Browsing by Author "Lemos, Diogo"
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- Amylose content of rice marketed in PortugalPublication . Correia, Paula; Santos, Tania; Lemos, Diogo; Brites, Carla; Guiné, RaquelAmylose content is considered to be the most important parameter of cooking quality in rice. Presently, rice cultivars are categorized according to amylose content into three groups: low, medium and high amylose content cultivars. The specific objective of this work is to evaluate the grain amylose content of 77 cultivars, which cover Índica and Japónica subspecies, and different types of commercial rice like, aromatic (basmati and thay), wild rice, medium rice (carlose and risotto), glutinous (waxy) and parboiled rice. Generally, these types of rice are the ones commercialized in Portugal The encountered results showed that in the same group the amylose contents were consistent, and could present great variance, as it is the case of Indica subspecies, which vary between 12.0% to 29.5%, and presenting the high amylose percentages. Thus, these intermediate amylose rices could give moist and tender upon cooking. It is also important to mention that amylose consists of linearly linked glucose molecules and is relatively resistant to digestion, hence the term “resistant starch”. This means that these rice cultivars with a greater proportion of starch in the form of amylose tend to have a lower glycemic index, and could be recommended for special diets. The low values were presented for glutinous rice (1.9% and 3.3%), which means that these type of rice do not expand in volume, are glossy and sticky, and remain firm when cooked. Intermediate values were found for parboiled rice. The majority of rice types presented low amylose content, range from 9% to 19%.
- Contribuition for the physical characterization of carolino ricePublication . Correia, Paula; Alves, Mariana; Lemos, Diogo; Guiné, RaquelMost of the rice produced in Portugal is of the Carolino type, botanically classified as Oryza sativa ssp. Japonica. Nowadays, this rice is playing a vital role in Portuguese rice trading, and therefore the aim of this work was to evaluate some cultivars as to biometric characteristics, water uptake ratio, cooking time and textural properties. Five types of Carolino rice were collected for analysis. Biometric characteristics (length, width, length/width ratio) were evaluated using an automatic biometric equipment. Other morphological characteristics were evaluated: white vitreous, total whiteness, vitreous percentage, percentage of chalky area and kett (using a colorimeter). Texture was evaluated on compression by texture profile analysis with a texturometer. The samples studied showed biometric characteristics to be commercially classified as long grains type-A. The results indicated that one of the samples was quite different from the others, presenting less adhesiveness, and lower hardness, springiness and cohesiveness. Also some differences were found between different rice samples regarding colour characteristics, cooking time and water absorption.
- Contribution for physical characterization of aromatic ricePublication . Correia, Paula; Alves, Mariana; Lemos, Diogo; Guiné, RaquelIntroduction: Rice is consumed mainly as whole grain, and quality considerations are much more important than for any other food crop. Rice grain quality preference varies from country to country and among regions. Nowadays, aromatic rice varieties are playing a vital role in global rice trading, and also in Portugal. The economic value of rice depends on its cooking and processing quality, such us water uptake ratio, cooking time and texture properties. Materials and methods: Three types of aromatic rice were collected and analysed for biometry characteristics, cooking time, water absorption, and texture properties.The rice grains were collected from the Portuguese trade market. Biometric characteristics of all rice grains were evaluated by S21 (LKL) and C-300 (Kett) colorimeter. The rice flour texture was performed by a TPA (texture profile analysis), giving information about adhesiveness, chewiness, gumminess, hardness, resilience and cohesiveness. The extrusion force was also determined according to ISO 11747:2012. Results: Rice samples are commercially classified as long grains B type, because they presented a length higher than 6 mm and the ratio length/width higher than 3. The samples presented a high degree of whiteness, with a strictly relationship between the total and vitrea whiteness (r2=0.95). The cooking time varied from 12 to 17 minutes and this properties was strongly related with water uptake (from 155.7 – 209.1 g). Generally, aromatic rice cultivars presented different textural properties. Aromatic rice samples are different for hardness, adhesiveness, gumminess, resilience and extrusion force. Conclusions: From the results obtained it was concluded that the studiedc aromatic rice cultivars presented different physical properties, mainly the cooking time, water uptake and texture. These differences could be a commercial advantage considering the consumer point of view, because the enterprise could provide a specific aromatic rice in order to attend different consumer targets.
