Carnaroli rice (Oryza sativa L., japonica group, Long A)

Description

Carnaroli rice is an Italian variety of Oryza sativa L. belonging to the japonica group and to the commercial class Long A. It is considered one of the reference rices for risotto, due to the combination of grain structure, high cooking stability and ability to absorb liquids and flavours while maintaining a firm core.

The grain is long, fairly large and semi-round, with a characteristic central pearl (slightly opaque zone in the endosperm). This internal structure, combined with a relatively high amylose content (higher than many other common risotto rices), makes Carnaroli less sticky and highly resistant to overcooking. During cooking it can release enough surface starch to form a creamy sauce, while the internal part of the grain remains compact and “al dente”.

Carnaroli is traditionally cultivated in the rice plains of Northern Italy (especially Lombardy and Piedmont). From an agronomic point of view, it is a medium–late cycle japonica with relatively tall plants, and requires careful management of sowing density, water level and nitrogen fertilisation to obtain uniform, defect-free grains suitable for premium culinary uses.

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

Cultivation and growth conditions

Climate
Carnaroli rice is a paddy cultivar typical of warm–temperate regions, with hot summers and abundant water availability throughout the growing season. It needs a frost-free vegetative period, with high temperatures during tillering, stem elongation and ripening. It is particularly sensitive to low temperatures during germination and flowering, which can impair fertilization and reduce yield.

Exposure
Like most paddy varieties, Carnaroli requires full sun to ensure high photosynthetic activity and good panicle formation. Prolonged shading or competition from tall vegetation along field borders reduces plant development and favours the spread of weeds.

Soil
Carnaroli is generally grown on flat soils suitable for flooding. Optimal soils are clay or clay–loam, with good water-holding capacity and adequate organic matter. Very sandy, highly permeable soils are not suitable, as they prevent the maintenance of a uniform water layer. The ideal pH is from slightly acidic to neutral or mildly alkaline.

Irrigation
Carnaroli rice is usually managed under continuous flooding for a large portion of the crop cycle. Water levels must be carefully regulated in the different stages (pre-emergence, tillering, stem elongation, ripening) to limit weed pressure, ensure uniform growth and reduce water stress. Sudden drops in water level or unplanned dry phases can compromise yield and technological quality.

Temperature
Optimal temperatures for germination are above 12–13 °C, while for vegetative growth and flowering the ideal range is about 20–30 °C. Cold episodes during anthesis reduce fertilization; conversely, prolonged heat stress combined with intense radiation and dry winds can cause grain scorching and quality defects (chalkiness, breakage).

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

• Nitrogen should be applied in split doses (before flooding and as topdressings) to ensure regular tillering without excessive lodging.

• Phosphorus supports early root system development.

• Potassium improves lodging resistance and several aspects of grain quality.

Excess nitrogen favours fungal diseases (such as blast), increases lodging risk and makes the crop more susceptible to insect attacks.

Crop care
Main management practices include:

• weed control through crop rotation, possible false sowing, and targeted mechanical and/or chemical interventions;

• accurate land levelling to ensure uniform flooding;

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

• monitoring of diseases (e.g. blast) and pests, applying integrated pest management strategies where possible;

• selection of an appropriate sowing density to limit internal competition and lodging risk.

Good air circulation within the crop canopy helps limit diseases and supports final product quality.

Harvesting
Harvest takes place when grain ripening is uniform and grain moisture is suitable for combine harvesting. Excessive delay increases the risk of lodging, grain loss and quality deterioration. After harvest, grain is dried to a moisture content suitable for safe storage and subsequent processing (dehusking, polishing, packing).

Propagation
The Carnaroli cultivar is propagated using certified seed, produced in selected seed multiplication plots to guarantee uniform grain type, cooking behaviour and technological characteristics. On farm, paddy sowing (broadcast or in rows, on dry soil or in water) is carried out by adjusting the seed rate according to target plant density and the agronomic technique adopted.

