本研究選擇淡水吳郭魚進行4℃及20℃貯藏中肉質及生理變化測試和比較。以新設計一套肉質指標包括測試肌肉穿破力(penetration force; PF)、保水力(water holding capacity; WHC)和IMP含量來分別量化的代表嚼感(chewibility)、多汁性(juiciness)及肉質甜度(meaty sweetness; umami)，進行綜合肉質評估。實驗結果發現儲藏中肉質變化是受僵直作用、嫩化作用及腐敗作用互相競爭所造成複合性影響，而傳統K值僅能反映僵直作用進行程度，未能綜和呈現生理作用影響。穿破力曲線均會出現四階段的肉質嚼感變化，被證實與死後生理作用有關，此外穿破力曲線又可被用來鑑試出儲藏中肉質兩階段嚼感，初期的硬實期及後期的軟化期。並發現吳郭魚20℃及4℃儲藏中，臨界的嚼感維持期爲10及20小時；另保水力和IMP含量被證實均與僵直進程相關，愈新鮮未僵直魚肉的保水力和多汁性愈好。由IMP含量證實吳郭魚在其硬實期維持期的後半期會出現較高的累積，來反映有較佳的鮮甜口感的發生時期。
Changes of raw meat qualities of fresh water tilapia during postmortem storage at 4℃ and 20℃ were studied and compared. To improve the effectiveness, A set of new indices, including penetration force (PF), water holding capacity (WHC) and inosine monophosphate (IMP) content were to reflect chewibility, juiciness, and meaty sweetness for the evaluation of meat quality.
Experiment resource indicated raw meat qualities were affected by the competitional occurrences of rigor mortis, postmortem tenderization, and micrological spoilage. In sufficient to include the tenderization effect, K value was a index only capable to reflect the extent of rigor mortis development. Penetration force profiles of tilapia showed a four stage meat texture changes effected by physiochemical changes. In addition, to chewibility phase, a firmness period and losing period were easily found from each penetration force profile. Those the proper storage periods at specified temperate of a fish could be identified, ten and twenty hours for tilapia were determined to be the critical postmortem storage periods at 20℃ and 4℃..WHC and IMP content were evidenced to be affected only by the progress of rigor mortis. The less of rigor development, the higher the WHC, higher juiciness could be found in the earlier stage of postmortem storage. On contrary, higher IMP contents or meaty sweetness were found to occur at some what late stage of firmness retention period in the case of tilapia.
