Spinach

When you watch the cartoon "Popeye the Sailor", the protagonist Popeye always consume a can of spinach, thus become very strong. Although this cartoon exaggerates the health effect of this vegetable, it still has giant nutritional value in the real world. Spinach contains a lot of iron ion when compare to other vegetables, very benefit to those suffer from anemia or after menstruation. In Chinese cuisine, spinach is stir fry with garlic or other meat like beef, pork etc. While in Western cuisine, spinach are used for pasta, bake with cheese, salad etc.

Spinach divided into two main type, which is bunching spinach and baby leaf spinach. Bunching spinach is spinach specialized in harvest them  in mature stage for bunching purpose, while baby leaf mainly harvest in baby stage

There are three types of Spinach seeds in vegetable seeds shop. The first type of seeds is with a sharp hard shell, farmer need to squeeze the shell in order to let internal area absorb water. The second type is unshelled, it will be convenient for farmer to grow but bear some risk like eaten by insect and rats. The third type is unshelled but treated with pesticide, so those seeds appear in pink color as a warning pigment and it is the most common form found in seed company.

Our farm does not encourage the use of chemicals, so it is very difficult for Mr. Wong to find untreated seeds as they are limited in the past. Fortunately, untreated seeds become popular in recent years due to the necessary of organic farms. Mr. Wong will buy those unshelled, untreated seeds to start the young plants.

Mr. Wong usually starts his sowing at the start of December. Those spinach seeds spout rapidly, and seedlings can be transplant after one month in the seedling trays. Many holiday farmers buy seedling from him and they harvest them after 2 months later.

I introduced Australian baby leaf spinach in December, 2017. I got the seeds during my studies in Australia, and brought back to Hong Kong for a trial. The seeds were sowed at the land directly around start of December. The baby spinach became large enough to harvest in January, 2018. I harvested some baby spinach for salad and harvested some for local artist Wong Wing Fung. She used my baby spinach to make French quiche which is delicious.

 

Many neighbour farmers asked me how come my baby spinach looks different than their oriental spinach as they haven't seen it before, they also asked how come my baby spinach can diectly sowed intensively as they normally used seedlings from Mr Wong and grew them as 4 x 12 matrix in their land.

The root of spinach in our farm is bright red, thicker than those in supermarket. Even the area of leafs are larger when compare to other spinach in Hong Kong.

For the food chemistry in Spinach, folate can be found within the plant.

Folate as a important vitamin in the body. Folate (Vitamin B9) is a very important vitamin, which prevent some severe disease like neural tube defects (NTDs), spina bafida, anencephaly in infants, megaloblastic anemia, cardiovascular disease, certain cancers in adult etc.(1)

Mechanism of action for folate in maintaining metabolism for body. Folate acts as co-factors in the cell cycle by carry one carbon unit in various cellular functions(1). They involved in the DNA biosynthesis cycle, as well as methylation cycles. Vast numbers of metabolites are essential key for normal cell function(1). Human and animals cannot synthesize the folate – “de novo” within their bodies, which indicate they relied on the intake of dietary sources which contains vegetable(1).

Folate is extremely useful on management of type 2 diabetes mellitus. A study recruited post-menopausal Korean woman aged 56-74 years who suffered from diabetes mellitus with amenorrhea for over 24 months, some participant take folic acid while the rest take placebo (2). Blood sample were draw from their body for analysis of blood glucose level (2). The trial group woman took 800 µg of folic acid daily, and they showed improved serum Hcys, folate, and vitamin B₁₂ levels as well as lipid parameters, including lower LDL-C (Low density lipoprotein) level as well as LDL-C/HDL-C and TC/HDL-C ratios.(2) Those effect contribute to the prophylaxis of atherosclerosis as they have higher risk when compare to normal person (2).

Different spinach varieties contain different level of folate in the plant. A study collected 67 varieties of spinach from different locations, 57 accessions collected from United State Department of Agriculture (USDA) – Agricultural research Service (ARS), Germplasm Resources Information Network (GRAIN), 11 accessions came from Asian Vegetable Research and Development Center (AVRDC) Vegetable Genetic Resources Information System (AVGRIS) (3).

Then they germinated 20 seeds of each accession (3). They rinsed the seeds with deionized water, then sterilized the surface by 0.07% sodium hypochlorite (NaOCl) for half hour (30 minutes), and drained them finally (3). They placed the seeds in aerated deionized water and soaked it overnight (3). They discarded the water and place each seed in black plastic pots with volume 15 x 15 x 15 cm3, filled with a 1:1:1 (v/v/v) mixture of peat, perlite and vermiculite (3).

