Quality Evaluation of Drinks Based on Liposome Shape Changes Induced by Flavor Molecules

Assessment of beverage quality for ethyl caproate and procyanidin B2 utilizing binary liposomes

Procyanidins are bioactive compounds present in fruits like apples. These compounds can be extracted and studied for their functional properties. Within the class of procyanidins, procyanidin B2 (PB2) serves as a standard reference. Sake, a traditional Japanese alcoholic beverage, contains ethyl caproate (EC), which adds economic value to the drink. Analyzing PB2 in apple juice and EC in sake, particularly in simple prepared beverages without the use of organic solvents or in their original state, requires the application of binary liposomes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). In this study, I investigated the size of liposomes and the ratio of solid ordered (So) to liquid disordered (Ld) liposomes. The results indicated that PB2 increased the size of liposomes, while EC decreased it. Additionally, EC influenced the ratio of So/Ld liposomes. These findings provide a foundational understanding for further research on the biophysical and physiological properties of EC and PB2.

Materials evaluation using cell-sized liposomes

Cell membranes play a vital role in delineating the internal cellular environment from the external surroundings, going beyond mere compartmentalization. Researchers have delved into the structural organization, properties, and functional roles of biological membranes, paving the way for their application in substance identification, detection, and quantification. This review introduces various studies and their implications for future research. It underscores the advantages of employing cell-sized liposomes, which enable real-time observation for rapid detection and analysis of diverse materials. The utility of cell-sized liposomes extends to their size, dynamic shape changes, and phase-separation, offering valuable insights into the evaluation of targeted materials.

Phase-Separated Structures of Sake Flavors-Containing Cell Model Membranes

Sake (a traditional Japanese alcoholic beverage) contains ethyl caproate (EC), which enhances its economic value. Isovaleraldehyde (IVA) is also a well-known flavoring agent in alcoholic beverages, which some people enjoy. Recently, studies revealed that EC decreased the size of homogenous 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes whereas IVA increased their size. Cholesterol (Chol) and ergosterol were previously referred to as animal and fungus sterols. For the first time, this study demonstrated the phase behavior of the membrane in cell-sized liposomes containing EC and IVA. After adding EC, the solid ordered/liquid disordered (Ld) and liquid ordered (Lo)/Ld phase separation in DOPC/dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol or ergosterol ternary membranes decreased, but the Lo/Ld phase separation decreased after adding IVA. Biophysics, physiological, and application aspects of EC and IVA evaluation were discussed. The findings of this study not only enhance our understanding of the function of flavors but also provide rapid and cost effective performance for the measurement.

Measurement and Characterization of Yeast Cell Size Using a Digital Optical Microscope

Yeast produces flavor components as by-products of fermentation. Such components, which account for considerable yeast quality value, may influence cell membrane fluidity and regulate cell size. In this study, yeast cell size was measured using various methods, and cell sizes were characterized for each strain of yeast. Herein, a method for measuring the cell size and automatically acquiring the cell area was proposed using inexpensive methylene blue staining and a versatile digital microscope to automatically acquire the cell area. To evaluate the efficiency, data on cell length and area were compared using the conventional and proposed methods. Additionally, the advantages of automated measurement and the ability to count cell numbers in the future are discussed through the acquisition of cell size data, which would be required for microfabrication and cell fabrication techniques. Although there are various candidate methods for evaluating the properties of each yeast strain, the present technique may be useful for evaluating the productivity of flavor components and selecting a yeast strain for producing food and drink products with high commodity values.

Charged Lipids Influence Phase Separation in Cell-Sized Liposomes Containing Cholesterol or Ergosterol

Positively charged ion species and charged lipids play specific roles in biochemical processes, especially those involving cell membranes. The cell membrane and phase separation domains are attractive research targets to study signal transduction. The phase separation structure and functions of cell-sized liposomes containing charged lipids and cholesterol have been investigated earlier, and the domain structure has also been studied in a membrane model, containing the yeast sterol ergosterol. The present study investigates phase-separated domain structure alterations in membranes containing charged lipids when cholesterol is substituted with ergosterol. This study finds that ergosterol increases the homogeneity of membranes containing charged lipids. Cholesterol-containing membranes are more sensitive to a charged state, and ergosterol-containing liposomes show lower responses to charged lipids. These findings may improve our understanding of the differences in both yeast and mammalian cells, as well as the interactions of proteins with lipids during signal transduction.