Review

Thaibonnet rice (Oryza sativa L., indica type, Long B)

Description

Thaibonnet rice is a Long B (indica-type) cultivar of Oryza sativa L., characterized by long, very slender grains with a crystalline (vitreous) structure. Although its name suggests an Asian origin, Thaibonnet is a Californian-bred variety later introduced and registered in Italy, where it has been cultivated since the late 1980s and early 1990s. It is now widely used in Italian rice production, especially for applications that require separate grains and stable texture after cooking (food service, ready dishes, rice salads).

Botanically, Thaibonnet belongs to the indica group and falls into the commercial class “Long B”. The dehulled and milled kernel is narrow, elongated and needle-shaped, with a high length-to-width ratio and a vitreous, non-chalky endosperm. The cultivar is typically offered as white Long B rice and very often as parboiled Thaibonnet, obtained by hydrothermal treatment of paddy rice (soaking, steaming, re-drying) before milling. This process compacts the starch, improves mechanical resistance of the grain and favours the migration of some B vitamins and minerals from the bran layers towards the inner endosperm.

In Italy and other markets, Thaibonnet is positioned as a technical long-grain rice for cold dishes, pilaf, side dishes and catering, where resistance to overcooking, low stickiness and good performance under reheating are particularly important.

Botanical classification
Common name: Thaibonnet rice (long-grain rice)
Clade: Angiosperms
Order: Poales
Family: Poaceae
Genus: Oryza
Species: Oryza sativa L.

Cultivation and growth conditions

Climate
Thaibonnet rice is a long-grain rice cultivar suited to warm–temperate climates, with hot summers and abundant water availability during the growing cycle. It requires a growing season free from frost, with relatively high average temperatures during tillering, stem elongation and ripening. It is sensitive to low temperatures during germination and flowering, which can reduce grain set.

Exposure
Like other rice varieties, it needs full sunlight to ensure efficient photosynthesis and good panicle formation. Prolonged shading or competition from tall vegetation along paddy borders reduces yield and may favour stronger development of weeds.

Soil
Thaibonnet rice is usually grown on alluvial or flat soils suitable for flooding. It prefers clay or clay–loam soils able to retain water at the surface, with a good level of organic matter and nutrients. Very sandy, highly permeable soils are unfavourable because they do not allow a stable water layer to be maintained. The optimal pH ranges from slightly acidic to neutral or mildly alkaline.

Irrigation
The crop is managed as a typical flooded paddy rice, sometimes with false sowing followed by flooding. It is essential to maintain a constant water layer (usually a few centimetres) for most of the cycle, adjusting water depth in the different phases (pre-emergence, tillering, stem elongation, ripening). Excessive water level fluctuations or unplanned dry periods cause stress and can increase weed pressure.

Temperature
Optimal temperatures for germination are generally above 12–13 °C, while for vegetative development and flowering mean values between about 20 and 30 °C are preferable. Too low temperatures during flowering impair fertilization, whereas prolonged heat stress, especially with strong radiation and dry winds, can cause grain scorching and quality loss.

Fertilization
Thaibonnet rice requires a balanced supply of nitrogen (N), phosphorus (P) and potassium (K).

• Nitrogen should be split (for example pre-sowing/pre-flooding and topdressings) to promote good tillering without excessive lodging.

• Phosphorus is important in the early stages for root system development.

• Potassium contributes to lodging resistance and improves several grain quality parameters.

Excessive nitrogen promotes fungal diseases, increases the risk of lodging and can raise susceptibility to insect attacks.

Crop care
Main operations include:

• management of weeds, through crop rotation, false sowing, mechanical control and/or targeted chemical control;

• careful regulation of water levels to contain typical paddy weeds and reduce water stress;

• possible control of diseases (e.g. rice blast) and pests using integrated protection techniques;

• accurate land levelling, essential for uniform flooding.

Proper sowing density and balanced nutrition help reduce competition and lodging.

Harvesting
Thaibonnet rice is harvested when grain ripening is uniform and the moisture content is suitable for combine harvesting and subsequent drying. Excessive delay in harvesting can result in lodging, grain loss and quality reduction (breakage, chalkiness). After harvest, the product is dried to a moisture level compatible with safe storage and further milling processes.

Propagation
The cultivar is propagated using certified seed, produced in varietal seed multiplication plots to maintain the genetic characteristics of Thaibonnet (long grain, cooking performance, etc.). On farm, sowing in paddy fields is carried out (broadcast or in rows, on dry or flooded soil depending on the technique), using a seed rate appropriate to the target plant density and field conditions.

