Sirio rice (Oryza sativa L., Italian variety, Long B indica-type)

Description

Sirio rice is an Italian cultivar of Oryza sativa L. belonging to the Long B commercial group and classified agronomically as an indica-type rice. It was developed to provide a high-yielding, early-maturing variety with long, slender grains well suited to modern Italian paddy systems and to the industrial and household demand for separate-grain, non-creamy rice.

The decorticated Sirio grain is very long and narrow (length around 7.2 mm, width around 2.1 mm, length/width ratio ≈ 3.4). It has a crystalline endosperm, with no central pearl and no white streaks, a white pericarp and flattened cross-section. These features make it visually and technologically similar to many Asian long-grain rices and clearly different from pearled risotto rices such as Carnaroli or Arborio.

From an agronomic standpoint, Sirio (in the Sirio CL Clearfield® version) is characterised by very low plant height, early cycle, good vigour, high adaptability to direct seeding and a good tolerance to lodging. It is designed for integrated weed-control systems and is considered a reference grain within the Long B / indica market segment.

Culinarily, Sirio is used primarily as a long-grain, separate-kernel rice for salads, side dishes, pilaf and international-style preparations, where a dry, light texture and clear grain separation are required rather than creamy starch release.

Botanical classification
Common name: Sirio rice (Long B)
Clade: Angiosperms
Order: Poales
Family: Poaceae
Genus: Oryza
Species: Oryza sativa L.

Cultivation and growth conditions

Climate
Sirio rice is an Italian cultivar belonging to the Long B group, bred for the warm–temperate rice–growing areas of Italy. It requires hot summers and adequate water availability throughout the crop cycle. The variety is sensitive to low temperatures during germination, tillering and flowering, conditions that can reduce fertilization and yield.

Exposure
Like other paddy rice types, Sirio requires full sun to ensure high photosynthetic activity and proper panicle formation. Under shaded conditions, growth slows, yield decreases and plants are more exposed to competition from weeds.

Soil
The crop is generally grown on flat soils suitable for flooding, preferably clay or clay–loam soils with good water-holding capacity. Adequate organic matter and medium–high fertility are important. Very sandy, highly permeable soils are not suitable, as they do not allow a stable water layer to be maintained. Optimal pH ranges from slightly acidic to neutral or mildly alkaline.

Irrigation
Sirio rice is usually managed under flooded conditions, maintaining a water layer over the soil for much of the vegetative cycle. Careful regulation of water levels in the different stages (pre-emergence, tillering, stem elongation, ripening) is essential to control weeds, protect the crop from water stress and ensure uniform development. Uncontrolled water-level fluctuations or dry periods can compromise yield and grain quality.

Temperature
Optimal temperatures for germination are above 12–13 °C, while for vegetative growth and flowering ideal values are between about 20 and 30 °C. Cold episodes during anthesis reduce fertilization and grain set; conversely, intense heat combined with strong radiation and dry winds can cause grain scorching and quality defects.

Fertilization
Sirio rice requires balanced fertilization with nitrogen (N), phosphorus (P) and potassium (K):

• Nitrogen, split between pre-flooding and topdressings, promotes balanced tillering without increasing the risk of lodging;

• Phosphorus supports early root system development;

• Potassium improves lodging resistance and contributes to grain quality.

Excess nitrogen can increase the incidence of fungal diseases (e.g. blast), favour lodging and reduce yield stability.

Crop care
Main agronomic practices include:

• weed control through crop rotation, possible false sowing, mechanical methods and/or selective chemical treatments;

• accurate land levelling to ensure uniform flooding;

• careful management of water levels to limit unwanted aquatic species and reduce crop stress;

• monitoring of diseases (such as blast) and pests, adopting integrated pest management approaches;

• adjustment of sowing density to limit internal competition and reduce lodging risk.

Good air circulation within the crop canopy helps to limit diseases and maintain panicle quality.

Harvesting
Harvest takes place when grain ripening is uniform and grain moisture is suitable for combine harvesting. Excessive delay can cause lodging, shattering and loss of quality. After harvest, grain is dried to a moisture content appropriate for safe storage and subsequent processing.

Propagation
The Sirio cultivar is propagated using certified seed, produced in varietal seed multiplication plots to ensure genetic purity, grain uniformity and stable technological and cooking characteristics. On farm, paddy sowing (broadcast or in rows, on dry soil or under water) is carried out by adjusting the seed rate to the target plant density, soil fertility and the agronomic technique adopted.

