台灣紅豆,幸福飄香

:::

2012 / 11月

文‧朱立群 圖‧金宏澔


十月是播種「幸福」的季節!來年一月收成的紅豆,就是幸福的果實。

台灣紅豆今年隨星巴克咖啡與珍珠奶茶一起飄香海外,身處異鄉,也能嚐到正宗台灣紅豆的幸福滋味。


9月底,一場颱風前腳剛走,屏東縣萬丹鄉清晨的天空清澈了起來。空氣中淡淡的濕氣,捎來秋天降臨南國的消息。

二期稻作才剛完成採收、整地呢,幾位農民就已起個大早,開著曳引機或耕耘機在田裡來回開溝、作畦,為紅豆播種揭開序幕。

紅豆又稱小豆或赤豆,屬一年生草本植物,原產於中國大陸喜馬拉雅山,目前全球以大陸、日本、台灣、韓國為主要種植地區,印度、東南亞、加拿大、美國也有少量生產。

台灣在2002年加入世界貿易組織(WTO),迄今持續實施關稅配額管制紅豆進口,並禁止從大陸輸入,每年總進口量約4,000公噸。

喜馬拉雅山上的紅豆何時引進台灣,起源已不可考。一般認為,早期的在來種紅豆僅在山區零星栽種,1960年在屏東秋季種植之後,始成為經濟性栽培的作物。

幸福,秋天降臨

春耕、夏耘、秋收、冬藏,一般而言,稻米等主要糧食作物不在秋、冬耕作。但雜糧作物可於秋、冬時節栽種,稱為秋、冬「裡作」。在台灣,紅豆是重要的秋季裡作作物,每年9月下旬至10月中旬,農民在二期稻作收成後的田裡播下種子,3個月後即可採收豆莢。

紅豆適合秋天種植,有其作物氣候學上的道理。專研紅豆生產與品種改良的農委會高雄區農業改良場助理研究員陳玉如表示,紅豆生長需要「先熱後涼」的天氣,尤其中期豆莢開始膨脹、充實之後,溫度如果太高,結出的紅豆就越小粒。換言之,初秋氣候尚留夏季高溫的熱氣,之後便緩緩進入冷涼的季節,最適合紅豆生長。

根據農委會的統計,紅豆是台灣的第4大雜糧作物,目前總生產面積約5,600公頃,種植面積僅次於落花生、食用玉蜀黍及甘薯,估計年產值超過新台幣5億3,000萬元。

與綠豆相較,紅豆去年的種植面積是綠豆的112倍(5,600 vs. 50公頃),產量相差267倍(11,498 vs. 43公噸),兩者的生產規模天差地別。

屏東縣是國產紅豆的生產重鎮,栽種面積及產量皆占全國的9成以上。位在高雄、屏東交界的農委會高雄區農業改良場,肩負紅豆品種改良的重任,以雜交育種的方式提升紅豆的品質,今年7月推出的最新品種──高雄10號「紅玉」,現正準備進入技轉、商業化種植的階段,最快明年秋天就能播種入土。

高雄9號目前仍是最受農友與消費者青睞的紅豆品種,約占總種植面積的六成;明年一月搶鮮上市的,就是這款被命名「紅寶」商業品牌的幸福果實。

雜交育種,十年磨一劍

紅寶與紅玉的育種研發者陳玉如,一語道破紅豆育種改良所追求的終極目標:「顏色要更漂亮、豆形要更大顆。」

陳玉如說,鮮紅色是紅豆的最佳色澤;每百粒豆重量小於14公克被歸類為小粒,14.1~17公克為中粒,17.1~20公克算是大粒,20.1公克以上則屬特大粒。

59歲的陳玉如自1987年調任高雄場迄今,投入紅豆改良工作長達25年,高雄5號是她交出的第一張成績單,後續新品種的育成,也都由她親手操刀。她去年榮獲台灣農藝學會頒發的個人事業成就獎,受推崇是台灣紅豆產業的推手。

「新的品種從育種到問世,都得耗時10年以上,」陳玉如說。「對紅豆親本的瞭解越透徹,越能掌握子代性狀的表現。」

她解釋說,紅豆育種過程之所以耗時漫長,一來因為1年只有1次田間試驗的機會(秋裡作),二來事先須對雜交的紅豆親本追本溯源,爬梳它們的祖宗八代,任何跟遺傳有關的細節都不能錯過。

宛如優生學,如果每一次的紅豆雜交育種,都在試圖留下親本最優秀的特徵,並表現在新品種上,那麼,台灣的紅豆至今經歷過哪些去蕪存菁的改良?

