Moulds and mycotoxins in rice from the Swedish retail market

A survey of moulds and mycotoxins was performed on 99 rice samples taken from the Swedish retail market. The main objective was to study the mould and mycotoxin content in basmati rice and rice with a high content of fibre. Samples of jasmine rice as well as long-grain rice were also included. The samples were analysed for their content of ochratoxin A (high-performance liquid chromatography (HPLC)), aflatoxin B₁, B₂, G₁, and G₂ (HPLC, RIDA®QUICK), and mould (traditional cultivation methods in combination with morphological analysis). The majority of samples were sampled according to European Commission Regulation 401/2006. Subsamples were pooled and mixed before milling and both mould and mycotoxin analyses were performed on milled rice. The results showed that the majority of basmati rice (71%) and many jasmine rice samples (20%) contained detectable levels of aflatoxin B₁ (level of quantification = 0.1 µg aflatoxin kg^?1 rice). Two samples of jasmine rice and ten basmati rice samples contained levels over the regulated European maximum limits of 2 µg kg^?1 for aflatoxin B₁ or 4 µg kg^?1 for total aflatoxins. Aspergillus was the most common mould genus isolated, but also Penicillium, Eurotium, Wallemia, Cladosporium, Epicoccum, Alternaria, and Trichotecium were found. The presence of Aspergillus flavus in 21% of the samples indicates that incorrect management of rice during production and storage implies a risk of mould growth and subsequent production of aflatoxin. Rough estimates showed that high rice consumers may have an intake of 2–3 ng aflatoxin kg^?1 bodyweight and day^?1 from rice alone. This survey shows that aflatoxin is a common contaminant in rice imported to Europe.     

基于食味计评价杂交籼稻食味品质

为探讨不同蒸煮条件对西南两个生态点杂交籼稻食味品质的影响,以分别种植于云南永胜和四川大邑的9 个品种中籼杂交稻为材料,利用米饭食味计分析不同蒸煮条件（7 个水米质量比（1.3∶1、1.5∶1、1.6∶1、1.9∶1、2.1∶1、2.4∶1、2.7∶1）、4 个浸泡时间（0、15、30、60 min）、3 个蒸煮时间（20、30、40 min）和3 个焖饭时间（0、15、30 min））对稻米米饭食味品质的影响。结果表明：稻米米饭的食味品质为蒸煮条件、品种、生态点及其互作效应共同作用的结果,米饭外观和食味值均受三者极显著影响（P＜0.01）;蒸煮条件与生态点、品种与生态点及三者的互作效应均极显著影响米饭食味品质（P＜0.01）。米饭食味计分析结果显示,云南永胜等光温充足稻区以水米质量比2.1∶1、浸泡30 min、蒸煮30 min以及焖制15 min蒸煮米饭的食味品质较好;四川大邑等高湿寡照稻区以水米质量比2.1∶1、浸泡15 min、蒸煮30 min以及焖制15 min蒸煮米饭的食味品质较好。9 个品种中‘内5优39’米饭食味品质最好,且在各水米质量比间变异较小,‘宜香优2115’米饭食味品质次之,而‘中优295’和‘F优498’米饭的食味品质较差,‘F优498’和‘天优华占’米饭食味品质在各蒸煮条件间变异系数较大。总体来看,云南生态点的稻米米饭外观更好,而四川生态点稻米米饭在特定蒸煮条件下食味值更高。     

STUDIES ON EVALUATION OF GRAIN QUALITY ATTRIBUTES OF SOME BASMATI AND NON‐BASMATI RICE CULTIVARS

ABSTRACT

Physical, chemical and cooking properties of some newly developed basmati and non‐basmati varieties of rice were studied, which showed significant variations within different quality parameters. The longer kernel length, intermediate amylose content, higher elongation after cooking, more water uptake ratio and strong aroma were found to be the distinctive features of evolved basmati rice cultivars like the traditional ones. There was significant correlation found between some of the important quality parameters of rice, such as paddy length breadth ratio showed a positive correlation with kernel length breadth ratio (r = 0.908), density (r = 0.801), cooked kernel length (r = 0.836) and a negative correlation with bulk density (r = −0.84). Amylose content showed a negative correlation with gel consistency (r = −0.974), solid loss in gruel (r = −0.856) while it is positively correlated with cooked kernel length (r = 0.937), elongation ratio (r = 0.829) and water uptake (r = 0.786) at 5% level of significance.

PRACTICAL APPLICATIONS

Oryza sativa has a broad range of genetic diversity within specific quality characters like physicochemical, cooking, eating and aroma. Some of these individual quality attributes got consumer's preference and became popular in different regions of the country. The quality characterization of newly developed rice cultivars from cereal chemistry approach and to find correlation between important properties is mandatory to study their quality attributes and to compare their different properties with already studied cultivars for further improvement in quality characteristics of under development varieties of rice. Thus, the present investigation reveals the morphological, physicochemical and cooking properties of some newly developed rice cultivars. These studies are of paramount importance in terms of evaluation of grain quality features of very long, long and medium grain size varieties of rice instead of focusing on only one type of variety, and thus suits different markets and consumer preferences.

