한국 지리산권 덖음녹차의 살청 온도에 따른 품질 특성 = Quality Characteristics of Pan-Fired Green Tea from the Jirisan Region of Korea as Affected by Fixation Temperature

다국어 초록 (Multilingual Abstract)

This study investigated the effects of fixation (pan-firing) temperature on the physicochemical and sensory-related properties of traditionally processed green tea produced in the Jirisan region of Korea. Twelve green tea samples manufactured by traditional pan-firing in major production areas (Hadong, Gurye, Namwon, and Sancheong) were classified into three groups according to fixation temperature: low (A, 100–200 °C), medium (B, 200–300 °C), and high (C, 300–400 °C). Color parameters (L*, a* and b*), chlorophylls and pheophytin, total carotenoids, antioxidant activities (DPPH, ABTS), total polyphenols (TPC), total flavonoids (TFC), catechins and caffeine (HPLC-DAD), free sugars (HPLC-RID), free amino acids (HPLC-FLR), and taste attributes measured by an electronic tongue were evaluated. Low- and medium-temperature treatments maintained high L* values and negative a* values, preserving the typical green color, whereas high-temperature treatment led to a marked decrease in L*, a shift of a* to positive values, and reduced b*, indicating pronounced browning. Total chlorophylls were unstable at low temperature due to residual enzyme activity and were rapidly degraded at high temperature via thermal pheophytinization, while medium temperature showed the greatest chlorophyll retention. Total carotenoids were highest in the medium-temperature group and decreased sharply at high temperature due to thermal oxidation. Antioxidant activities, TPC, and TFC exhibited non-linear responses: they were generally stable at low temperature, increased or were maintained at medium temperature due to enhanced extractability of bound phenolics, and then declined at high temperature because of thermal degradation and oxidation. Catechin and caffeine profiles showed large sample-to-sample variability, and gallic acid–esterified catechins did not follow a simple monotonic temperature trend, reflecting the combined effects of degradation and epimerization. Free sugars (especially sucrose, glucose, and fructose) were highest at medium temperature and were strongly reduced at high temperature, likely due to hydrolysis and Maillard-type reactions. Medium-temperature samples also showed relatively higher levels of theanine, glutamic acid, and other umami-related amino acids, whereas some amino acids decreased under high-temperature conditions. Electronic tongue analysis revealed that the medium-temperature group had the most balanced taste profile (umami, bitterness, astringency, sweetness, and saltiness), while low temperature produced a more unbalanced taste and high temperature resulted in generally weakened taste intensity. Overall, these results indicate that fixation temperature is a key processing parameter governing color, pigment stability, bioactive components, and taste properties of Jirisan green tea, and that the medium-temperature range of 200–300 °C provides an optimal balance between quality preservation and flavor development.

목차 (Table of Contents)

• I. 서론 5
• Ⅱ. 재료 및 방법 8
• 1. 시료 준비 8
• 2. 색도 10
• 3. Total chiorophylls 및 total Pheophytin 분석 10
• 4. Total carotenoids 분석 11
• 5. DPPH 및 ABTS radical scavenging activities 분석 12
• 6. Total polyphenol 및 total flavonoid 분석 13
• 7. Catechin 및 caffeine 분석 14
• 8. Free Sugar 분석 15
• 9. Free Amino acid 분석 16
• 10. 전자혀(Electronic Tongue) 분석 17
• 11. 통계 분석 17
• Ⅲ. 결과 및 고찰 18
• 1. 살청 온도에 따른 녹차의 색도 18
• 2. 살청 온도에 따른 녹차의 total chlorophylls 및 pheophytin함량 21
• 3.살청 온도에 따른 녹차의 total carotenoids 함량 25
• 4. 살청 온도에 따른 녹차의 항산화 활성 28
• 5. 살청 온도에 따른 녹차의 total polyphenol 함량 32
• 6. 살청 온도에 따른 녹차의 total flavonoid 함량 33
• 7. 살청 온도에 따른 녹차의 catechin 및 caffeine 함량 36
• 8. 살청 온도에 따른 녹차의 Free Sugar 함량 39
• 9. 살청 온도에 따른 녹차의 Free Amino acid 함량 42
• 10. 살청 온도에 따른 녹차의 전자혀 (Electronic Tongue)분석 46
• 11. 살청 온도에 따른 녹차의 유효성분 상관분석 48
• Ⅳ. 요약 50