好,還要更好

回顧台灣紅豆品種的演進,1974年命名的高雄選1號揮出第一棒,後續接棒者包括高雄2、3,及5~10號,都是朝著更紅、更大顆的方向進化。

距今38年前(1974年),高雄農改場首度發表並命名高雄選1號。這個品種具呈色亮紅的優點,唯屬小粒種、每百粒重量低於14克的瑕疵仍不讓人滿意。

此外,高雄選1號易受白粉菌的侵害而感染白粉病,發病時,豆葉表面被裹上一層狀似白粉的物質,會阻礙植物行光合作用,導致植株生長受阻、豆莢不飽實。

1980年初,高雄場陸續育成高雄2號與3號紅豆,但與高雄選1號一樣,具顆粒小、產量不豐的致命弱點。

1988年發表的高雄5號,是陳玉如參與紅豆改良的處女作。該品種以屏東在來種為母本、高雄選1號為父本進行雜交,結合前者產量穩定、後者顏色鮮紅的優點,所育成的植株較早期品種挺拔、不易倒伏;與之前的品種相較,高雄5號產量增加10~15%,豆子外皮較薄,口感較綿密,香氣也較濃。

為了精進國產紅豆的品質,有必要從國外引進適合雜交的親代品種。高雄5號問世後,陳玉如與同事以其為母代,另以從日本的紅豆聖地──北海道引進的「壽小豆」為父本,實施人工雜交育種。然而,壽小豆雖有產量高、豆體比高雄5號大粒的優點,卻掩飾不了外表色澤暗沉、植株體型較矮的缺陷。

經過後代的分離、純化,高雄6號在1993年問世,它的體型均勻、大小一致,並承繼了母本高雄5號色澤鮮紅的特色。

進行育種的過程中,陳玉如認為所有的品系都有優、缺點,包括被淘汰的失敗者、與高雄5號出自同一對父母的KS540紅豆品系。

KS540色澤偏暗、不討喜,但體型比高雄5號碩大,是一大優勢。陳玉如選擇以此遺珠品系為母本,佐以日本大粒種「美甘大納言」為父本,於1998年發表高雄7號,為高雄場成功改良的第一個大粒紅豆品種。

除了致力品種改良,研發單位也在病蟲害防治上耗費不少心力,其中,白粉病與薊馬是田間常見的災難,也是農友心裡最大的痛。

高雄場自1990年起即著手改良,以場內選育的KA79-02-27品系與日本美甘大納言為親本,2002年發表的高雄8號紅豆,可大幅降低田間病蟲害的發生率與防治成本,唯其種粒較小(屬於中粒種)是一大缺憾。

於是,高雄場針對高雄8號的豆粒大小加以改良,在2006年發表高雄9號(紅寶),百粒重量可達23公克,是該場迄今育成顆粒最大的紅豆商業化栽培品種,甫問世,國內外農友即不斷探詢取得種子的可行性。

早期,高雄場直接把紅豆的研發成果推廣給農友,此舉間接導致品種外流嚴重,但從高雄9號開始,改將新品種技轉育苗機構,由其再做推廣;也是從高雄9號開始,不再公開育種的親本來源,以保障作物的品種權。

高雄場7月發表的最新紅豆品種高雄10號(紅玉),豆體不但比紅寶稍大,色澤也較紅,其外觀、賣相都是迄今品質最佳的國產紅豆。

加工紅豆甜蜜蜜

根據農委會的統計,以紅豆及其加工製品來說,國內每年約有1萬2,000公噸的消費需求,其中約8,000公噸由國產紅豆供應。

屏東萬丹是全國規模最大的紅豆生產基地。萬丹鄉農會表示,若沒有發生雨災,其下所屬的13個產銷班,年產量可達四千多公噸,其中4成供應乾豆市場,6成則製成蜜紅豆、紅豆湯等加工食品。

國產紅豆的產量光是供應國內市場就已捉襟見肘,外銷不多,雖拚不過大陸出口的低價紅豆,但國際知名度已逐漸提高。與屏東紅豆產地密切合作的聯夏食品公司表示,訂單除了來自美國、加拿大等國,國際知名咖啡連鎖店星巴克今年更指名選購台灣紅豆,供亞太地區門市當作紅豆抹茶飲品的配料使用。

另外像高雄的紅豆產地大寮,去年推出全國第一個通過產銷履歷認證的「紅晶鑽」乾紅豆,大受民眾歡迎。大寮農會表示,國內一年至少賣出10萬公斤,且目前正在洽談出口汶萊的訂單。

相較於進口紅豆,國產紅豆的品質優勢為何?