Indicative nutritional values per 100 g

(Thaibonnet parboiled, uncooked – approximate ranges)

• Energy: ~ 360–375 kcal

• Water: ~ 8–10 g

• Total carbohydrates: ~ 72–82 g

• of which sugars: ~ 0.3 g

• Starch: predominant component of total carbohydrates

• Dietary fibre: ~ 1.5–3 g (higher values in partially refined or “brown” Thaibonnet versions)

• Protein: ~ 7–8 g

• Total fat: ~ 1–3 g (depending on brand and degree of polishing)

• First occurrence SFA (Saturated Fatty Acids): present as a small fraction (tenths of a gram per 100 g); excessive SFA intake in the overall diet is associated with increased LDL cholesterol

• MUFA (MonoUnsaturated Fatty Acids): present in low absolute amounts, similar order of magnitude to SFA

• PUFA (PolyUnsaturated Fatty Acids): also low in absolute terms; the whole lipid fraction is small relative to carbohydrates

• Sodium: negligible in the raw grain (no added salt)

Values refer to uncooked parboiled Thaibonnet as typically sold for human consumption; they may vary slightly by producer, crop year, parboiling conditions and refinement degree (white vs. wholegrain).

Key constituents

• Complex carbohydrates (starch), with relatively high amylose content, associated with firm, non-sticky cooked grains

• Rice proteins (albumins, globulins, prolamins, glutelins) in moderate amount

• Lipid fraction: overall low; includes SFA, MUFA and PUFA in proportions typical of rice, but in small absolute quantities

• Dietary fibre: limited in milled white Thaibonnet, higher in wholegrain (brown) versions

• Vitamins and minerals: small amounts of B-group vitamins and minerals (e.g. phosphorus, magnesium); in parboiled products, part of the micronutrients from bran is driven towards the inner grain

• Rice phytocomponents (phenolic compounds, phytosterols, γ-oryzanol) mainly in bran layers; reduced in standard white Thaibonnet, more relevant in wholegrain variants

Production process

1. Cultivation and harvest

   • sowing of Oryza sativa L. cv. Thaibonnet in flooded or irrigated fields

   • growing cycle typical of Long B indica types, with late maturity and high yield potential

   • harvesting at full grain maturity by combine harvester

2. Drying of paddy rice

   • controlled drying to a safe moisture content for storage and processing

   • storage of paddy in silos pending further processing

3. Parboiling (for parboiled Thaibonnet)

   • soaking of paddy rice in water under controlled time and temperature

   • steaming / hydrothermal treatment to gelatinise starch and move certain micronutrients into the endosperm

   • re-drying to stable moisture content

4. Dehusking and milling

   • removal of the hull (dehusking)

   • optional whitening and polishing to obtain white crystalline Long B rice

   • removal of broken grains, foreign matter and off-spec kernels

5. Selection and packaging

   • optical and mechanical sorting of grains for uniformity and quality

   • packaging in bags, vacuum packs or protective atmosphere

   • labelling with variety/type (e.g. “Thaibonnet parboiled – Long B”) and mandatory nutritional information

Physical properties

• Commercial category: Long B rice (indica type)

• Grain morphology: long, very slender, needle-shaped; high length-to-width ratio

• Endosperm type: vitreous (crystalline), non-chalky

• Colour: bright white in refined form; light brown in wholegrain versions

• Raw texture: hard grain with good mechanical resistance during handling and industrial processing

• Cooking behaviour: high volume expansion with limited grain breakage when cooked under appropriate conditions

Sensory and technological properties

• Flavour: neutral to mildly cereal-like; wholegrain variants may show slightly more “nutty” or “bran-like” notes

• Aroma: generally delicate, not classed as aromatic rice (unlike basmati or jasmine)

• Texture after cooking:

  • well-separated grains, low stickiness

  • firm structure, with good resistance to overcooking

  • especially in parboiled form, suitable for holding time and reheating

• Technological behaviour:

  • ideal where a stable, non-creamy structure is needed (cold salads, side dishes, pilaf, buffet dishes)

  • good resistance to mixing, dressing and light sautéing

  • parboiled Thaibonnet shows reduced tendency to overcook and become mushy compared with some non-parboiled long-grain rices

Food applications

• Rice salads and cold cereal-based dishes

• Side dishes for meat, fish, legumes and vegetables where individual grains are desired

• Pilaf rice and other separate-grain dishes

• Dishes inspired by Indian and Asian cuisines, where a long, non-sticky grain is appropriate (curry accompaniments, spiced rice)

• Catering and food service, thanks to its cooking stability, ease of portioning and good performance under chilling and reheating

• Mixed dishes (rice–legume–vegetable) where structure retention is important, especially in combinations with sauces or dressings

Thaibonnet is less suitable for traditional creamy risottos, where japonica varieties (e.g. Carnaroli, Arborio, Vialone Nano) are preferred due to their starch behaviour.