Indicative nutritional values per 100 g

(raw white Carnaroli rice – average values)

• Energy: about 350–360 kcal

• Water: ~ 8–12 g

• Total carbohydrates: ~ 77–80 g

  • mainly starch

• Dietary fibre: ~ 0.8–1.5 g

• Protein: ~ 7–8 g

• Total fat: ~ 0.4–0.7 g

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

  • MUFA (MonoUnsaturated Fatty Acids): present in small amounts and generally considered preferable to SFA when replacing part of them

  • PUFA (PolyUnsaturated Fatty Acids): present in small amounts, contributing to the unsaturated lipid fraction

Sodium is naturally negligible in the raw grain. Values can vary slightly according to brand, origin and analytical method.

Key constituents

• Complex carbohydrates

  • starch composed of amylose and amylopectin, with a comparatively high amylose fraction for a risotto rice

• Proteins

  • rice storage proteins (albumins, globulins, prolamins, glutelins) in moderate amounts

• Lipid fraction

  • very low total fat, made up of saturated, monounsaturated and polyunsaturated fatty acids in small absolute quantities

• Dietary fibre

  • small amount in white Carnaroli; more in wholegrain forms if produced

• Micronutrients

  • small amounts of B-group vitamins

  • minerals such as phosphorus, magnesium, zinc and manganese in trace–moderate levels

• Minor and surface components

  • phenolic compounds and other phyto-components mainly located in the bran layers, largely reduced in the polished product

Production process

1. Cultivation and harvest

   • cultivation in Italian paddy fields under flooded conditions

   • management of fertilisation, water level and phytosanitary protection

   • harvest at full grain maturity with combine harvesters

2. Drying

   • controlled drying of paddy rice to safe moisture levels for storage

3. Cleaning and storage

   • removal of foreign materials (soil, straw, stones, weed seeds)

   • storage in silos with control of moisture, temperature and storage pests

4. Dehusking and milling

   • dehusking to obtain brown Carnaroli rice

   • whitening and, where required, light polishing to obtain white Carnaroli Long A

   • optical and mechanical sorting to remove broken or defective kernels

5. Packaging

   • packing in bags or vacuum/modified atmosphere packs

   • labelling with variety name, origin, best-before date, nutritional information and cooking instructions

Physical properties

• Grain type: Long A, medium-large and semi-round

• Colour (white Carnaroli): uniform white, sometimes slightly ivory

• Endosperm: compact with evident central pearl

• Raw grain: hard and mechanically resistant, suitable for stirring during cooking

• Water absorption: high, with significant increase in volume during cooking

Sensory and technological properties

• Flavour: neutral to mildly cereal-like, designed to carry and support sauces and flavourings rather than dominate them

• Aroma: non-aromatic rice (no specific perfumed notes such as in basmati or jasmine rice)

Cooking behaviour

• high resistance to overcooking

• good ability to absorb stock and condiments

• controlled release of surface starch, allowing formation of a creamy matrix without the grain collapsing

• suitable for repeated stirring and gradual liquid addition typical of risotto technique

Technological aspects

• well adapted to sautéing/toasting and deglazing at the start of risotto preparation

• shows good stability during service, with slower decay of texture compared with many other risotto rices

• particularly suitable when precise control over grain firmness and final creaminess is required

Food applications

• Traditional and modern risottos (meat, fish, vegetables, cheese, aromatic reductions)

• Structured dishes such as timbales, baked rice moulds and fillings where a creamy but coherent structure is needed

• High-end restaurant preparations where cooking tolerance and consistency between portions are critical

Less typical uses:

• cold rice salads requiring very separate grains over long holding times

• preparations where extreme grain dryness and separation are preferred over creaminess

Nutrition and health

From a nutritional perspective, Carnaroli behaves like other polished white japonica rices:

• provides mainly complex carbohydrates as energy source

• has a moderate protein content and very low total fat, with limited saturated fat

• has relatively low fibre in polished form

• is naturally gluten-free, making it suitable for coeliac diets if cross-contamination is avoided

Health impact depends largely on:

• portion size and frequency of consumption

• composition of the dish (quantity and type of fats, presence of vegetables and pulses, added salt)

• overall dietary pattern (balance of wholegrains vs refined grains, total energy intake, etc.)

Carnaroli can form part of a balanced diet when risotti are prepared with moderate amounts of fats and accompanied by vegetables and suitable protein sources.

