria continue to receive increasing attention in the food and feed industries. However, the production of Bifidobacterium and Lactobacillus at an industrial scale is challenging because of specific nutrient requirements and conditions, which are complicated and costly. We developed low-cost culture media by modifying the carbon and nitrogen sources for Bifidobacterium animalis subsp. lactis KMP-H9-01 and Lactobacillus reuteri KMP-P4-S03 from available food grade components. Sucrose (15 g/l) was selected as a suitable carbon source for both strains because it was the most economic and facilitated bacterial growth that was equal to that of glucose. The Bifidobacterium strain required beef extract as a nitrogen source to multiply. The fermentation of both strains using the modified media formula in 5-L and 50-L bioreactors showed that the highest cell counts of L. reuteri and B. animalis subsp. lactis were 9 and 9.8 log CFU/ml after 12-15 h, respectively. The concentration (g/l) ratio between lactate and acetate obtained from B. animalis subsp. lactis was 7:7.4 at 12 h and 11.4:10.6 at 40 h; the ratio was similar at both time points (6.9: 1.1) for L. reuteri. Thus, this economically modified food-grade medium for the large-scale fermentation of two probiotic bacteria was efficient.

Stand-Alone Semi-Solid-State Electrochemical Systems Based on Bicontinuous Microemulsion Gel Films.

Bicontinuous microemulsion (BME)-based hydrogel films were integrated with screen-printed electrodes (SPEs) comprising working, counter, and reference electrodes to form stand-alone, semi-solid-state electrochemical systems that do not require an outer electrolyte solution. The gel network of the BME hydrogel only exists in the microaqueous phase and retains the structure of the entire BME gel. Following gelation, a microaqueous phase with sufficient ionic strength ensured effective ionic conductivity, even in thin gel films. This enabled the electrochemical reaction to proceed using a thin gel film as an electrolyte solution. However, an intact micro-oil phase with no gel network enabled efficient extraction from an external oil solution and exhibited rapid electrochemistry that was comparable to that of a BME solution. Cyclic voltammograms of lipophilic redox species in oil using the gel-integrated SPE system demonstrated successfully in the oil itself and in the air with dropped oil onto the system.

Underwater Shockwave Pretreatment Process to Improve the Scent of Extracted Citrus junos Tanaka (Yuzu) Juice.

Citrus junos Tanaka (yuzu) has a strong characteristic aroma and thus its juice is used in various Japanese foods. Herein, we evaluate the volatile compounds in yuzu juice to investigate whether underwater shockwave pretreatment affects its scent. A shockwave pretreatment at increased discharge and energy of 3.5 kV and 4.9 kJ, respectively, increased the content of aroma-active compounds. Moreover, the underwater shockwave pretreatment afforded an approximate tenfold increase in the scent intensity of yuzu juice cultivated in Rikuzentakata. The proposed treatment method exhibited reliable and good performance for the extraction of volatile and aroma-active compounds from the yuzu fruit. The broad applicability and high reliability of this technique for improving the scent of yuzu fruit juice were demonstrated, confirming its potential for application to a wide range of food extraction processes.

Improving the antioxidant functionality of Citrus junos Tanaka (yuzu) fruit juice by underwater shockwave pretreatment.

Citrus junos Tanaka (yuzu) has a strong characteristic aroma, and hence, yuzu juice is used in a number of Japanese foods. We herein evaluated the functional compounds of yuzu juice to investigate whether underwater shockwave pretreatment affects its functionality. Employing the shockwave pretreatment at an increased discharge and energy of 3.5kV and 4.9kJ, respectively, resulted in an increase in the flavanone glycoside content and oxygen radical absorbance capacity (ORAC). The ORAC value of yuzu juice cultivated in Rikuzentakata increased approximately 1.7 times upon underwater shockwave pretreatment. The treatment method proposed herein exhibited reliable and good performance for the extraction of functional and antioxidant chemicals in yuzu fruits, and was comparable with traditional squeezing methods. The high applicability and reliability of this technique for improving the antioxidant functionality of yuzu fruit juice was demonstrated, confirming the potential for application to a wide range of food extraction processes.

Direct Analysis of Lipophilic Antioxidants of Olive Oils Using Bicontinuous Microemulsions.

Quantitative analyses of olive oil for lipophilic antioxidants, such as α-tocopherol and phenolics, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), which was bicontinuously composed of saline and toluene microphases with a surfactant system. Lipophilic antioxidants in oils were directly monitored in BME solutions using a lipophilic, fluorinated nanocarbon-film electrode (F-ECR). The combination of a well-balanced BME and extremely biased electrodes, such as strongly hydrophilic indium/tin oxide and strongly lipophilic (hydrophobic) F-ECR, allowed individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without any required extraction. Furthermore, values for the charge Q, integrated from observed currents, showed good linear relationships with the results of conventional assays for antioxidant activity, namely, total phenolics and oxygen radical absorbance capacity assays, even with practical food samples. This proposed methodology provided a very simple, rapid, easily serviceable, and highly reproducible analysis that possesses great potential for applications to a wide range of chemical mixtures, in terms of analyte and media, beyond food oils.

Simultaneous electrochemical analysis of hydrophilic and lipophilic antioxidants in bicontinuous microemulsion.

Qualitative and quantitative analyses of hydrophilic and lipophilic antioxidants, such as polyphenols, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), in which water and oil phases coexisted bicontinuously on a microscopic scale. Hydrophilic and lipophilic antioxidants were individually monitored in the same BME solution using a hydrophilic indium tin oxide (ITO) electrode and a lipophilic fluorinated nanocarbon film electrode (F-ECR), respectively. The combination of well-balanced BME and extremely biased electrodes, such as ITO and F-ECR, in terms of hydrophilic-lipophilic balance allowed us to achieve individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without extraction. Furthermore, the antioxidant activities of functional liquid foods, such as coffee and olive oil, were also evaluated by means of electrochemical measurements in BME solutions containing analytes in concentrations of several percent. The technique we propose provides a very simple, rapid, easily serviceable, and highly reproducible analysis and can be extended to a wide range of analytes and media.