Spinach (Spinacia oleracea L.)
(fresh or processed leaves; family Amaranthaceae)
Spinach is one of the most recognizable leafy vegetables, known for its fleshy, deep-green leaves and a delicate flavor with a slightly ferrous note. This annual herbaceous plant, belonging to the family Amaranthaceae and originally from Southwestern Asia, became deeply rooted in Mediterranean lands, where it gradually earned a stable place in culinary traditions. Its leaves, smooth or gently crinkled depending on the variety, range from rounded to more elongated shapes, and their texture changes with plant maturity: tender and soft in baby forms, more structured and resilient as the plant reaches full growth.
Spinach thrives in cool climates, fertile soil rich in organic matter, and consistent but moderate watering. Once harvested, the leaves preserve their quality only with gentle handling, as they bruise easily. When enjoyed raw, spinach retains its fresh vegetal aroma and natural abundance of water, fiber, and micronutrients; when cooked briefly, it reveals a silkier texture and a more pronounced fragrance. Within its tissues are compounds such as carotenoids, folic acid, iron, magnesium, and ample chlorophyll, responsible for its vivid green hue.
Appearing in salads, fillings, soups, savory pies, and classic recipes, spinach stands out for its remarkable versatility: from Mediterranean kitchens to Middle Eastern and Asian traditions, it crosses cuisines with effortless harmony. Although it naturally contains oxalates, which can limit the absorption of some minerals, spinach remains widely appreciated as an ingredient that symbolizes simplicity, quick growth, and ease of use. Whenever conditions are favorable, it continues to be a favorite choice for those seeking something fresh, light, and deeply connected to cultural memory.
Botanical classification
Climate
Spinach prefers a cool, temperate climate, with mild springs and autumns that support rapid and continuous growth. Excessively high temperatures quickly lead to bolting, reducing leaf quality, while moderate cold is fairly well tolerated, especially in more rustic varieties.
Exposure
The ideal exposure is full sun during the cooler seasons, in order to promote good photosynthesis and tender, well-developed leaves. In warmer climates or towards late spring, light shading during the central hours of the day can help to limit heat stress and delay bolting.
Soil
Spinach grows best in medium-textured, deep, well-drained soils that are rich in organic matter and have a neutral to slightly alkaline pH. A soft, well-worked soil supports root development and rapid growth of the aerial parts. Waterlogging should be avoided, as it can cause root rot and slow down growth.
Irrigation
Irrigation should be regular and moderate, keeping the soil consistently moist but not saturated. Sudden water shortages can make the leaves tougher and encourage bolting, while excessive water increases the risk of fungal diseases. Light mulching helps to reduce evaporation and keep soil moisture more stable.
Temperature
The optimal temperature range for germination and development is generally between 10 and 20 °C. Prolonged high temperatures, especially above 22–24 °C, stimulate flower stalk formation at the expense of leaves. By contrast, low temperatures within certain limits are tolerated, allowing autumn–winter cultivation in many areas.
Fertilization
Fertilization is based on a good supply of well-matured organic matter before sowing or transplanting, which improves soil structure and fertility. Because spinach grows quickly and is mainly a leaf crop, nitrogen plays an important role, but it must be applied carefully to avoid excessive accumulation and overly tender, disease-prone foliage. Phosphorus and potassium help maintain good nutritional balance and plant robustness.
Crop care
Crop care includes weed control, which is particularly important in the early stages of development, using light hoeing or mulching. Keeping the soil surface loose improves aeration and drainage. Regular monitoring allows early detection of pests or fungal diseases, so that timely interventions can limit damage to leaf production.
Harvest
Spinach can be harvested in two ways: by cutting the entire rosette at the base once the leaves have reached the desired size, or by picking the outer leaves as they grow, leaving the centre to produce new foliage. It is important to harvest before the plants start to bolt, as leaves then become tougher and of lower quality.
Propagation
Propagation is by seed, usually by direct sowing in the field or in well-prepared beds. Seeds are sown in rows or broadcast, and the soil is kept moist until germination. Once seedlings have emerged, thinning is carried out to give each plant enough space to develop, thus obtaining larger rosettes and higher quality leaves.
