臺灣博碩士論文加值系統

維生素A缺乏症是許多開發中國家在地方上普遍嚴重的健康問題，尤其是在非洲其更會增加五歲以下幼兒的致死率。在減緩這些問題的方法中，以食品為基礎的模式被認為是比較接近能維持攝取量的方式。
植物是維生素A的重要來源，胡蘿蔔素在開發中國家是對於貧窮是最易得到的營養源，而且可以達到相當於維生素A 80%營養需求量。然而，這些植物在發展中國家大多數具有季節性的出現。並且胡蘿蔔素對光、熱和氧氣非常敏感容易受到破壞。
本研究主要是開發甘薯的加工製程和儲藏條件，維持β-carotene的含量，並針對維生素A得到較佳的有效性年限。
利用橘色果肉品種的甘薯以開放式太陽乾燥，密閉式乾燥，以及熱風乾燥的加工條件。將清洗過後的甘薯的根分別以2，4和6毫米的厚度作切片，然後以沸水浴作2，4和6分鐘的殺菁處理並使其漂白；然後將先前處理過的放到乾紙巾擦乾後作乾燥。然後以最適化的乾燥條件的產品切片，分別以溫度在150，160及170℃之下，利用電熱油炸60，70以及90秒。所使用的油分別有三種，包括有紅棕櫚油(red palm oil; RPO)、花生油 (peanut oil; PO)以及這兩種的混合油(80％PO,20％RPO)。甘薯和花生油分別由台灣省屏東縣內埔鄉當地的市場購得，紅棕櫚油則是用西非(Burkina Faso, and Senegal)購得。研究利用田口方法針以L9(34)直角表對四個因子三個水準，分別對乾燥條件，油炸和儲藏過程作實驗。並以液相層析(HPLC)分析監測β-carotene的含量。
我們利用信號雜訊比(the signal to noise ratio; S/N ratio)作分析，研究指出控制因子以2毫米甘薯切片，以熱風乾燥方式在45℃下作乾燥可以得到較佳的成品。確認試驗中可以比先前實驗增大到45%β-carotene的產率。其中並指出殺菁的處理是影響乾燥甘薯片β-carotene含量的主要因子。相反的，乾燥效率會受甘薯切片厚度和乾燥溫度所影響。根據S/N ratio回應圖指出在油炸期間以含20%RPO的混合油，在50-60℃加熱，油炸時間75秒可以得到最好的品質，可保留更多的β-carotene。然而在室溫和4℃儲藏4星期後指出有不同的趨勢。研究指出四星期的儲藏期間會使順式cis形成反式trans的異構物而增加β-carotene的含量。可是4星期可能仍不夠長足以使這個反應達到平衡，並且會決定油炸甘薯片β-carotene變化的趨勢。而且β-carotene和顏色的組成(L*, b*)，色調(hue angle)和顏色飽和度(chroma)有非常顯著地的相關性(p < 0.0001)。

The deficiency of Vitamin A is an endemic public health problem which increases the mortality of children under the age of five in many developing countries, especially in Africa. Among the alternatives to alleviate this problem, food-based approaches are agreed to be the most sustainable measures.
Plant origin provitamin A, carotenoids are the most accessible to the poor and represent 80% of the vitamin A intake in developing countries. However, these plants in most developing countries occur seasonally. Moreover, carotenoids are very sensitive to light, heat and oxygen.
The main objective of this study was to develop appropriate processing and storage conditions of sweet potatoes that would concentrate and preserve the β-carotene, for a better availability of vitamin A year round; thus contributing to the improvement of vitamin A intake in needy areas.
Orange-fleshed sweet potato roots were dried under open sun-drying, closed-type drying, and hot-air drying conditions. Fresh roots were washed, sliced at 2, 4 and 6 mm, then blanched in boiling water for 2, 4, and 6 min; then after drained on paper toweling prior to drying. The resulting chips from optimized drying conditions were fried using a home electric fryer, with temperature settings at 150, 160, and 170 °C for 60, 75, and 90 sec. Three categories of oil; including red palm oil (RPO), peanut oil (PO), and a blend of these two (BO) at 20% RPO were used. Sweet potatoes and PO were purchased from a local market in Pintung city, Taiwan, and RPO was obtained from West Africa (Burkina Faso, and Senegal). We used a Taguchi orthogonal array [L9(34)] for the drying, and the frying and storage experiments. The β-carotene content was monitored using HPLC
Our results using the signal to noise ratio (S/N) analysis indicated that 2 mm sweet potato slice, blanched in hot for four min, and dried in hot-air dryer at 45 °C was the best combination of control factors. A confirmation run yielded a 45% β-carotene increase as compared to the best predefined treatment. Blanching pretreatment appeared to be the most influential factor that determined the β-carotene retention in dried chips. Conversely, the drying efficiency was found to be governed by sweet potato slice thickness and drying temperature. Based on the S/R ratio at base-line, 20% RPO blend oil, heated at 150 to 160 °C for a 75 sec frying time, retained more β-carotene during the frying process. However storage at room temperature and 4 °C showed different trends after 4 weeks. It appeared that, the 4 weeks storage time favored cis to trans isomerization that increased the all-trans-β-carotene content. However, 4 weeks were likely not long enough to stabilize the reactions and to determine a definite trend to the change of β-carotene in fried chips. The color components (L*, b*), and hue angle and chroma were positively and highly correlated (p < 0.0001) to β-carotene content.