Indicative nutritional values per 100 g
(white, milled Sirio rice, raw – estimated, in line with typical Long B white rices)

• Energy: ~ 340–360 kcal

• Water: ~ 8–13 g

• Total carbohydrates: ~ 75–78 g

  • predominantly starch (amylose + amylopectin)

• Dietary fibre: ~ 0.5–2 g (low in the fully milled product)

• Protein: ~ 7–8 g

• Total fat: ~ 0.4–1.0 g

  • first occurrence SFA (Saturated Fatty Acids): small fraction of the total fat; in the overall diet, excessive SFA intake is associated with increased LDL cholesterol

  • MUFA (MonoUnsaturated Fatty Acids): minor fraction

  • PUFA (PolyUnsaturated Fatty Acids): minor fraction, often similar to or slightly higher than MUFA

Micronutrients (B-group vitamins, minerals such as phosphorus, magnesium, iron, zinc) are present in modest amounts typical of white milled rice; they are more abundant in wholegrain or semi-milled forms.

Key constituents

• Complex carbohydrates

  • starch (amylose + amylopectin) as the main energy source

  • relatively high amylose level for a long-grain rice, favouring dry cooked texture

• Proteins

  • rice storage proteins in moderate quantity

• Lipid fraction

  • very low total fat, with SFA, MUFA and PUFA present in small absolute amounts

• Dietary fibre

  • low in refined white Sirio, higher in semi-whole or wholegrain processing

• Micronutrients and minor components

  • B-group vitamins and minerals in small amounts

  • phenolic compounds and phytosterols mainly associated with outer layers removed during polishing

Production process

1. Cultivation

   • sowing of Sirio (often Sirio CL Clearfield®) in Italian paddy fields

   • crop management under flooded or semi-flooded conditions, with attention to direct seeding, weed control, fertilisation and disease management

   • early vegetative cycle with good tillering capacity and low plant height, which supports high yield and reduced lodging risk

2. Harvesting

   • mechanical harvest of paddy (rough rice) at full grain maturity

3. Drying

   • controlled drying of paddy to safe moisture levels for storage

4. Cleaning and storage

   • mechanical cleaning to remove straw, soil, stones and other foreign materials

   • storage in silos with monitoring of temperature and humidity

5. Dehusking and milling

   • dehusking to obtain brown Sirio rice

   • for white Sirio: whitening/polishing to remove bran and germ and to obtain the crystalline Long B grain

6. Sorting and packaging

   • optical and mechanical sorting to eliminate broken and defective kernels

   • packaging in bulk or consumer packs, usually indicated as “Sirio” or generically as Long B rice

Physical properties

• Grain type: Long B, very long and slender

• Grain length (decorticated): ≈ 7.2 mm

• Grain width: ≈ 2.1 mm

• Length/width ratio: ≈ 3.4 (very long)

• Shape: very long, flattened cross-section, oblong head, elusive “tooth” at the apex

• Pericarp colour: white

• Endosperm: crystalline, non-pearled, non-aromatic

Sensory and technological properties

• Flavour: neutral, mild cereal taste, designed to carry sauces and accompaniments rather than to dominate

• Aroma: non-aromatic; no specific perfumed notes as in jasmine or basmati

Cooking behaviour

• good resistance to disintegration with proper cooking conditions

• low surface stickiness if water ratio and time are correctly managed

• cooked grains remain separate, light and dry, with very limited clumping

• suitable for boiling and draining, absorption methods and pilaf

Technological aspects

• suitable for cold preparations (salads, buffet dishes) thanks to good grain stability after cooling

• performs well in industrial and catering settings where holding and reheating may occur

• not suited to creamy applications where strong starch release and sauce-binding from the rice itself are desired (e.g. classic risotto)

Food uses

• rice salads and cold mixed dishes

• side dishes served with meat, fish, pulses or vegetable mains

• pilaf-type dishes and international recipes calling for long, separate grains

• components of ready meals where grain identity and low stickiness are important

• base for cereal-based one-dish meals (rice with vegetables, pulses and lean proteins)

It is generally not used for:

• traditional Italian risotto

• dishes requiring high creaminess and strong starch release by the rice

Nutrition and health

Sirio behaves nutritionally like other refined long-grain white rices:

• it is a source of complex carbohydrates, providing readily usable energy

• it contains moderate protein and very little fat, with a small portion of saturated fat

• refined Sirio has low fibre compared with wholegrain rice

• it is naturally gluten-free, so it can be used in coeliac diets and gluten-free patterns if cross-contamination is controlled

The glycaemic impact of Sirio is influenced by:

• portion size (larger portions increase glycaemic load)

• degree of refining (white vs semi-whole/whole)

• overall meal composition (presence of fibre, proteins and fats that modulate digestion and absorption)

Within a balanced diet, Sirio can be included as the carbohydrate component of meals, ideally combined with vegetables, pulses and quality fats to improve the nutritional profile of the dish.

Portion note

Indicative dry Sirio rice portions:

• as main carbohydrate component of a meal: 70–80 g per person

• as a side dish: 50–60 g per person

These values should be adapted to individual energy requirements, physical activity and overall meal structure.

Allergens and intolerances

• Sirio rice is naturally gluten-free and suitable for people with coeliac disease or gluten intolerance, provided that production and packing avoid cross-contact with gluten-containing cereals

• true rice allergy is uncommon but possible in sensitised individuals

• digestion is generally good; any discomfort is typically related to overall meal composition rather than to the variety itself

Storage and shelf-life

Raw Sirio rice

• store in a cool, dry place, away from direct sunlight and strong odours

• keep in original sealed packaging, or transfer to airtight containers after opening

• under appropriate storage conditions, white Sirio rice typically has a shelf-life of up to about 24 months, according to producer indications

Cooked Sirio rice

• cool rapidly if not consumed immediately

• store refrigerated in closed containers

• consume preferably within 24 hours, following good hygiene practices

Safety and regulatory aspects

• Sirio rice is regulated under general legislation for rice and cereal products

• subject to legal limits on contaminants (pesticide residues, heavy metals, mycotoxins) and to microbiological criteria

• must comply with requirements on food safety management, hygiene, traceability and correct labelling

• when used in schemes that classify by grain type (e.g. Long B indica), it must satisfy the relevant morphological and quality specifications

Labelling

On consumer packs, Sirio rice is typically labelled with:

• product name: e.g. “Sirio rice” or “Long B rice – Sirio variety”

• rice type: Long B / indica-type

• net quantity

• best-before date and batch identification

• storage instructions (“store in a cool, dry place”)

• nutrition declaration per 100 g (and sometimes per serving)

• country of origin/production where required

• cooking instructions (water/rice ratio, time)

• any voluntary claims (e.g. “gluten-free”, “wholegrain”, “organic”) only when all regulatory conditions are met

Troubleshooting

In cooking

• Grains too sticky or clumped

  • possible causes: too much water, overcooking, insufficient rinsing before cooking

  • corrective measures:

    • rinse the rice until the rinse water is less cloudy

    • reduce the water/rice ratio

    • respect recommended cooking times and avoid vigorous stirring

• Grains too firm or undercooked

  • possible causes: insufficient water or cooking time

  • corrective measures:

    • extend cooking slightly with a small addition of hot water

    • adjust the water ratio and time for future preparations

In storage

• Insect infestation

  • source: long storage in warm, humid conditions or non-airtight containers

  • solution: discard infested product, clean storage area, use sealed containers and cool, dry storage

• Off-odours or stale notes

  • source: storage near strongly scented foods or products, or excessively long storage time

  • solution: store away from strong odours; respect best-before dates and recommended conditions

Main INCI functions (cosmetics)

Cosmetic ingredients do not differentiate rice varieties such as Sirio. At INCI level, rice-based cosmetic ingredients are listed under Oryza sativa. Common examples include:

• Oryza Sativa (Rice) Starch – used as absorbent, opacifying and texturising agent

• Oryza Sativa (Rice) Bran Oil – skin conditioning and emollient oil for skin and hair products

• Oryza Sativa (Rice) Extract – used mainly for skin conditioning and providing minor antioxidant and protective components

Sirio can be one of the agricultural sources for these ingredients, but the specific variety is not indicated on the label.