Portion note

Indicative dry Carnaroli quantities:

• main course risotto: approx. 70–80 g per person

• smaller portion or side: approx. 50–60 g per person

These values should be adjusted according to individual energy needs, menu structure and presence of other courses.

Allergens and intolerances

• Carnaroli rice is gluten-free by nature; it can be consumed by people with coeliac disease or gluten intolerance if produced and handled without cross-contact with gluten-containing cereals

• rice allergy is uncommon but possible in sensitised individuals

• digestion is usually good; any discomfort is more often related to the overall meal composition (fats, sauces) than to the rice itself

Storage and shelf-life

Raw Carnaroli

• store in a cool, dry place, protected from light and strong odours

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

• typical shelf-life for properly stored white Carnaroli: up to about 24 months, depending on producer indications and storage conditions

Cooked Carnaroli

• if not served immediately, cool rapidly

• store in the refrigerator in closed containers

• consume preferably within 24 hours, respecting good hygiene practices

Safety and regulatory

• Carnaroli is a traditional cereal and falls under general regulations for rice and cereal products

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

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

• when labelled as “gluten-free”, must respect regulatory thresholds for gluten content and be produced under controlled conditions

Labelling

For packaged Carnaroli rice, the label normally includes:

• product name (e.g. “Carnaroli rice – Long A risotto rice”)

• variety: “Carnaroli”

• 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 time and basic preparation instructions

• any voluntary claims (e.g. “gluten-free”) only when conditions for such claims are fulfilled

Troubleshooting

In cooking

• Grains too soft or broken

  • possible causes: excessive cooking time, overly vigorous boiling or stirring

  • corrective measures: reduce cooking time, maintain gentle simmer, stir firmly but not aggressively

• Centre of grains too hard

  • possible cause: insufficient cooking or liquid addition

  • corrective measures: extend cooking by a few minutes, add small amounts of hot stock gradually while stirring

• Risotto too dry or compact

  • possible causes: insufficient stock or evaporation too rapid

  • corrective measures: add more hot stock in small additions, adjust heat, finish with appropriate fat (butter, oil) during mantecatura

In storage

• Off-odours or staleness in raw rice

  • possible causes: storage near strong odours or in warm, humid conditions

  • corrective measures: use airtight containers, store away from aromatic products, respect best-before dates

Main INCI functions (cosmetics)

Carnaroli is not distinguished at INCI level; cosmetic ingredients refer to rice in general as Oryza sativa. Common rice-derived INCI ingredients include:

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

• Oryza Sativa (Rice) Bran Oil – emollient and skin conditioning lipid fraction from rice bran

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

Carnaroli may be one of the possible rice sources, but the variety is not indicated on the INCI list.

Conclusion

Carnaroli rice is a key Italian japonica Long A variety specifically appreciated for risotto preparation. Its long, semi-round grain, central pearl and relatively high amylose content give a combination of strong cooking resistance, good liquid absorption and controlled starch release, allowing the preparation of risotti that are both creamy and with well-defined, al dente grains.

Nutritionally, Carnaroli is comparable to other white rices: mainly complex carbohydrates, moderate protein, very low fat and naturally gluten-free. Its role in health is determined less by the variety itself and more by how it is used in recipes (portion sizes, type and amount of fats used, presence of vegetables and other ingredients).

In both professional and home kitchens, Carnaroli is widely regarded as a premium option when precise control over texture and creaminess is required, and remains one of the most important varieties in the Italian risotto tradition.

Mini-glossary

• Amylose – linear starch fraction; higher levels generally increase grain firmness and reduce stickiness after cooking.

• Amylopectin – branched starch fraction; contributes to surface starch release and creaminess in cooking.

• Long A – commercial class of rice with long but relatively broad grains, typical of many japonica risotto rices.

• Central pearl – opaque central area of the grain endosperm associated with particular textural and cooking properties.

• SFA – Saturated Fatty Acids; fats that, when consumed in excess, are linked to increased LDL cholesterol.

• MUFA – MonoUnsaturated Fatty Acids; unsaturated fats generally considered favourable when they replace part of SFA in the diet.

• PUFA – PolyUnsaturated Fatty Acids; include n-6 and n-3 fatty acids, important for various physiological functions 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.