奈米化珍珠粉之理化特性與生體可用率

Abstract

珍珠為天然軟體動物體內分泌之珍珠質，經2-5年累積於體內所形成，將珍珠研磨成細粉即為珍珠粉，為中國人傳統之名貴中藥，並已使用超過一千年，目前國內以食品管理。奈米科技為近年來重要之科技發展之一，奈米科技亦漸漸應用於食品、藥品與生物科技之發展上，因許多物質在奈米化後，其特性將可能改變。本研究以新型之乾式低溫奈米研粉系統，將淡水養殖之三角帆蚌珍珠研磨成奈米珍珠粉與微米珍珠粉，並利用物理、化學或生物方法探討珍珠粉之製備、粒徑、營養成分、生理安全性、熱特性、顏色變化、晶相、微觀特性、生體可用率等。 結果顯示，使用乾式低溫奈米研粉系統確實可製備奈米珍珠粉，證明物理研粉法可將珍珠粉奈米化，且粉碎比可達186,170，其粒徑分佈相當集中。淡水養殖三角帆蚌珍珠之鈣含量約36.05%，粗蛋白約2.1%~2.0%，碳水化合物約1.0%~1.1%，粗脂肪約0.1%。而微量元素或微量元素之化合物總量約為6.05%。矽、硫、磷亦為珍珠粉之成分。砷、鉛、鎘、汞等四種重金屬並未檢出，表示安全性可以預期，養殖水質符合標準。由熱重動力學參數，發現200℃前之失重應為水分含量，第一階段熱裂解約在224~500℃，為粗蛋白、碳水化合物、粗脂質之總量，約為4.2%，第二階段熱裂解約在500~770℃，主要為二氧化碳之散失與少量硫、磷之含量，依此推算碳酸鈣之含量約為90.0%。 珍珠研磨後，其粉紅色光澤均消失變成白色，紅色消失應為紅色物質被破壞，顏色變白可能為珍珠表面粗糙使入射光散射所造成。研粉過程中輕微綠色物質釋出，黃色物質破壞。分析XRD繞射峰強度，發現在微米化過程中可能影響晶系穩定性，在奈米化後顆粒內應力才消失。繞射峰無寬化效應，其晶粒大小應大於0.1 μm。由電子顯微鏡與粒徑分佈分析發現奈米化珍珠粉有團聚現象，故建議珍珠粉之粒徑檢測應同時考慮使用雷射粒徑分析儀分析並配合穿透式電子顯微鏡以確認。 藉由臨床認定的健康受試者，使其攝取含780 mg鈣質之奈米與微米珍珠粉，發現奈米珍珠粉攝取後，由血清總鈣質的增加、尿液總鈣/肌酸酐的增加、血清副甲狀腺素的降低與相關生體可用率等指標，發現奈米珍珠粉的生體可用率應優於微米珍珠粉。

Pearl is a natural product from 2-5 years old mollusks. Pearl powder, prepared from milling, has been a valuable medicine to Chinese people for more than 1000 years. It is regarded as a food supplement in Taiwan. Nanotechnology is a new technology in many industries including food, pharmacy and biotechnology. The characteristics of materials change in nanonization. In the present study, cultivated fresh water pearl millet (Hyriopsis cumingii Lea) over 3 years old was ground to nanonized pearl powder (NPP) and micronized pearl powder (MPP) using a novel dry cryo-nanonization grinding system. The particle size distribution, composition, safety, thermal characteristics, color change, crystallinity, microcosmic characteristics, and bioavailability of pearl powder were investigated by physical, chemistry, and biological methods. Results show that the size reduction ratio reached 186,170 and that the particle size distribution of the nanonized pearl powder was centralized by the novel dry cryo-nanonization grinding system. The cultivated fresh water pearl contains about 36.05% calcium, 2.0 ~ 2.1% crude protein, 1.0 ~ 1.1% carbohydrate, and 0.1% crude fat. The total trace elements and their derivates were about 6.05%. Silicon, sulfur, and phosphorous were present. No residual heavy metals including arsenic, lead, cadmium and mercury were detected, supporting the safety of these pearl powders as a food supplement. In thermal gravimetric analysis indicated that water loss occurred before reaching 200 0C, that the weight loss caused by thermal decomposition of crude protein, carbohydrate and crude fat occurred in stage 1 around 224~500℃ was 4.2% in total, and the weight loss caused by the dissipation of carbon dioxide mainly plus the burning of trace sulfur or phosphorous occurred in stage 2 around 500 ~770℃. The data in stage 2 corresponds to approximately 90.0% content of calcium carbonate in pearl. The lustrous pink color disappeared and white color appeared in grinding pearl, presumably resulted from the destruction of outer layer. Light green tint showed up and yellow tint reduced as well. The XRD spectra showed that the crystallinity stability is affected during micronization, while the inner strain in pearl powder is reduced after nanonization. The absorption peak didn’t spread wide, indicating that the crystallite size should be over 0.1 μm. TEM and particle size analyses confirmed the agglomeration in NPP. It is suggested to use laser particle size analyzer coupled with TEM analysis for sizing NPP. Either NPP or MPP containing 780 mg calcium was orally administered to each healthy adult in clinical trials. The serum total calcium increment, the serum intact parathyroid hormone reduction, and the urine calcium/creatinine ratio increment and bioavailability indexes showed that better bioavailability of NPP than MPP.