- Contribution for physical characterization of aromatic ricePublication . Correia, Paula; Alves, Mariana; Lemos, Diogo; Guiné, RaquelRice is consumed mainly as whole grain, and quali- ty considerations are much more important than for any other food crop. Rice grain quality preference varies from country to country and among regions. Nowadays, aromatic rice varieties are playing a vital role in global rice trading, and also in Portugal. The economic value of rice depends on its cooking and processing quality, such us water uptake ratio, cooking time and texture properties. Three types of aromatic rice were collected and ana- lyzed for biometry characteristics, cooking time, wa- ter absorption, and texture properties. The rice grains were collected from the Portuguese trade market. Biometric characteristics of all rice grains were eval- uated by S21 (LKL) and C-300 (Kett) colorimeter. The rice flour gels texture was performed by a TPA (texture profile analysis), giving information about adhesive- ness, chewiness, gumminess, hardness, resilience and cohesiveness. The extrusion force was also determined according to ISO 11747:2012. Rice samples are commercially classified as long grains B type, because they presented a length higher than 6 mm and the ratio length/ width higher than 3. The samples presented a high degree of whiteness, with a strictly relationship between the total and vitrea white- ness (r 2 = 0.95). The cooking time varied from 12 to 17 minutes and these properties was strongly related with water uptake (from 155.7 - 209.1 g). Generally, aromat- ic rice cultivars presented different textural properties. Aromatic rice samples are different for hardness, adhe- siveness, gumminess, resilience, and extrusion force. From the results obtained it was concluded that the studied aromatic rice cultivars presented different physical properties, mainly the cooking time, water uptake and texture. These differences could be a com- mercial advantage considering the consumer point of view, because the enterprise could provide specif- ic aromatic rice in order to attend different consumer targets.
- Contribution for physical characterization of carolino ricePublication . Correia, Paula; Alves, Mariana; Lemos, Diogo; Guiné, RaquelMost of the rice produced in Portugal is of the Carolino type, botanically classified as Oryza sativa ssp. Japonica. Nowadays, this rice is playing a vital role in Portuguese rice trading. Five types of Carolino rice were collected and analysed for biometry characteristics, cooking time, water absorption, and texture properties. The Carolino rices studued are commercially classified as long grains type-A, because they present a length higher than 6 mm and the ratio length/width lower than 3 mm. This type of rice showed a high level of plastered area, meaning low vitrea aspect, with a negative strong correlation (r2=-0.99), and it was observed a great discrepancy for the study cultivars. The cooking time varied from 17 to 22 minutes, with a water uptake between 143.9 and 182.5 g after achieving the cooking point. To compare the differences between the cultivars, the cooking time was also determined after 13 minutes of cooking, and the results showed that the water absorption veried from 101.9 to 139.6 g. Carolino rice flours were quite different considering the results of TPA (texture profile analysis). One of the samples was quite different from the others, presenting less adhesiveness, chewiness, gumminess, hardness, resilience and cohesiveness. The extrusion force (kg/cm2) was similar between the five cultivars. In general, it could be concluded that in spite of the samples belonging to the same species, the different cultivars showed quite different biometric, cooking and texture characteristics.
