Changes in Fatty Acid Composition and Phytosterol Content in Double Cropping Maize

The average growth day of 11 maize varieties from planting to silking in the first cropping (FC) was 89.5 days and in the second cropping (SC) was 46.7 days, which was 43 days faster than in the FC. The average 100-kernel weight (100 KW) in the FC was 28.4 g and 18.3 g in the SC, which was approximately 36.4% lower than that in the FC. The average crude oil content of FC was 3.97% and SC was 3.08%, which was about 0.89% lower than that of FC. The composition of stearic and oleic acid was significantly higher in FC, whereas palmitic and linoleic acid were higher in SC; however, linolenic acid was not statistically different between the two crops. The crude oil content was negatively correlated with linoleic acid (FC -0.264^ns, SC -0.504**) and positively correlated with linolenic acid (0.526**). Unsaturated fatty acid (USFA) composition showed a significant difference between FC (83.48%) and SC (82.96%). Total phytosterol content was 598.3 mg/100 g and 701.9 mg/100 g in FC and SC, respectively, and showed significant difference by planting dates. The β-sitosterol content showed no statistical difference between the planting dates, but campesterol and stigmasterol were significantly higher in SC than in FC. Therefore, it was considered that the temperature condition during the ripening period affects the 100 KW of maize, and this leads to the variation in phytosterol content. However, among phytosterols, β-sitosterol was relatively little affected by the planting dates. USFA composition showed a significantly negative correlation with phytosterol content. Considering the results, the relatively high phytosterol content in SC was mainly because of the delay in progress of starch accumulation as daily air temperature decreased from the middle of the ripening period, whereas progress of phytosterol accumulation in the maize kernel was considered relatively faster than that of starch accumulation.

이기작에 따른 옥수수의 지방산 조성 및 Phytosterol 함량 변화

옥수수 이기작에 따른 종실의 지방산조성과 phytosterol 함량의 변화를 검토하여 이기작의 조기정착화 및 수확된 농산물의 부가가치 향상을 위한 기초자료로 활용하고자 본 연구를 실시하여 얻어진 결과를 요약하면 다음과 같다. 1. 전기작(4월 10일 파종) 옥수수 11품종의 평균 출사일수는 89.5일이었고, 후기작(7월 30일 파종) 옥수수의 평균 출사일수는 46.7일로서 후기작의 출사일수가 전기작에 비해 약 43일 빨랐다. 2. 전기작 옥수수 11품종의 평균 백립중은 28.4 g이었으나 후기작은 18.1 g으로 전기작에 비해 약 10.3 g (36.4%) 백립중이 감소되었고, 조지방 함량은 전기작이 3.97%, 후기작은 3.08%로서 전기작에 비해 약 0.89% 함량이 낮았다. 3. 전기작 옥수수의 지방산 조성은 linoleic 51.66% > oleic 29.52% > palmitic 14.33% > linolenic 2.30% > stearic acid 2.18%이었고, 후기작은 linoleic 53.06% > oleic 27.33% > palmitic 15.43% > linolenic 2.58% > stearic acid 1.61% 였다. 4. Stearic과 oleic acid의 조성비는 전기작이 통계적으로 유의하게 높았고, palmitic과 linoleic acid는 후기작이 높았으나 linolenic acid는 차이가 없었다. 5. 조지방 함량은 전·후기작 모두 linoleic acid와 부상관(전기작 -0.264^ns, 후기작 -0.504**), linolenic acid와 정상관(0.526**)이 있었고, 불포화지방산 비율은 전기작 83.48%, 후기작 82.96%로서 이기작에 따른 유의차가 있었다. 6. 총 phytosterol 함량은 전기작이 598.3 mg/100g, 후기작은 701.9 mg/100g으로 이기작에 따른 유의차가 있었고, β-sitosterol은 이기작간 차이가 없었으나 campesterol 및 stigmasterol은 후기작의 함량이 전기작 보다 유의하게 높았으며, 불포화지방산은 phytosterol 함량과 전·후기작모두 유의한 부의 상관(전기작 -0.346*, 후기작 -0.468**)을 보였다. 7. Phytosterol 함량이 후기작에서 높았던 것은 등숙 중기부터 기온이 저하되면서 전분축적이 지연되어 종실의 충실도가 낮아진 반면 phytosterol은 전분보다 상대적으로 빠르게 종실 축적이 이루어졌기 때문인 것으로 사료되었다.