Page 47 - FoodFocusThailand No.182 May 2021

STRONG QC & QA

ก�รปลูกอย่�งแพื้ร่หล�ย โดยแนัะนัำ�วิ่�ค้่�สำ�รละล�ย รููปที่่� 2 ภ�พื้บรรย�ก�ศก�รฝึึกอบรม
เชิงปฏิิบัติก�ร “หลักก�รผัลิตผัักไฮโดร-
ธ�ตุอ�ห�ร หร้อค้่� EC ในัระหวิ่�งก�รปลูกไม่ค้วิรเกินั 1.4 โพื้นัิกสำ์ทีี�ดีและปลอดภัย” เม้�อวิันัทีี� 25
mS/cm และเกษตรกรค้วิรลดก�รเติมสำ�รละล�ยธ�ตุอ�ห�ร เมษ�ยนั 2562 ณ มห�วิิทีย�ลัย
เกษตรศ�สำตร์ วิิทีย�เขตกำ�แพื้งแสำนั
หร้อมีก�รแทีนัทีี�สำ�รละล�ยธ�ตุอ�ห�รด้วิยนัำ��เปล่�ก่อนั Figure 2 Workshop on “Principles
for Good and Safe Hydroponic
เก็บเกี�ยวิ 2-4 วิันั โดยห�กทีำ�ต�มวิิธีก�รนัี�จัะสำ�ม�รถ Vegetable Production” (April 25,
2019) at Kasetsart University,
ลดปริม�ณไนัเตรทีสำะสำมได้ม�กกวิ่�ร้อยละ 60 ในัผัักทีุกชนัิด Kamphaeng Saen Campus
และในัทีุกฤดูก�ลของก�รปลูก
สำุดที้�ยนัี� “ก�รบริโภค้ผัักปลอดภัยให้ได้ประโยชนั์ ไม่ค้วิร รููปที่่� 3 ทีีมนัักวิิจััยลงพื้้�นัทีี�สำำ�รวิจัและตรวิจัวิัดปริม�ณ
สำ�รไนัเตรทีตกค้้�งในัผัักทีี�ฟ�ร์มของเกษตรกร
บริโภค้ผัักชนัิดใดชนัิดหนั่�งเป็นัประจัำ� ค้วิรกินัผัักให้ Figure 3 Our researcher team surveyed and
หล�กหล�ยชนัิด จั�กหล�ยแหล่งปลูก สำับเปลี�ยนัหมุนัเวิียนั measured the residual nitrate content in
hydroponic solution at hydroponic farm in
กันัไป เพื้้�อได้รับประโยชนั์ที�งด้�นัโภชนั�ก�รค้รบถ้วินั” Thailand

Recently, there have been consumer concerns about the safety of consuming hydroponic vegetables
due to the reports on the detection of various residue. Nitrate residue in hydroponic vegetables have raised
an important concern because high level of nitrate residue could possibly convert to nitrite in human body
caused an adverse health effects such as methemoglobinemia and carcinogenesis.
Thus, the level of accumulated nitrate in dietary vegetables coral, butterhead) with low nitrate residue, the recommendation of the
should be precisely monitored and controlled. The project EC for hydroponic solution during plantation should not exceed
“Development of hydroponic vegetables production model to 1.4 mS/cm. Importantly, the replacement of nutrient solution with water
promote consumption of safe vegetable” financially supported at least 2-4 days before harvesting is highly recommended due to this
by Thai Health Promotion Foundation aims to develop the production could significantly reduce nitrate contents up to 60% for all crops grown
model to plant hydroponic vegetables in Thailand. The project in every growing seasons.
director is Assistant Professor Dr.Warapa Mahakarnjanakul teamed Lastly, it is recommended to consume a variety types of vegetables
up with Assistant Professor Dr.Kanithaporn Vangnai, Assistant on a regular basis from various planting sources to gain the best benefit
Professor Dr.Kriskamol Na Jom, and Assistant Professor of consuming vegetables.
Dr.Kullanart Tongkhao from Department of Food Science and
Technology, Faculty of Agro-Industry, Kasetsart University together
with Associate Professor Dr.Thammasak Thongket and
Dr.Roongnapa Korpraditskul who are the researchers of Department
of Horticulture, Faculty of Agriculture, Kamphaeng Saen
Campus
Nitrate Residue in Hydroponic Vegetables…How
to Plant and Consume Safely? Nitrate is a form of nitrogen
that is a key need for successful plant growth. Introduction of high
quantities of nitrate fertilizer can also lead to accumulation of nitrate
in vegetables, especially hydroponic vegetables. According to EU
legislation, maximum levels for nitrate in vegetables have been set
up at 3,000-4,500 ppm depended on vegetable type and season.
Although, no epidemiological studies reported the association
between the intake of nitrate from diet or drinking water and the
increase the risk of cancers, However, too much nitrate intake may
associate with fatal growth restriction. An acceptable daily Intake
(ADI) for nitrate of 3.7 mg/kg bw/day, equivalent to 222 mg nitrate
per day for a 60 kg adult was established by the Joint FAO/WHO
Expert Committee on Food Additives (JECFA) since 2002. As part
of a healthy diet in low fat, sugars and sodium, WHO suggests
consuming al least 400 g of fruits and vegetables daily to improve
overall health and reduce the risk of certain diseases. As a
conservative base case, a person eating 400 g of mixed vegetables
at typical median nitrate concentration levels would an average
receive a dietary exposure to nitrate of 150 mg/day which is still
lower than ADI level considered as safe for consumer.
High accumulation of nitrate in vegetables could cause by
many reasons during plantation such as high temperature and light
intensity, climate condition, drought, the high supply of nitrate
fertilizer which could be measured by solution electrical conductivity
(EC) in hydroponic solution. According to the research output from
our project to plant lettuce vegetables (e.g. green oak, red oak, red
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