Indicative nutrition values (per 100 g raw; typical averages)
• Energy: ~23 kcal
• Carbohydrates: ~3.6 g (sugars ~0.4 g)
• Dietary fiber: ~2.2 g
• Protein: ~2.9 g
• Fat: ~0.4 g — SFA negligible; MUFA/PUFA negligible
• Sodium: ~70–80 mg (natural)
• Potassium: ~550–600 mg • Magnesium: ~75–80 mg • Calcium: ~90–120 mg • Iron (non-heme): ~2–3 mg
• Vitamins: very high K1, folate, vitamin A (as β-carotene), vitamin C (~25–30 mg)
Key constituents
• Chlorophylls a/b; carotenoids (β-carotene, lutein/zeaxanthin).
• Folate, vitamin K1 (phylloquinone), vitamin C.
• Nitrates (natural; vary by season/cultivation).
• Oxalates (soluble/insoluble) that chelate Ca/Fe and limit bioavailability.
• Cell-wall polysaccharides (cellulose/hemicelluloses/pectins), organic acids.
Production process
• Short-cycle cultivation; manage nitrogen/irrigation to control nitrates.
• Harvest mechanical/manual → sorting, trimming, multi-wash.
• RTE salads: gentle drying, MAP packing; frozen: quick blanch, cool, IQF.
• Full traceability and controls under GMP/HACCP.
Physical properties
• pH ~5.5–6.8; very high aw.
• Color: vivid green → shifts to olive when acidified or overcooked (chlorophyll → pheophytin).
• Texture: tender raw; melting texture when cooked, with high purge.
Sensory & technological properties
• Short cooks (steam/sauté) preserve color and vitamin C; blanching lowers oxalates and microbial load.
• Acidity (lemon/vinegar) brightens flavor but speeds color shift; baking soda is discouraged (nutrient/texture loss).
• Excellent binder in fillings/gnocchi/patties; purée for sauces/creams; strong synergy with dairy, eggs, and warm spices.
Food applications
• Raw: salads, bowls, sandwiches.
• Cooked: sautéed/steamed, soups, fillings (pasta, pies), bakes, frittatas, savory smoothies.
• Industry: RTE salad mixes, single-serve frozen portions, creams and bases for ready meals.
Nutrition & health
Spinach is low-calorie and micronutrient-dense (K1, folate, pro-vitamin A carotenoids, vitamin C), with trivial fat and SFA. Iron is mainly non-heme and its bioavailability is limited by oxalates; it improves with vitamin C (e.g., citrus, peppers) and by avoiding excessive calcium in the same meal. Calcium absorption from spinach is likewise reduced by oxalate complexation.
Natural nitrates may support endothelial function (via NO) in healthy adults; however, for infants <1 year, avoid frequent servings of high-nitrate vegetables and long hot holding, due to nitrite/methemoglobinemia risk—cool quickly and refrigerate.
For those with calcium-oxalate kidney stones or IBS (insoluble-fiber sensitivity), tailor portion and frequency with a clinician. On warfarin, keep vitamin K intake consistent (do not eliminate it).
Portion note: as a side, 120–200 g cooked (≈ 400–600 g raw before wilting); for raw salads, 50–100 g per serving.
Quality & specifications (typical topics)
• Appearance: intact, turgid green leaves; free from yellowing, thick stems, soil/grit.
• Residues: pesticides ≤ MRL; metals within limits; nitrates within legal/spec limits.
• Microbiology: low counts; pathogens absent/25 g (RTE focus on E. coli, Salmonella, Listeria).
• Physicochemical: high moisture, pH, sand/grit; for frozen, verify blanch/IQF parameters.
Storage & shelf-life
• Fresh: 0–4 °C, high RH, away from ethylene; use within 3–7 days (RTE per date code).
• Frozen: ≤ −18 °C; do not refreeze after thawing.
• Cooked: chill quickly, store at ≤4 °C, consume within 48 h; avoid prolonged warm holding (nitrites).
Safety & regulatory
• Vegetable subject to marketing and hygiene standards; RTE salads require stringent washing, MAP, and cold-chain control.
• Nitrates: legal limits for spinach (fresh/baby/frozen); field and lot testing.
• Allergens: none intrinsic; manage cross-contact in plant.
Labeling
• Name: “spinach” (or “baby spinach” for young leaves); RTE packs “washed/ready to eat”.
• Origin, class, size (where applicable), storage temperature, date code; for frozen/processed, full ingredient list (salt, condiments).
Troubleshooting
• Sliminess → cold-chain break or excess moisture → improve drainage and maintain 0–4 °C.
• Gritty mouthfeel → insufficient washing → increase wash stages/turbulence and sieving.
• Olive color when cooked → acidity/overcook → cook briefly and hot; add salt/acid at the end.