Conclusion

Sirio rice is a modern Italian Long B indica-type variety, developed to combine early maturity, low plant height and high yield with a very long, slender crystalline grain. Its technological profile makes it particularly well suited to separate-grain dishes such as rice salads, pilaf and side dishes, both in domestic and professional kitchens.

Nutritionally, Sirio is comparable to other refined long-grain white rices: it is rich in complex carbohydrates, contains moderate protein, very little fat and is naturally gluten-free. Its role in a healthy diet depends largely on portion control and on how it is combined with vegetables, pulses, fats and other ingredients.

Whenever a light, dry, separate-kernel rice is required rather than a creamy, starch-rich rice, Sirio represents a coherent and functional choice.

Mini-glossary

• Long B rice – commercial class of rice with very long, slender grains and high length/width ratio, typically used for separate-grain dishes.

• Crystalline endosperm – translucent, glassy grain interior with no central white pearl, typical of many indica-type long-grain rices.

• Indica-type rice – botanical/agronomic grouping of Oryza sativa characterised by long, slender grains and tropical–subtropical adaptation, distinct from japonica types.

• Amylose – linear starch fraction; higher levels generally result in drier, less sticky cooked rice.

• Gluten-free – absence of gluten (storage proteins typical of wheat, barley and rye); all rice, including Sirio, is naturally gluten-free.

• SFA – Saturated Fatty Acids; dietary fats that, in excess, are linked with increased LDL cholesterol.

• MUFA – MonoUnsaturated Fatty Acids; unsaturated fats that may improve lipid profiles when they replace some SFA.

• PUFA – PolyUnsaturated Fatty Acids; include n-6 and n-3 fatty acids, involved in many physiological processes when consumed in appropriate amounts and balance.

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

References____________________________________________________________________

(1)  Bidlack W. Phytochemicals as bioacive agents. Lancaster, Basel, Switzerland: Technomic Publishing Co., Inc; 1999. pp. 25–36.

(2) Singh SP, Gruissem W, Bhullar NK.   Single genetic locus improvement of iron, zinc and β-carotene content in rice grains.    Sci Rep. 2017 Jul 31;7(1):6883. doi: 10.1038/s41598-017-07198-5.

Abstract. Nearly half of the world's population obtains its daily calories from rice grains, which lack or have insufficient levels of essential micronutrients. The deficiency of micronutrients vital for normal growth is a global health problem, and iron, zinc and vitamin A deficiencies are the most prevalent ones. We developed rice lines expressing Arabidopsis NICOTIANAMINE SYNTHASE 1 (AtNAS1), bean FERRITIN (PvFERRITIN), bacterial CAROTENE DESATURASE (CRTI) and maize PHYTOENE SYNTHASE (ZmPSY) in a single genetic locus in order to increase iron, zinc and β-carotene content in the rice endosperm. NAS catalyzes the synthesis of nicotianamine (NA), which is a precursor of deoxymugeneic acid (DMA) iron and zinc chelators, and also chelate iron and zinc for long distance transport. FERRITIN provides efficient storage of up to 4500 iron ions. PSY catalyzes the conversion of GGDP to phytoene, and CRTI performs the function of desaturases required for the synthesis of β-carotene from phytoene. All transgenic rice lines have significantly increased β-carotene, iron, and zinc content in the polished rice grains. Our results establish a proof-of-concept for multi-nutrient enrichment of rice grains from a single genetic locus, thus offering a sustainable and effective approach to address different micronutrient deficiencies at once.

(3) Zarei I, Oppel RC, Borresen EC, Brown RJ, Ryan EP. Modulation of plasma and urine metabolome in colorectal cancer survivors consuming rice bran.  Integr Food Nutr Metab. 2019 May;6(3). doi: 10.15761/IFNM.1000252.

