Research by four students from Tainan County's National Hsin Hua Industrial Vocational High School has shown that steeping fresh almond powder in boiling water is the method most likely to retain its healthful properties and reduce the danger from hydrocyanic acid.
The project has garnered the students first place in the National High School and Vocational School Science Fair's vocational school chemical engineering, health and environmental division.
About six months ago, a teacher at the school who had drunk a beverage prepared from almond powder purchased in the market experienced a headache, dizziness and stomach pain. He feared that he had been sold another substance in place of the almond powder, and rushed back to the market stall to return the goods. The incident inspired the four girls, all second-year students—twins Chao Chih-chun and Chao Chih-han, Wu Hsiao-han and Luo Yi-nong—to investigate the toxicity of almond powder.
Chao Ming-liang, a chemical engineering teacher at the school, said the primary component of almond powder is amygdalin, which can act to fight inflammation and reduce pain. However, when almond powder is steeped in water, a hydrolysis reaction is possible, which produces toxic hydrocyanic acid.
Although the amount of this acid produced is still well within the safe range, people who are more sensitive to this substance, or young children, may be prone to angina, stomach pain, dizziness and other symptoms if they consume it.
To find out exactly what had caused their teacher's symptoms, the four girls went to the night market, the traditional market and a supermarket to purchase three types of almond powder, and then prepared them by dissolving them in water at 60, 80 and 100 degrees Celsius.
High performance liquid chromatography was used to analyze the samples, in hopes of finding the temperature that impacted the amounts of hydrocyanic acid and amygdalin. The results indicated that almond powder dissolved at 100 C and mixed for five to six minutes in a well-ventilated location before drinking retained a good content of amygdalin while reducing the harmful effects of hydrocyanic acid, thus maximizing the health benefits of the drink.
The girls' findings also include that almond powder dissolved in 80-degree water had nearly 50 percent less amygdalin than that dissolved at 100 degrees. The powder placed in 60-degree water retained less than 40 percent of the amygdalin seen in the 100-degree sample. The more amygdalin retained, the less hydrocyanic acid was found in the end product.
Yang Hui-chang, head of the Chinese Medicine Department at Chimei Medical Center, said almond powder is listed in the “Bencao Gangmu” (a Chinese materia medica work written by Li Shizhen in the Ming dynasty) as being slightly toxic.
Most almond powder sold on the market to be dissolved in water contains a high proportion of sweet almond (southern almonds), which contains very little hydrocyanic acid. The relatively low 10-percent proportion of bitter almond means that the acid likely did not cause the symptoms experienced by the teacher.
Yang added that bitter almond (northern almond) is used for medicine, and is likely to cause stomach pain, headache, angina and other symptoms, and even death in serious cases, if it is consumed without being parched or stewed.
(This article originally appeared in The Liberty Times Aug. 5.)