Freezing wheat dough has great benefits in reducing baking costs and time, but bread baked from frozen dough has a smaller loaf, coarser crumb, and harder crust than bread baked from fresh dough. In addition to the preservation process, the ingredients added to frozen dough have a substantial positive impact on the quality of frozen dough. In this study, the effects of the addition of oil on the physical properties of frozen dough and the quality of the bread baked after freezing and thawing were examined. Quality change was investigated for four types of frozen dough made from four different fats with different triacylglycerol constituent fatty acids. Frozen dough with added soybean oil and grapeseed oil had a thicker crumb skeleton after baking. In addition, the frozen dough with soybean oil showed less stretchiness and more protein conglutination. The ratio of unsaturated fatty acids in the oil tended to adjust the extensibility of the frozen dough and alter the crumb skeleton of the baked bread.

The primary physicochemical aspects of freezing are the substantial reduction of water activity and the increase of osmotic pressure by freeze-induced concentration. The temperature-dependent ice fraction subsequently affects the changes in thermal properties and specific chemical reaction processes. In frozen food, the ice structure is strongly determined by the moving ice-front through the balance of water mass transfer and heat transfer. By controlling the ice structure, progressive freeze-concentration could be applied to concentrate liquid food with high quality. In some living organisms, freeze-related biosubstances are produced and accumulated for freeze-tolerance. The cell structure also plays an important role in the freeze-tolerance of cells in microorganisms, plants, and animals.

多くの固体食品は非晶質であり，その物理的性質はガラス-ラバー転移温度（T_g）を境に大きく変化する．食品のT_g は水分含量の増加と共に低下する（水の可塑効果）．T_g が環境温度よりも低下したとき，一定温度であってもガラス転移は起こる．T_g が25°Cになるときの水分含量は一般にクリティカル水分含量（w_c）と呼ばれる．本総説では，ガラス-ラバー転移がクッキーの食感，マンゴー粉末の固着，スープ粉末の圧縮成型性に及ぼす影響について紹介する．これら食品のT_g は示差走査熱量計，或は昇温レオロジー測定によって評価され，T_g と水分含量との関係からw_c が決定される．クッキーの破断特性はw_c を境に脆性から延性へと変化した．マンゴー粉末は水分含量がw_c 以上になったとき，著しく固着した．圧縮成形したスープ固体の硬さは，T_g 以上の温度で圧縮することで硬くなった．

Water often controls the processability and preservability of foods, especially those of the low-water content, by means of mobilities of water and food polymer molecules. Glass transition is a concept of dynamics governs the mobilities and physical properties of foods as well. An explanatory address with a focus on the glass transition in foods was then presented in this workshop.

断熱型熱量計を用いて熱容量とエンタルピー緩和速度を測定することにより，1）シリカMCM-41，2）デキストランゲルsephadex G10，3）水溶性牛血清アルブミン（BSA）それぞれの細孔水の熱挙動を50〜300Kの温度範囲で調べた．3つの細孔壁は，親水性/疎水性，細孔形状，形状柔軟性等において異なる．MCM-41には細孔直径1.5〜5.0nmを用い，過剰量の水を添加した．G10とBSAの測定には，それぞれ水分量（無水物に対する水の質量比）h=0.273と0.321を用いた．MCM-41細孔水は直径2.1nm以下で115，165，210Kの複数の温度付近でガラス転移を示した．115Kは細孔壁に接した界面水分子に因る．後者2つは内部水に因り，細孔径の増大とともに転移温度は階段的に上昇した．各ガラス転移は低温からそれぞれ，配置変化が2，3，4本の水素結合を切断して進行する過程に対応するものと解釈した．G10細孔水が273K付近で取り得る配置の数はバルク水，さらにはMCM-41細孔水に比較しても少ない．室温付近ではゲル高分子自身の配置変化も進行しながら，細孔水に可能な配置数が増大している．BSA細孔水が取り得る配置の数は，室温でも少なく，h=0.321ではBSAの高次構造がBSA分子内の相互作用で決まり，非晶性細孔水は狭い隙間にあることを示唆する．

Bioencapsulation of food additives or functional ingredients aims to protect sensitive core materials during storage and consumption, transport them to designated positions in the gastrointestinal tract, and release them at appropriate rates to maximize bioavailability. Bioencapsulation systems need to be designed with GRAS (generally recognized as safe) materials, and the physicochemical processes involved in matrix formation are crucial for realizing expected functionality. From an engineering perspective, it is important to develop a processing method for obtaining products with desirable features. The author has previously reported that a freezing step represents an interesting processing tool for controlling the properties of an encapsulation system. During freezing, the growth of ice crystals in an aqueous solution results in a cryoconcentrated (freeze-concentrated) phase that is controlled by phase equilibrium. The author’s idea is to control matrix formation in the cryoconcentrated phase for optimizing encapsulation systems. This review summarizes this concept and future scope.

Microencapsulation of flavor is an important technology whereby liquid flavor is enclosed in a carrier matrix by spray drying. In this review, the flavor release from spray-dried powder is discussed. Flavor release from the spray-dried powder could be correlated using the Avrami (Weibull) equation. In the analysis of flavor release from the powder, the unknown parameters were: the diffusion coefficient of flavor in the matrix, D_out, diffusion coefficient of flavor in the flavor droplet, D_in, and mass transfer coefficient from the powder, κ_L, which were estimated to fit d-limonene release behavior by using the partial differential equation model. First, the parameters were determined by fitting with the experimental database, assuming that the release in the matrix was the rate limiting step (D_in»D_out). The diffusion model could explain well the release characteristics of encapsulated d-limonene. For the release of encapsulated d-limonene from the spray-dried powder at 51% RH and 50°C, diffusion of flavor inside the matrix was the rate-limiting step. The encapsulated flavor powder with vacuoles showed greater release than powder without vacuole formation.

The quality control of frying oil and the management of cooking processes are critical to the taste of fried foods, and to the safety and economic efficiency of the commercial production of fried foods. The authors conducted research to assess the degradation of frying oil by studying its electrical properties and observed peculiar behavior of the dielectric constant believed to be caused by water present in the frying oil. An analysis of the dielectric constant suggested that water remains in high-temperature frying oil for a relatively long period of time. It is generally thought that water promptly reaches its boiling point of 100°C when added to high-temperature frying oil and is immediately discharged from the oil and into the atmosphere as steam. Verification that water indeed remains in frying oil at elevated temperature for long periods of time would indicate that there is a mechanism that hinders the discharge of water from high-temperature oil. Accordingly, in this paper we reproduce the conditions in which water remains in the frying oil and consider the factors causing this retention. We also discuss methods for extending the life of frying oils by controlling and managing the degradation of oil caused by hydrolysis when used frying oil is stored.