• Watery prep → inadequate draining → squeeze or reduce formulation water.
• Strong bitter/metallic → older leaves/water stress → prefer baby or spring/autumn crops.
INCI functions (cosmetics)
• Spinacia Oleracea Leaf Extract: antioxidant, skin-conditioning in serums/creams.
• Spinacia Oleracea Seed Oil (rare): light emollient. Use per cosmetic regs and tolerability.
Conclusion
Spinach is a versatile, micronutrient-dense leafy vegetable. Optimal results come from very fresh raw material, short cooking, careful water management, and attention to nitrates/oxalates for sensitive groups.
Mini-glossary
• SFA: saturated fatty acids — keep overall intake low; spinach provides negligible amounts.
• Bioavailability: fraction of a nutrient that is absorbed and utilized.
• Oxalates: chelators that reduce Ca/Fe absorption and may contribute to stones in predisposed individuals.
• Nitrates/Nitrites: natural salts; nitrites may form during prolonged warm holding.
• Pheophytin: chlorophyll degradation product causing olive hue.
• RTE / MAP / IQF: ready to eat / modified atmosphere packaging / individually quick frozen.
• MRL: maximum residue limits.
• GMP/HACCP: good manufacturing practices / hazard analysis and critical control points.
Studies
It is rich in minerals, vitamins, carotenoids, polysaccharides and has been used by traditional medicine as an antioxidant therapeutic agent (1).
Compared to other plants, the consumption of spinach remains rather low despite the fact that he has many positive activities for human health such as (2):
- prevent macromolecular oxidative damage
- modulate the expression and activity of genes involved in metabolism, with antioxidant, anti-inflammatory activity
- curb food intake by inducing secretion of satiety hormones (anti-obesity)
Among the most interesting components present in spinach are some flavonoids that exert antimutagenic properties (3):
- spinacetin
- 5,3',4'-trihydroxy-3-methoxy-6,7-methylenedioxyflavone
- protocatechuic acid
- ferulic acid
- coumaric acid
Based on the results of this study, it was deduced that extracts of spinach leaves exert antimicrobial activity both by inducing mutations in the DNA and by causing interruptions of the cell wall of the bacteria (4) .
Spinach studies
References__________________________________________
(1) Mzoughi Z, Souid G, Timoumi R, Le Cerf D, Majdoub H. Partial characterization of the edible Spinacia oleracea polysaccharides: Cytoprotective and antioxidant potentials against Cd induced toxicity in HCT116 and HEK293 cells. Int J Biol Macromol. 2019 Sep 1;136:332-340. doi: 10.1016/j.ijbiomac.2019.06.089.
Ko SH, Park JH, Kim SY, Lee SW, Chun SS, Park E. Antioxidant Effects of Spinach (Spinacia oleracea L.) Supplementation in Hyperlipidemic Rats. Prev Nutr Food Sci. 2014 Jan;19(1):19-26. doi: 10.3746/pnf.2014.19.1.019.
Abstract. Increased consumption of fresh vegetables that are high in polyphenols has been associated with a reduced risk of oxidative stress-induced disease. The present study aimed to evaluate the antioxidant effects of spinach in vitro and in vivo in hyperlipidemic rats. For measurement of in vitro antioxidant activity, spinach was subjected to hot water extraction (WE) or ethanol extraction (EE) and examined for total polyphenol content (TPC), oxygen radical absorbance capacity (ORAC), cellular antioxidant activity (CAA), and antigenotoxic activity. The in vivo antioxidant activity of spinach was assessed using blood and liver lipid profiles and antioxidant status in rats fed a high fat-cholesterol diet (HFCD) for 6 weeks. The TPC of WE and EE were shown as 1.5±0.0 and 0.5±0.0 mg GAE/g, respectively. Increasing the concentration of the extracts resulted in increased ORAC value, CAA, and antigenotoxic activity for all extracts tested. HFCD-fed rats displayed hyperlipidemia and increased oxidative stress, as indicated by a significant rise in blood and liver lipid profiles, an increase in plasma conjugated diene concentration, an increase in liver thiobarbituric acid reactive substances (TBARS) level, and a significant decrease in manganese superoxide dismutase (Mn-SOD) activity compared with rats fed normal diet. However, administration of 5% spinach showed a beneficial effect in HFCD rats, as indicated by decreased liver TBARS level and DNA damage in leukocyte and increased plasma conjugated dienes and Mn-SOD activity. Thus, the antioxidant activity of spinach may be an effective way to ameliorate high fat and cholesterol diet-induced oxidative stress.