CHINESE ABSTRACT 中文摘要………………………………………
ABSTRACT……………………………………………………………...
ACKNOWLEDGEMENTS………………………………………………
TABLE OF CONTENTS………………………………………………...
LISTE OF TABLES……………………………………………………...
LISTE OF FIGURES……………………………………………………..
1 INTRODUCTION……………………………………………………...
2 LITERATURE REVIEW………………………………………………
2.1 Role and Importance of Vitamin A………………………………...
2.2 Occurrence and impact of vitamin A deficiency…………………...
2.3 Importance of Carotenoids…………………....................................
2.4 Vitamin A Toxicity……………………………….………………..
2.5 Strategies to Combat Vitamin A deficiency………………………..
2.6 Natural Sources of Vitamin A……………………………………...
2.7 Health Benefit of Carotenoids……………………………………...
2.8 Sweet Potato and its’ Vitamin A Potential…………………………
2.9 Fats, and Oils, and Bioavailability of Vitamin A…………………..
2.9.1 Peanut oil………………………………………………………
2.9.2 Red palm oil……………………………………………………
2.10 Food Processing and Vitamin A Preservation…………………...
2.10.1 Boiling………………………………………………………..
2.10.2 Drying………………………………………………………...
2.10.3 Deep-fat frying………………………………………………..
2.10.4 Storage………………………………………………………..
2.11 Research Methodology…………………………………………...
3 MATERIALS AND METHODS………………………………………
3.1 Materials……………………………………………………………
3.1.1 Raw materials………………………………………………….
3.1.2 List of chemicals and reagents………………………………....
3.1.3 List of equipments……………………………………………..
3.2 Methods…………………………………………………………….
3.2.1 Drying process………………………………………………....
3.2.2 Frying and Storage processes………………………………….
3.2.3 Color measurement…………………………………………….
3.2.4 Beta-carotene extraction and analysis protocol………………..
3.2.4.1 Preparation of samples for β-carotene extraction………….
3.2.4.2 β-Carotene extraction procedure…………………………..
3.2.4.3 Sample analysis…………………………………………....
3.2.4.4 HPLC conditions…………………………………………..
3.3 Experimental design and data analysis…………………………….
4 RESULTS AND DISCUSSION………………………………………..
4.1 The drying experiment……………………………………………..
4.1.1 Effect of control factors on the β-carotene retention of sweet
potato slices……………………………………………………
4.1.2 Effect of slice thickness and drying temperature on the
efficiency of drying systems…………………………………..
4.1.3 Drying characteristic of sweet potato slices…………………...
4.1.4 Color parameters (CIE L*, a*, b* and hue angle and chroma)
evolution during drying process in relation to β-carotene
content…………………………………………………………
4.2 The frying and storage experiment…………………………………
4.2.1 Effect of the frying treatment on the physical characteristics
of sweet potato fried chips…………………………………….
4.2.2 Effect of frying on the beta-carotene retention in sweet potato
chips……………………………………...……..……………..
4.2.3 Change of the β-carotene concentration during storage……….
4.2.4 Color parameters (CIE L*, a*, b* and hue angle and chroma)
evolution during frying and storage process in relation to
β-carotene content……………………………………………..
4.2.5 Evaluation of the nutritional value of sweet potato fried chips.
5 CONCLUSIONS……………………………………………………….
REFERENCES…………………………………………………………...
APPENDIX 1…………………………………………………………….
APPENDIX 2…………………………………………………………….
BIO-SKETCH OF THE AUTHOR……………………………………… I
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