高雄區農改場助理研究員陳玉如表示,論外觀,國產紅豆較大顆,進口紅豆則幾乎都是小粒種;論口感,國產紅豆較綿密,進口紅豆則是硬粒太多、入口猶如咬到石頭;論香氣,國產紅豆不加糖就能散發天然豆香。

此刻正是裡作紅豆生長的季節。等到明年一月走一趟屏東、高雄,帶回新鮮且原汁原味的台灣紅豆,烹煮後,滿室都是幸福的氣氛。

品嚐幸福的滋味無需遠行,台灣紅豆就在身邊。

相關文章

近期文章

EN

The Joys of Taiwan-Grown Adzuki Beans

Sam Ju /photos courtesy of Chin Hung-hao /tr. by Jonathan Barnard

October is the month for sowing seeds of joy! And the adzuki beans that are harvested the following January represent that joy coming to fruition.


Adzuki beans, which are known in Chinese as “red beans” or “little beans,” are annual plants native to the Himalayan Mountains. Mainland China, Japan, Taiwan and Korea comprise the main places the beans are cultivated. Smaller amounts are grown in India, Southeast Asia, Canada, and the United States.

Since Taiwan joined the WTO in 2002, it has maintained tariff rate quotas on adzuki beans and banned all imports of them from mainland China. Total imports of the beans have averaged about 4,000 metric tons per year.

It is not entirely certain how these red beans from the Himalayas made it to Taiwan. It’s generally thought that adzuki beans were first planted only in high-elevation areas here. It wasn’t until the beans were planted as a fall crop in Pingtung in 1960 that they became an important cash crop.

Joy descends in the fall

Generally speaking, rice isn’t planted in the fall and winter in Taiwan. That’s the time instead for various non-rice staple crops, including adzuki beans. From the end of September to the middle of October, farmers sow the adzuki seeds after harvesting the second crop of rice from their paddy fields. Then they harvest the beans three months later.

Chen Yu-ju, a researcher with the Council of Agriculture’s Kaohsiung District Agricultural Research and Extension Station, explains that adzuki requires weather that’s “first hot and then cold.” Especially when the pods begin to fatten, if the weather is too hot, the pods will be smaller. In other words, the most suitable time to plant adzuki is in the early fall before the warmth of summer has entirely dissipated. Then the weather can gradually cool to the chill of winter.

According to COA statistics, adzuki beans are the nation’s fourth most important “non-rice staple.” Currently, 5,600 hectares of adzuki are under cultivation each year, behind only peanuts, corn (maize) and sweet potato. Its total value is estimated at NT$530 million.

Surprisingly, though most Taiwanese think of green mung beans and adzuki beans as comparable products, the area of adzuki under cultivation in 2011 was 112 times as large as that for green mung beans (5600 to 50 hectares) and the quantity harvested was 267 times as large (11,498 to 43 metric tons). Among beans, adzuki are in a league of their own.

Pingtung County is the center of Taiwan’s adzuki bean farming, accounting for more than nine-tenths of total production. Located near the border of Kaohsiung and Pingtung, the COA’s Kaohsiung District Agricultural Research and Extension Station is responsible for improving adzuki strains. In July of this year, it released a new variety: Kaohsiung No. 10 (“Red Jade”). It is now entering the phase of technology transfer and commercialization. The strain may be cultivated commercially as early as next fall.

Kaohsiung No. 9 (“Red Treasure”) is currently the variety of adzuki most favored by farmers and consumers in Taiwan. It accounts for about 60% of the area under cultivation.

A decade of crossbreeding

This is how Chen Yu-ju, the researcher behind the development of both “Red Treasure” and “Red Jade,” sums up the ultimate goal of adzuki breeding: “To attain a prettier color and a fatter bean.”

Chen says that bright red is adzuki’s ideal color. In terms of weight, if 100 beans weigh 14 grams or less, then the variety is regarded as small; at 14.1–17 grams it is regarded as medium sized; at 17.1–20 it’s large; and at 20.1 and over it’s extra-large.

“From the start of breeding to release, the process of developing a new variety takes 10 years,” explains Chen. “The breeding has always taken so long because each year you only get one chance to plant in the fields—in the fall,” she explains. “What’s more, you’ve first got to do thorough research into a bean’s ancestors. You can’t overlook any detail of its genetic heritage, since the more you know about the ancestors, the more you can control the characteristics of the descendants.”

So what improvements have been made to adzuki bean varieties in Taiwan so far?

When one examines the evolution of adzuki beans in Taiwan, Kaoshiung No. 1, which was introduced in 1974, is the place to start. Its descendants include Kaohsiung Nos. 2, 3 and 5­­–10. Each is larger and brighter red than its predecessors.

It was just 38 years ago, in 1974, that the COA’s Kaohsiung District Agricultural Research and Extension Station introduced Kaohsiung No. 1. The variety was bright red, but had a significant flaw: It was small, with 100 of its beans weighing less than 14 grams.

What’s more, Kaohsiung No. 1 was highly susceptible to powdery mildew fungal disease. When afflicted, the leaves of adzuki plants become covered with a powdery white film that impedes photosynthesis, leading to stunted growth and lower yields.