Nutrition and health

Thaibonnet rice is a starchy cereal with:

• predominance of complex carbohydrates (starch)

• moderate protein content

• very low fat and sodium content

• absence of gluten (naturally gluten-free, provided there is no cross-contamination)

Parboiling can:

• help retain or redistribute certain B vitamins and minerals within the grain compared with non-parboiled white rice

• change starch structure (partial retrogradation), which may influence glycaemic response compared with some fully polished white rices, for a given portion

From a dietary perspective:

• portion size and condiments (oils, sauces, fats) are the main drivers of total energy and glycaemic load

• wholegrain Thaibonnet offers higher fibre and may be preferable in diets focusing on fibre intake

• the overall fatty acid profile of the diet depends more on added fats than on the rice, which has a very low intrinsic lipid content

Portion note

Indicative raw portions for Thaibonnet rice:

• main dish / substantial first course: ~ 70–80 g per person

• side dish: ~ 50–60 g per person

• mixed “one-dish” meals with legumes and vegetables: rice portion can be reduced (e.g. 50–60 g) and balanced with protein and vegetable components

Actual portions should be adapted to individual energy requirements, type of meal and overall diet.

Allergens and intolerances

• rice is naturally gluten-free and generally well tolerated

• not considered a major primary allergen; rice allergy exists but is relatively rare

• potential cross-contamination with gluten can occur in facilities that also process wheat or other gluten-containing cereals; “gluten-free” claims require compliance with legal thresholds

• rice usually has a relatively low FODMAP content compared with some other cereals, and is often suitable for individuals with functional bowel sensitivity, although individual responses vary

Storage and shelf-life

• store dry Thaibonnet rice in a cool, dry place, protected from light

• keep packaging closed after opening to prevent moisture uptake and insect infestation

• typical commercial shelf-life for dry Thaibonnet (parboiled or white) is around 24–36 months, depending on packaging and storage conditions (always check the “best before” date)

• avoid strong odours nearby, as rice can absorb volatile compounds

Cooked rice should be:

• cooled rapidly if not consumed immediately

• stored under refrigeration and consumed within about 24 hours, following good hygienic practices

Safety and regulatory aspects

• Thaibonnet rice is a traditional rice cultivar (not a novel food)

• subject to general food-law requirements on safety, contaminants, pesticide residues, microbiological criteria and traceability

• parboiled Thaibonnet must comply with limits for contaminants (e.g. heavy metals, mycotoxins) and hygiene parameters

• products intended for coeliac consumers must comply with gluten limits and labelling rules for “gluten-free” products

• any nutrition or health claims (e.g. “source of fibre”, “low fat”) must comply with applicable regulations and be supported by analytical data and validated claim lists

Labelling

For Thaibonnet rice sold as food, the label should indicate:

• sales name: e.g. “Thaibonnet parboiled Long B rice” (or equivalent national wording)

• country of origin (e.g. “Origin: Italy”), where required

• name and address of the food business operator

• net quantity

• date of minimum durability or use-by date

• storage conditions (e.g. “store in a cool, dry place”)

• nutritional declaration per 100 g of product

• indications such as “parboiled”, “wholegrain”, “for salads/pilaf”, where relevant

• any “gluten-free” or other claims only if the corresponding criteria are fulfilled

Troubleshooting

In cooking

• grains too firm after cooking

  • possible insufficient cooking time or too low water-to-rice ratio

  • action: increase cooking time slightly or adjust water volume; optionally use a brief pre-soak if compatible with the recipe

• grains too soft or broken

  • overcooking or excessive agitation

  • action: reduce cooking time; prefer absorption or pilaf methods with controlled water volume

• excessive stickiness

  • excessive water or very vigorous stirring; in some recipes, insufficient rinsing of surface starch (if rinsing is appropriate)

  • action: respect recommended water ratios; rinse rice before cooking when the culinary method allows; avoid over-stirring

In storage (dry product)

• presence of storage insects (small beetles, moths, larvae)

  • indicates infestation during prolonged storage

  • action: discard affected batches, clean storage areas, avoid very long storage times