- Contribution for the characterisation of Carolino rice cultivarsPublication . Santos, Tania; Lemos, Diogo; Brites, Carla; Guiné, Raquel; Correia, PaulaRice is consumed mainly as whole grain, and quality considerations are much more important than for any other food crop. Rice grain quality preference varies from country to country and among regions. Most of the rice produced in Portugal is of the Carolino type, botanically classified as Oryza sativa ssp. Japonica. Nowadays, this rice is playing a vital role in Portuguese rice trading. Thirteen types of Carolino rice were collected and analysed for biometry characteristics, amylose content and gelatinization properties. The Carolino rices are commercially classified as long grains type-A, because they present a length higher than 6 mm and the ratio length/width lower than 3 mm), and there was observed a high variability in biometric measurements. This type of rice showed a high level of plastered area, meaning low vitrea aspect. The amylose content varied from 9.4% and 15.2%, with an average of 12.4%, meaning that Carolino rice presented low value, i.e. that the rice with low amylose content is dry, less tender and hard after cooking, also showing volume expansion and a high degree of flakiness. Carolino rice flours showed significant differences of RVA viscosity profiles. Generally they presented significant differences in the pasting temperature, but similar pasting peak temperature, 95ºC. It was also observed that the different types of Carolino rice flours showed high viscosities (minimum of 2872 cP and maximum 3797 cP), as well as great differences in breakdown and setback values.
- Contribution for the characterization of aromatic ricePublication . Santos, Tânia; Lemos, Diogo; Brites, Carla; Guiné, Raquel; Correia, PaulaRice is consumed mainly as whole grain, and quality considerations are much more important than for any other food crop. Rice grain quality preference varies from country to country and among regions. Nowadays, aromatic rice varieties are playing a vital role in global rice trading, and also in Portugal. Five types of aromatic rice were collected and analysed for biometry characteristics, amylose content and gelatinization properties. The aromatic rices are commercially classified as long grains B type, because they presented a length higher than 6 mm and the ratio length/ width higher than 3. Samples presented a high degree of whiteness (35.8-39.9). There is a stickily relationship between the total and vitrea whiteness (r2=0.95), and these parameters are related with the plaster area. Cooking quality of rice mainly depends on amylose content and gelatinization temperature. The amylose content varied from 9.8% (classified as low value) and 20.4% (classified as intermediate value), meaning that the rice with low amylose content is dry, less tender and hard after cooking, also showing volume expansion and a high degree of flakiness. When rice presents an intermediate content of amylose is moist and tender upon cooking. Aromatic rice flours showed significant differences of RVA viscosity profiles. Generally they presented significant differences in the gelatinisation temperature, but similar gelatinisation peak temperature, 95%. It was also observed that the different types of aromatic rice flours showed high viscosities, great differences in breakdown and setback values. Breakdown was positively related with the peak temperature (r2=0.733) and peak viscosity (r2=0.778), and the setback was correlated with amylose content (r2=0.846) and final consistency (r2=0.816).
- Contribution for the characterization of carolino rice cultivarsPublication . Santos, Tania; Lemos, Diogo; Guiné, Raquel; Correia, PaulaThe objective of this work was to evaluate the grain biometric characteristics of 62 rice cultivars, which cover Indica and Japonica subspecies, and different types of commercial rice like, Agulha (Indica rice cultivars), Carolino (Japonica cultivars), aromatic (basmati and thai), integral rice, risotto, glutinous (waxy), wild and parboiled rice. It was noticed that for the same group type of rice there are a great variance. Generally, the Agulha, Aromatic and Integral rices commercialized in Portuguese trade are long (length high than 6 mm and length/width ratio higher than 3) and risotto cultivars are medium size. The two studied glutinous rice cultivars presented one cultivar long and other cultivar round (length lower than 5 mm and length/width ratio lower than 1.9). All rice cultivars presented high values of white vitreous, total whiteness, and low percentage of chalky area, presenting a crystalline and translucent aspect, but there is an exception to integral rice cultivars due to absence of polish operation during the milling process and for parboiled rice cultivars due to the effects of parboiled treatment. Moreover the vitreous percentage was also high. There was a strong correlation between the white vitreous values and total whiteness.