(2) Roberts JL, Moreau R. Functional properties of spinach (Spinacia oleracea L.) phytochemicals and bioactives. Food Funct. 2016 Aug 10;7(8):3337-53. doi: 10.1039/c6fo00051g.
Abstract. Overwhelming evidence indicates that diets rich in fruits and vegetables are protective against common chronic diseases, such as cancer, obesity and cardiovascular disease. Leafy green vegetables, in particular, are recognized as having substantial health-promoting activities that are attributed to the functional properties of their nutrients and non-essential chemical compounds. Spinach (Spinacia oleracea L.) is widely regarded as a functional food due to its diverse nutritional composition, which includes vitamins and minerals, and to its phytochemicals and bioactives that promote health beyond basic nutrition. Spinach-derived phytochemicals and bioactives are able to (i) scavenge reactive oxygen species and prevent macromolecular oxidative damage, (ii) modulate expression and activity of genes involved in metabolism, proliferation, inflammation, and antioxidant defence, and (iii) curb food intake by inducing secretion of satiety hormones. These biological activities contribute to the anti-cancer, anti-obesity, hypoglycemic, and hypolipidemic properties of spinach. Despite these valuable attributes, spinach consumption remains low in comparison to other leafy green vegetables. This review examines the functional properties of spinach in cell culture, animals and humans with a focus on the molecular mechanisms by which spinach-derived non-essential phytochemicals and bioactives, such as glycolipids and thylakoids, impart their health benefits.
(3) Singh A, Singh P, Kumar B, Kumar S, Dev K, Maurya R. Detection of flavonoids from Spinacia oleracea leaves using HPLC-ESI-QTOF-MS/MS and UPLC-QqQLIT-MS/MS techniques. Nat Prod Res. 2019 Aug;33(15):2253-2256. doi: 10.1080/14786419.2018.1489395.
Abstract. Spinacia oleracea L. (Spinach) is a leafy vegetable which is considered to have a high nutritional value. Flavonoids in spinach were reported to act as antimutagenic property. Rapid detection of these flavonoids in Spinach was achieved by using HPLC-ESI-QTOF-MS/MS. Thirty six compounds were tentatively identified based on their retention times, accurate mass and MS/MS spectra. The fragmentation patterns of known compounds were applied to elucidate the structure of their corresponding derivatives having the same basic skeleton. Out of thirty six peaks, three peaks were assigned as patuletin and six peaks were assigned as spinacetin derivatives. Twelve compounds were first time identified following the fragmentation pattern of known compounds. Five of the identified compounds i.e., spinacetin, 5,3',4'-trihydroxy-3-methoxy-6,7-methylenedioxyflavone, protocatechuic acid, ferulic acid and coumaric acid were simultaneously quantified in spinach leaves by a validated UPLC-ESI-MS/MS method under MRM mode.
(4) Altemimi A, Lakhssassi N, Abu-Ghazaleh A, Lightfoot DA. Evaluation of the antimicrobial activities of ultrasonicated spinach leaf extracts using RAPD markers and electron microscopy. Arch Microbiol. 2017 Dec;199(10):1417-1429. doi: 10.1007/s00203-017-1418-6.
Abstract. Spinach (Spinacia oleracea L.) leaves represent an important dietary source of nutrients, antioxidants and antimicrobials. As such, spinach leaves play an important role in health and have been used in the treatment of human diseases since ancient times. Here, the aims were to optimize the extraction methods for recovering antimicrobial substances of spinach leaves, determine the minimum inhibitory concentrations (MICs) of the antimicrobial substances against Escherichia coli and Staphylococcus aureus and, finally, evaluate the effects of spinach leaves' antimicrobials on bacterial DNA using central composite face-centered methods. The effect of the extracts on both Gram-positive and Gram-negative bacterial models was examined by scanning electron microscopy (SEM) and random amplification of polymorphic (bacterial) DNA (RAPD). The optimal extraction conditions were at 45 °C, ultrasound power of 44% and an extraction time of 23 min. The spinach extracts exhibited antimicrobial activities against both bacteria with MICs in the 60-100 mg/ml range. Interestingly, SEM showed that the treated bacterial cells appear damaged with a reduction in cell number. RAPD analysis of genomic DNA showed that the number and sizes of amplicons were decreased by treatments. Based on these results, it was inferred that spinach leaf extracts exert bactericidal activities by both inducing mutations in DNA and causing cell wall disruptions.
Spinach 
Chlorophyll