• off-odours or foreign smells

  • possible absorption of surrounding odours or product oxidation/contamination

  • action: avoid storage near strong-smelling substances; check best-before date and packaging integrity

Main INCI functions (cosmetics)

Thaibonnet itself is not distinguished at cosmetic INCI level; ingredients are labelled at species level (Oryza sativa). Rice derivatives used in cosmetics include, for example:

• Oryza Sativa (Rice) Starch – used as absorbent, mattifying and texturizing agent in powders and make-up

• Oryza Sativa (Rice) Bran Oil – used as emollient and skin conditioning agent

• Oryza Sativa (Rice) Extract – used as skin conditioning and sometimes antioxidant component

Typical INCI functions:

• skin conditioning (improving skin feel and status)

• emollient (softening and reducing skin dryness)

• absorbent / opacifying (reducing surface shine and oiliness in powders and emulsions)

The specific variety (e.g. Thaibonnet) is generally not specified on cosmetic labels.

Conclusion

Thaibonnet is a Long B, indica-type rice cultivar, now well established in Italian rice production. Its grains are long, slender and vitreous, with high amylose content, good cooking stability and low stickiness. In parboiled form, Thaibonnet is particularly suited to rice salads, side dishes, pilaf and food-service applications, where grain separation, resistance to overcooking and good behaviour under cooling and reheating are essential.

Nutritionally, Thaibonnet parboiled rice has a profile consistent with other parboiled rices: predominance of complex carbohydrates, moderate protein content, very low fat and sodium, and natural absence of gluten. It can be part of a balanced diet, especially when portion size and condiments are managed appropriately and, where possible, when wholegrain variants are considered to increase fibre intake.

Within the broad range of rice types, Thaibonnet is best viewed as a technical long-grain option for separate-grain dishes, complementary (rather than alternative) to risotto rices. It is particularly useful in domestic and professional contexts that require high cooking stability and reliable technological performance in composite and cold rice dishes.

Mini-glossary

Long B rice – commercial class of long, slender rices (indica-type) with high length-to-width ratio and firm, separate grains after cooking.

Amylose – essentially linear starch fraction; higher amylose content is associated with firmer, less sticky cooked grains.

Amylopectin – branched starch fraction; higher proportions give more sticky/creamy textures and often higher glycaemic index.

Parboiled – hydrothermal treatment of paddy rice (soaking, steaming, drying) before milling, which hardens the grain, improves cooking stability and redistributes some micronutrients into the endosperm.

SFA – Saturated Fatty Acids; dietary fats that in excess are generally associated with increased LDL cholesterol.

MUFA – MonoUnsaturated Fatty Acids; dietary fats that, when replacing part of SFA, are usually considered more favourable for blood lipid profile.

PUFA – PolyUnsaturated Fatty Acids; dietary fats (n-6 and n-3 families) often associated with more favourable lipid profiles when appropriately balanced within the diet.

Studies

In general, rice contains more than 100 bioactive substances mainly in its bran layer including phytic acid, isovitexin, gamma-oryzanol, phytosterols, octacosanol, squalene, gamma-aminobutyric acid, tocopherol and derived from tocotrienol (1), antioxidants.

It does not contain beta carotene (provitamin A) and has a very low iron and zinc content (2).

In rice bran there are bioactive phytochemicals that exert protective actions against cancer that involve the metabolism of the host and the intestinal microbiome. A diet based on rice bran has shown positive effects in reducing the risk of colon cancer (3).

Rice studies

Allergies: Be careful, rice contains a certain amount of lactose.

The most common types of rice used are :

• Arborio : large grains,  the most common in Italy
• Ribe : elongated grains.
• Thaibonnet : medium, elongated and fine grains
• Rome : large grains
• Basmati : thin and elongated grains. Grown in Pakistan and India
• Carnaroli : large grains
• Vialone nano : large, round grains
• Original or Balilla : small round grains
• Jasmine : fine grains of Asian origin
• Red : red, small and narrow grains
• Wild : Zizania palustris
• Baldo : large, shiny grains
• Ganges : from India
• Footboard : releases a lot of starch
• Venus : from China and the Po Valley
• Patna : from Thailand. Long and narrow grains
• Sant'Andrea : Thick and long grains. Releases a lot of starch

Rice viruses and pests: Pseudomonas aeruginosa, Rice yellow mottle virus, Magnaporthe oryzae , Rice Tungro Bacilliform Virus , Lissorhoptrus oryzophilus Kuschel, Oebalus pugnax, Xanthomonas oryzae