Abstract. Rice bran has bioactive phytochemicals with cancer protective actions that involve metabolism by the host and the gut microbiome. Globally, colorectal cancer (CRC) is the third leading cause of cancer-related death and the increased incidence is largely attributed to poor dietary patterns, including low daily fiber intake. A dietary intervention trial was performed to investigate the impact of rice bran consumption on the plasma and urine metabolome of CRC survivors. Nineteen CRC survivors participated in a randomized-controlled trial that included consumption of heat-stabilized rice bran (30 g/day) or a control diet without rice bran for 4 weeks. A fasting plasma and first void of the morning urine sample were analyzed by non-targeted metabolomics using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After 4 weeks of either rice bran or control diets, 12 plasma and 16 urine metabolites were significantly different between the groups (p≤0.05). Rice bran intake increased relative abundance of plasma mannose (1.373-fold) and beta-citrylglutamate (BCG) (1.593-fold), as well as increased urine N-formylphenylalanine (2.191-fold) and dehydroisoandrosterone sulfate (DHEA-S) (4.488-fold). Diet affected metabolites, such as benzoate, mannose, eicosapentaenoate (20:5n3) (EPA), and N-formylphenylalanine have been previously reported for cancer protection and were identified from the rice bran food metabolome. Nutritional metabolome changes following increased consumption of whole grains such as rice bran warrants continued investigation for colon cancer control and prevention attributes as dietary biomarkers for positive effects are needed to reduce high risk for colorectal cancer recurrence.

Brown DG, Borresen EC, Brown RJ, Ryan EP. Heat-stabilised rice bran consumption by colorectal cancer survivors modulates stool metabolite profiles and metabolic networks: a randomised controlled trial. Br J Nutr. 2017 May;117(9):1244-1256. doi: 10.1017/S0007114517001106. 

Abstract. Rice bran (RB) consumption has been shown to reduce colorectal cancer (CRC) growth in mice and modify the human stool microbiome. Changes in host and microbial metabolism induced by RB consumption was hypothesised to modulate the stool metabolite profile in favour of promoting gut health and inhibiting CRC growth. The objective was to integrate gut microbial metabolite profiles and identify metabolic pathway networks for CRC chemoprevention using non-targeted metabolomics. In all, nineteen CRC survivors participated in a parallel randomised controlled dietary intervention trial that included daily consumption of study-provided foods with heat-stabilised RB (30 g/d) or no additional ingredient (control). Stool samples were collected at baseline and 4 weeks and analysed using GC-MS and ultra-performance liquid chromatography-MS. Stool metabolomics revealed 93 significantly different metabolites in individuals consuming RB. A 264-fold increase in β-hydroxyisovaleroylcarnitine and 18-fold increase in β-hydroxyisovalerate exemplified changes in leucine, isoleucine and valine metabolism in the RB group. A total of thirty-nine stool metabolites were significantly different between RB and control groups, including increased hesperidin (28-fold) and narirutin (14-fold). Metabolic pathways impacted in the RB group over time included advanced glycation end products, steroids and bile acids. Fatty acid, leucine/valine and vitamin B6 metabolic pathways were increased in RB compared with control. There were 453 metabolites identified in the RB food metabolome, thirty-nine of which were identified in stool from RB consumers. RB consumption favourably modulated the stool metabolome of CRC survivors and these findings suggest the need for continued dietary CRC chemoprevention efforts.

Beyer P, Al-Babili S, Ye X, Lucca P, Schaub P, Welsch R, Potrykus I. Golden Rice: introducing the beta-carotene biosynthesis pathway into rice endosperm by genetic engineering to defeat vitamin A deficiency. J Nutr. 2002 Mar;132(3):506S-510S. doi: 10.1093/jn/132.3.506S. 

 Abstract. To obtain a functioning provitamin A (beta-carotene) biosynthetic pathway in rice endosperm, we introduced in a single, combined transformation effort the cDNA coding for phytoene synthase (psy) and lycopene beta-cyclase (beta-lcy) both from Narcissus pseudonarcissus and both under the control of the endosperm-specific glutelin promoter together with a bacterial phytoene desaturase (crtI, from Erwinia uredovora under constitutive 35S promoter control). This combination covers the requirements for beta-carotene synthesis and, as hoped, yellow beta-carotene-bearing rice endosperm was obtained in the T(0)-generation. Additional experiments revealed that the presence of beta-lcy was not necessary, because psy and crtI alone were able to drive beta-carotene synthesis as well as the formation of further downstream xanthophylls. Plausible explanations for this finding are that these downstream enzymes are constitutively expressed in rice endosperm or are induced by the transformation, e.g., by enzymatically formed products. Results using N. pseudonarcissus as a model system led to the development of a hypothesis, our present working model, that trans-lycopene or a trans-lycopene derivative acts as an inductor in a kind of feedback mechanism stimulating endogenous carotenogenic genes. Various institutional arrangements for disseminating Golden Rice to research institutes in developing countries also are discussed.