食品の物性解析およびプロセス開発に関する工学的研究 <解説(2006年度日本食品工学会賞)>

A novel method to measure viscosity and static shear modulus of viscoelastic food fluids was developed. This method is based on the flow theory of fluid and shear deformation of elastic material in an annular channel. The method, the non-rotational concentric cylinder method, evaluated static viscoelasticity of sample in a cup easily by analyzing the force acting on a plunger immersed in the sample during the period of time of the cup movement for a very short distance at a constant speed to the axial direction. Dependence of apparent viscosity on shear rate is also evaluated by this method. A new emulsification method called the membrane emulsification method combined with preliminary emulsification was developed. The method prepares mono-dispersed and stable O/W or W/O emulsions easily at a high rate. Mean particle diameters prepared by this method were about two times larger than the mean pore size of the membrane used. The mean particle diameter decreased and mono-dispersibility increased with the increase of permeating flux (or pressure) of pre-emulsified emulsion. Stable and fine particle (ca. 3 μm) multi-phase emulsions such as W/O/W and O/W/O types could be prepared by using this method. The membrane phase inversion emulsification method was also developed by applying the membrane emulsification method combined with preliminary emulsification. This method prepared mono-dispersed and stable O/W or W/O emulsions with very high dispersed phase concentration up to about 80% or more. Characteristics of a newly developed superheated steam (SHS) treatment combined with far infrared heating (FIH) were investigated. Heat transfer rate under steady state condition could be estimated from empirical equations for convective and radiative heat transfer from the SHS and radiative heat transfer from the FIH heater and chamber wall. Very few degradation of edible oil was found in the SHS treatment because of almost no oxygen in the SHS. Carbonization rate of biomaterials treated in the SHS was expressed by the first ord非ニュートン流動性に加えて粘弾性を示す液状食品の粘度と弾性率を同時に測定する新規な静的粘弾性測定を開発した. この方法は, 流体の環状路での流動理論と弾性体のずり変形理論に基礎をおき, 同心二重円筒からなる測定部の外筒(カップ)を定速で軸方向に微小距離移動させる際に, 試料が内筒(プランジャー)に与える荷重を測定して静的粘弾性を解析するもので, 非回転二重円筒法とよぶ. 液状試料の粘度とずり弾性率を, 短時間で精度よく測定でき, 見かけ粘度のずり速度依存性などの非ニュートン流動性も評価できる. 単分散性と安定性の高いO/WまたはW/Oエマルションを生産性よく調製できる予備乳化を伴う膜乳化法を開発した. この方法で調製されるエマルションの平均粒径は, 使用する多孔質膜の平均細孔径の約2倍であり, 予備乳化エマルションの膜透過速度(または圧力)の増加により平均粒径は減少し, 単分散も向上する. 予備乳化を伴う膜乳化法の応用技術として, 転相膜乳化法を開発した. この方法では, 予備乳化の容易な低濃度エマルションを転相させることで, 分散相濃度が80%以上の高濃度のO/W又はW/Oエマルションを調製することができる. また, 予備乳化を伴う膜乳化法を用いれば, 3μm程度の微小粒径で単分散性の高いW/O/Wエマルション等の多相エマルションも調製できる, 遠赤外線などの併用による新規な過熱水蒸気処理法を開発し, その処理特性を検討した. この方法は, 省エネルギ性と操作性が高く, 定常状態での伝熱速度は, 過熱水蒸気による対流伝熱と放射伝熱, 遠赤外線ヒータおよび装置内壁からの放射伝熱を考慮して推定可能であることを明らかとした. 無酸素加熱が可能な過熱水蒸気処理では食用油の劣化は極めて少ないことを明らかとした. また, 過熱水蒸気処理による植物系試料の炭化速度は1次反応速度式で表され, 温度が高く試料サイズが小さくなるほど炭化速度が高くなること, および遠赤外線加熱の併用で, 炭化エネルギが大幅に低減できることを明らかとした