Early in 1980 the Kaohsiung Station released Nos. 2 and 3 in rapid succession. But like No. 1, they had the flaws of being small and offering only low yields.

Kaohsiung No. 5, released in 1988, was the first variety that Chen worked on. It was crossbred from a Pingtung variety and Kaohsiung No. 1. It combines the steady yields of the former with the bright red coloration of the latter. The plants tend to grow taller and straighter than earlier varieties, and they aren’t easily toppled over. In comparison to earlier varieties, Kaoshiung No. 5 offers increased yields of 10–15%. The beans also have thinner skins. Their mouthfeel, moreover, is more refined, and they feature a stronger fragrance.

Cross-cultural arranged weddings

In order to advance the quality of Taiwan’s adzuki beans, it has been necessary to import varieties from abroad to use for crossbreeding. After Kaohsiung No. 5 was released, Chen and her colleagues began to crossbreed it with a variety from Hokkaido, Japan. Although the Japanese variety offered high yields and its large beans were regarded as superior to Kaohsiung No. 5, it had its own drawbacks: a dark coloration and shorter plants.

After selection and purification over the following generations, Kaohsiung No. 6 was released in 1993. It offers plants of extremely uniform size. Moreover, it inherited the bright red of its mother, Kaohsiung No. 5.

Chen believes that for breeding purposes all strains have their good points and bad points, including KS540, a rejected variety that shares parents with Kaohsiung No. 5.

KS540’s dark coloration is not appealing to people, but the plants are larger than Kaohsiung No. 5. Taking that unappreciated variety as the mother and “Mikandainagon,” a Japanese variety, as the father, Chen was able to develop a new strain: Kaohsiung No. 7, the first of the large-seeded varieties released by the research station, which was launched in 1998.

Apart from working hard to improve strains, the research station has also spent a lot of energy fighting damage from disease and pests. In particular, powdery mildew and chilli thrips commonly inflict devastation in adzuki fields.

Since 1990 the Kaohsiung research station has thrown itself into disease-prevention work. By crossbreeding KA79-02-07, a variety it developed itself, with the Japanese Mikandainagon, it was able release Kaohsiung No. 8 in 2002. This variety greatly reduces the problem of field pests and the costs associated with disease and pest control. Nevertheless, its smaller beans (ranked as medium size) represent a big flaw.

Consequently, the Kaohsiung research station subsequently focused on improving the size of Kaohsiung No. 8 beans and released Kaohsiung No. 9 (“Red Treasure”) in 2006. Its beans weigh in at 23 grams per 100, making it the largest of the station’s adzuki varieties to date. Since its release, domestic and foreign farmers alike have been continually inquiring about the possibility of obtaining seeds.

In July of this year the research station issued its newest varietal release: Kaohsiung No. 10 (“Red Jade”). With its coloration, overall appearance, and sales appeal, it’s the best variety developed in Taiwan so far.

Processed adzuki

According to the COA, in Taiwan there is annual demand for 12,000 metric tons of adzuki beans and related processed goods. About 8000 tons of that is met from local production.

Pingtung County’s Wandan grows the most adzuki beans in Taiwan. The township’s farmers’ association explains that barring unusual rain damage, its 13 production cooperatives will harvest more than 4000 metric tons each season. About four-tenths of that is put on the commodity market, and about six-tenths is sold directly to processed food manufacturers to make adzuki bean paste and other processed foods.

The domestic market takes almost all of local adzuki bean production, and very little is exported. Although it’s hard for Taiwan-produced adzuki beans to compete on the international market with low-priced beans from mainland China, the international reputation of Taiwan adzuki beans is steadily rising. UTC Foods, which is working closely with adzuki producers in Pingtung, has attained orders from the United States, Canada and elsewhere, as well as from the international coffee chain Starbucks, which is supplying its locations in the Asia-Pacific region with beverages made from adzuki beans and green-tea powder.

The district of Daliao in Kaohsiung broke new ground last year by releasing unprocessed adzuki beans, marketed under the name “Red Diamond.” These well-received beans have attained Traceable Agricultural Product certification from the COA. Daliao’s farmers’ association says that it can sell at least 10 tons a year on the domestic market and that it is in discussions to export to Brunei.

Why are the locally produced beans better than the imported stuff?

Chen explains that the locally grown adzuki beans are larger than the imported varieties, and their smooth mouthfeel and fine consistency are also clearly superior to the harder and grittier imported beans. What’s more, the locally produced beans have a naturally sweet flavor without the need for a sweetener.

To sample the sweet taste of joy, you needn’t go far: Taiwan-grown adzuki beans are right at hand.

X 使用【台灣光華雜誌】APP!
更快速更方便!