After they germinated, they thinned out 8 seedlings from the pot, which left only 12 healthy seedling of each accession within the pot (3). They placed the pot within growth chamber with changing position every third day (3). Those plant were maintained on a 12 hour photoperiod of 200 micromole m -2 s -1 photosynthetically active radiation (incandescent and fluorescent lamps), with a 22 + - 0.5 Celsius degree, 18 +- 0.5 Celsius degree day/ night temperature regime (3). Some of those accessions like TOT 6497, PI 175313 and PI 604785 etc, were grown in 9 hour photoperiod to avoid premature bolting (3). The relative humidity was controlled within 50 +- 5% (3). They irrigated the plant by deionized water at first until emergence, then they irrigated them with modified nutrients solution (Contains 1.43 mM NH4NO3, 1.00mM CaCl2, 1.64 mM MgSO4, 0.32mM NaH2PO4, 1.32 mM K2SO4, 5.0 micro molar of MnCl2, 0.2 micro molar CuSO4, 0.075 micro molar (NH4)6 Mo7O24, 1.90 micro molar of H3BO3, 20.0 micro molar of Fe-HEDTA, 1.0 micro molar of ZnSO4, and 0.1 micro molar NiSO4), before applied to those seedlings, the pH was adjusted to 5.5 with 0.1 M NaOH or 0.1 M HCl, depends on the acidity/Basicity of the solution (3).

They sampled the plants at 5 weeks of age, with 5 – 6 fully expanded leaves (3). Those plants was excised 0.5 cm above the base (3). The areal part of harvested material included both mature and immature leaves (Petioles and leaf blades), they weighted the fresh weight of those leafs (3). They cut six plants of each accession and combined together to form composite sample, which represented accession for folate analysis (3).

Those samples are protected from oxidation by storing within argon gas, yellow fluorescence, cooling on ice after heating (3). They grinded 5 grams (fresh weight) of the sample into fine powder in liquid nitrogen (3). Those powder was transferred to a 50mL plastic centrifuge tubes, then they added 15 mL of the extraction buffer (0.1 M phosphate buffer contain 1.0% of L(+)-ascorbic acid (w/v) and 0.1% BAL (v/v) at pH 6.5 which freshly prepared), flushed with argon gas and capped (3).

They placed them at 100 Celsius degree for 10 minutes to break down the tissue and cool it by ice (3). Then they centrifuged them for 20 minutes at 4 Celsius degree (3).

For the results, it shows that TOT7337-B contain the largest amount of folic acid.(3)
Discovery on those high and low folate spinach accessions may understand more on the molecular basis of folate variation and improve the nutrients in spinach (3).

1.     Pufulete M, Emery PW, Sanders TAB. Folate, DNA methylation and colo-rectal cancer. The Proceedings of the Nutrition Society. 2003;62(2):437-45.

2.     Vijayakumar A, Kim E-k, Kim H, Choi YJ, Huh KB, Chang N. Effects of folic acid supplementation on serum homocysteine levels, lipid profiles, and vascular parameters in post-menopausal Korean women with type 2 diabetes mellitus. Nutrition Research and Practice. 2017;11(4):327-33.

3.     Shohag MJI, Wei Y-y, Yu N, Zhang J, Wang K, Patring J, et al. Natural Variation of Folate Content and Composition in Spinach (Spinacia oleracea) Germplasm. Journal of Agricultural and Food Chemistry. 2011;59(23):12520-6.



Figure 1: Baby spinach trialing in the farm, they are growing steadily































Figure 2: Baby spinach seedlings perform well under cold weather in Ma On Shan farm









 



Figure 3: Baby spinach ready for harvest







Figure 4: Close up of baby spinach





  




Figure 5: Baby spinach look fantastic



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Figure 6: Baby Spinach harvest

Figure 7: Cleaning baby spinach to prepare salad 

Figure 8: Baby spinach salad is awesome

Figure 9: Baby spinach quiche made by Wong Wing Fung



Figure 10: Oriental Spinach seedlings in punnets grown by Uncle Kwong for city farmers in Natural organic farm, many Hongkongers like traditional Chinese or Japanese spinach for Guangdong dishes rather than western baby leaf spinach