Effect of Superchilling (Hyo-On) Aging on the Total Bacterial Count and Concentration of Taste Components of Pork Loin

氷温を利用した肉類の長期熟成処理の有用性を評価するために、従来の熟成処理温度である4℃および氷温である−1℃で豚ロース肉の熟成処理を行い、一般生菌数、イノシン酸および遊離アミノ酸濃度に及ぼす影響を評価した。−1℃熟成処理の一般生菌数は、4℃熟成処理と比較して、熟成処理7、14および21日で有意に低下した。さらに−1℃熟成処理42日後でも、肉類が腐敗したと判断する一般生菌数である108コロニー形成単位/gには達していなかった。一方、−1℃熟成処理のイノシン酸濃度は、4℃熟成処理と比較して、緩やかな減少がみられた。腐敗の指標の1 つである一般生菌数が同等であった4℃熟成処理14日および−1℃熟成処理42日について遊離アミノ酸濃度の測定および官能評価を実施した。その結果、豚ロース肉の−1℃熟成処理42日は、4℃熟成処理14日と比較して、うま味に関わるグルタミン酸濃度の有意な上昇と嗜好型官能評価において総合的に好ましいと評価された。これらの結果より豚ロース肉の−1℃熟成処理は、4℃熟成処理よりも、一般生菌数の増殖抑制と食味性を向上させることで付加価値の向上に寄与できると考えられる。To evaluate the effects of long-term meat aging at superchilling, the total bacterial count, concentration of taste components, and palatability of pork loin were compared for samples aged at 4 °C and −1 °C. At 7, 14, and 21 days of aging, the total bacterial count of pork aged at −1℃ had significantly decreased compared to that of the sample aged at 4 ℃. Even after aging pork at −1 °C for 42 days, the total bacterial count did not reach 108 colony forming unit/g, which is generally considered to be the spoilage of meat. The concentration of inosinic acid in the pork loin aged at −1 ℃ was s decreased more slowly than that of the sample aged at 4 ℃. Free amino acid analysis and sensory evaluation were performed on the samples aged at 4 °C for 14 days and at −1 ℃ for 42 days, in which the total bacterial count was almost equivalent. Further, the glutamic acid concentration and overall palatability of pork loin sample aged at −1 ℃ for 42 days were significantly increased as compared to those of samples aged at 4 °C for 14 days. From these results, it was concluded that aging at −1 ℃ increased the added value of pork by suppressing the growth of bacteria and improving its palatability over that achieved from samples aged at 4 °C.本研究の一部は、2020年度関西大学若手研究者育成経費（個人研究）において、研究課題「熱成処理温度の違いが食肉の呈味成分の生成に関与するアミノペプチダーゼ活性に及ぼす影響」として研究費を受け、その成果を公表するものである

Correlative Analysis of Ion Concentration Profile and Surface Nanoscale Topography Changes using Operando Scanning Ion Conductance Microscopy

Although various spectroscopic methods have been developed to capture the ion concentration profile changes, it is still difficult to visualize the ion concentration profile and surface topographical changes simultaneously during the charging/discharging of LIBs. To tackle this issue, we have developed an operando scanning ion-conductance microscopy (SICM) method that can directly visualize an ion concentration profile and surface topography using a SICM nanopipette whilst controlling sample potential or current by potentiostat for characterizing the polarization state during charging/discharging. Using operando SICM on the negative electrode (anode) of LIBs, we have characterized ion concentration profile changes and the reversible volume changes related to the phase transition during cyclic voltammetry (CV) and charge/discharge of the hard carbon anode. Operando SICM is a versatile technique that is likely to be of major value for evaluating correlation of the electrolyte concentration profile and nanoscale surface topography changes