冷凍用青花菜品質及產量改進方法之研究

Studies on the Improvements of Quality and Yield of Frozen Broccoli

本研究目的在於探究影響冷凍用青花菜品質及產量之因子作為生不改進之依據，以利加速發展台灣青花菜之冷凍加工事業，調節夏季內銷市場之供銷歐美市場爭取外匯。早生，中生品質青花菜均可在科冬季隨時播種，栽培供冷凍之用，其中尤以Pacifica, Fengshan, Spartan Early品種，苔梗較短，花蕾緊密，空心率低，解凍後之品質良好，Fengshan, Sapartan Early株型較矮小，宜以密植栽培提高其單位積產量。株距25cm比30cm之產量高過10%以上，行距50cm比65cm之產量高18%左右，但以畦溝行距60cm，畦上行距40cm，株距25cm為最合理。但株距愈多，菜苔之空心率亦愈高。定植前每10公畝施硼砂1公斤作基肥。株距25cm，生育後期灌水用量不過多，可減少菜苔空心百分率。採收後青花菜貯藏在不同溫度下，其貯藏壽命及貯藏期間所產生之CO2總量幾乎相同。每公斤青花菜累積到20,000mg左右則會結束其貯藏壽命。貯藏溫度在20℃下。其平均呼吸量為每公斤每小時放出234.4mg CO2時，只需3.6天即失去商品價值；在10℃下，其平均呼吸量為每公斤每小時91.5mg CO2時。約經10天即失去商品價值；在0℃下。其平均呼吸量為每公斤每小時19.0mg CO2時，可維持45天左右之壽命。為保持青花菜之新鮮及品質之良好，採收後之青花菜應以最迅速之方法送至加工廠予以快速冷凍加工或低溫貯藏。

The purposes of this study were to ascertain the factors affecting the quality and yield of frozen broccoli (Brassica oleracea var. italica) to improve and develop frozen broccoli industry in Taiwan. Four experiments including (1) Varietal trial for frozen broccoli, (2) Close planting of broccoli, (3) Prevention of broccoli hollow stems, (4) Post-harvest handling practices were carried out in this study. The experimental results were summarized as follow: 1. 13 varieties such as Green Sprouting Improved, Spartan Early, Hybrid 10, Topper 43, Medium 90, Medium Late 143, Medium Late 423, Express Corona, Pacifica, Decicco, Green Mountain, Fengshan, Calabrese were tested in this study. Besides late varieties such as Medium Late 143 and Medium Late 423, which could not easily develop inflorescence due to insufficient low temperature in southern part of Taiwan, all early and medium varieties could be sowed at any time during winter season foe economic production. 2. The material of frozen broccoli should be compact heads with dark green color and short peduncle but without hollow stem, insect injury and decay. Varieties such as Pacifica, Fengshan, Spartan Early which had shorter peduncle, compact heads, low percentage of hollow stems and good quality after defrozen, are promising. However, they are also necessary to continue acclimatization selection, purification and make hybrid combination. 3. In general, shorter plants had shorter peduncles and lower yield but suit for close planting due to their upright leaves and few lateral sproutings. Variety, Fengshan and Spartan Early are belong to this type, they are recommended to be planted more closely to raise yield per unit acreage. 4. Spacing treatments in this study had a signigficant effect on yield of broccoli. General speaking, the smaller spacing in plants or between rows they were the smaller heads they got, but also the higher yield they could get due to the increment of plant population. The average yield they could get due to the increment of plant population. The average yield from the plot of 25 cm apart in plants was 10% higher than that from the plot of 30 cm apart in plants. The average yield from the plot of 50 cm apart between rows was 18% higher than that from the plot of 65 cm apart between rows. However, there was no great difference between treatments of 50×25 cm and (The equation is abbreviated)×25cm. For the convenience of field operation, we recommend the latter, i.e., spacing of 60 cm apart between rows on the furrow, 40 cm apart between rows on the ridge, and 25 cm apart in plants are reasonable. 5. The material for frozen broccoli should be cut into a half or a quarter. If they were hollow stems after cutting, they would not be good frozen products. Based on the results of analysis of varience, the amount of irrigation and the size of plant spacing had greater effect on the percentage of hollow stems i.e., more irrigation we applied or the larger spacing we planted, the higher percentage of hollow stems we obtained. However, the interaction among the amount of borax, the size of plant spacing and the amount of irrigation were not significant. 6. In order to promote the quality of frozen broccoli, the following three points should be paid to attention when broccoli plants are grown. (1) Before planting, one kilogram of boras should be applied as basic manure on acreage of 10 are (2) Spacing of 25 cm apart in plants would be recommended, (3) The amount of irrigation during the late stage should be decreased for the decrement or prevention of hollow stems. 7. Since broccoli is one of the most perishable vegetables, the quality would be deteriorated very remarkably if broccoli heads were handled un-properly after harvesting. Especially, for the factor of temperature, i.e., the higher temperature of holding they were, the higher respiration rate of products they got, and the higher speed of quality deterioration they lost, Based on the measurement of this experiment, the total amount of CO2 produced during the period of shelf life at any temperature of storage would be almost the same, i.e., one kilogram by weight of broccoli would end its storage life if the CO2 production accumulated to about 20,000 mg. Under the condition of 20℃, the average respiratory rate was 234.4 mg CO2/kg/hr., it took only 3.6 days to loss its marketability; under the condition of 10℃, the average respiratory rate was 91.5 mg CO2/kg/hr., it would take 10 days to loss its marketability, while under the condition of 0℃, the average respiratory rate was 19.0 mg CO2/kg/hr., it could keep the market value for 45 days. 8. According to the respiratory information measured by this experiment, the Q10 of the physiological reaction of harvested broccoli were not the same as that of the pure chemical reaction, but they were close to constant (2-3 fold). In general, the Q10 of harvested broccoli under the conditions of low temperature are inclined to be high. In other word, the effect of cold storage of broccoli was very great. Based on the information of Arrhenius equation, a theortical straight line almost could be plotted. In order to keep the freshness and good quality of broccoli, it is very important that the harvested broccoli should be sent to frozen factory as soon as possible.