     

Flavour production in plant cell cultures of basmati rice (Oryza sativa L)

Callus cultures of naturally flavoured rice (Oryza sativa var 370) called basmati were obtained on Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid and kinetin. There was a perceptible basmati flavour in fresh callus. The volatile flavour components of basmati rice and callus were obtained by steam distillation-solvent extraction and were analysed on GC-MS. A qualitative comparison of volatile flavour components of callus cultures and natural basmati rice was also made. The results show the presence of 29 major compounds in rice and 23 in callus. The identified compounds include hydrocarbons, ketones, aldehydes, alcohols and esters. This demonstrated the potential of callus of basmati rice for flavour development.     

Differences in physicochemical properties of kernels of two rice cultivars during grain formation

BACKGROUND: Rice varieties with similar apparent amylose content may have different grain qualities. The development of rice quality is a dynamic process that occurs with the formation of rice kernels. In this study, physicochemical properties during the grain formation period were investigated to interpret differences in grain quality between two non‐waxy rice cultivars, Wuyujing3 and 30you917, with similar apparent amylose content. RESULTS: There were significant differences in dynamic changes in 1000‐grain weight, amylose content and pasting and thermal properties during grain formation of the two cultivars. The difference in their apparent amylose contents from 5 days after anthesis (DAA) to 15 DAA was significant, except in the late grain‐filling stage. Wuyujing3 showed a slower increase in 1000‐grain weight than 30you917 from 10 to 25 DAA. The transition temperatures (T_o, T_p and T_c) of developing grain flour of Wuyujing3 were higher than those of 30you917 during the grain formation period. Wuyujing3 showed greater stickiness (higher breakdown and peak viscosity and lower positive setback) than 30you917 according to Rapid Visco Analyser (RVA) profiling. CONCLUSION: The results suggested that the differences in cooking and eating quality parameters of the two mature rices were determined by the differences in grain filling and the dynamic changes in the main rice quality components such as amylose content, grain weight and differential scanning calorimetry and RVA properties, which will help cultivators understand the physical basis of rice quality development. Copyright © 2011 Society of Chemical Industry     

Physicochemical,Textural, Pasting,and In Vitro Digestion Properties of Some Basmati and Non-Basmati Rice Cultivars

Grain quality attribute tests based on physicochemical, textural, pasting, and in vitro digestion properties of eight different rice cultivars were studied. Basmati varieties showed higher values of amylose content, iodine absorption, blue value, hardness, cohesiveness, pasting temperature, and set back, whereas swelling power, solubility, adhesiveness, peak viscosity, and breakdown values were found to be higher in non-basmati varieties. The release of maltose from basmati rice flour (23.12–25.86 mg/g rice flour) was found to be slower as compared to non-basmati ones (27.43–28.36 mg/g rice flour). Amylose content showed significant correlations with different quality parameters at 5% level of significance.     

两种香米在不同温度储存过程中理化性质和食用品质的变化

以‘稻花香二号’和‘茉莉’大米为对象,从理化性质、质构特性、蒸煮特性和糊化特性4 个角度分析了香米在15 ℃、室温（约20～25 ℃）和37 ℃储存过程的品质变化,以期为优质大米的实际储存和流通过程提供理论依据。结果表明,在不同温度储藏期间,香米的各品质特性均发生明显改变,且温度越高,变化幅度越大。其中,‘茉莉’大米在储存过程中的水分质量分数、蛋白质量分数、巯基质量分数、L*值、a*值、米汤pH值的下降幅度以及硬度的增加幅度均大于‘稻花香二号’大米。‘稻花香二号’大米的直链淀粉质量分数、b*值和膨胀率增加幅度均大于‘茉莉’大米。香米在储藏期间,黏着性不断下降,而吸水率和糊化温度不断提高。香米在15 ℃条件下回复性变化不显著,而在其他温度条件下显著上升（P＜0.05）。‘稻花香二号’大米的弹性总体变化不显著,而‘茉莉’大米呈下降趋势。‘茉莉’大米在储藏期间咀嚼性更稳定。结合咀嚼性、峰值黏度和崩解值分析,37 ℃分别储藏120 d和180 d后,‘稻花香二号’大米和‘茉莉’大米的食味性达到最佳,且储藏结束后‘茉莉’大米的食味性高于‘稻花香二号’大米。     

Functional and thermorheological properties of rice flour gels for gluten-free pasta applications

Based on the European Commission directives on circular economy, this work explores the functional and thermorheological properties of rice flour from broken kernels, a by-product from the rice industry, in order to evaluate its possible use in food applications, back into the value chain. Chemical and hydration properties of two rice varieties (Guiana – Indica spp, Ariete – Japonica spp) were accessed, as well as the impact of the rice variety on the texture and viscoelasticity of rice flour gels (6–26%). Both rice varieties presented statistically different physicochemical properties (protein, lipid and amylose contents), and hydration properties that support the distinct texture and rheology behaviour of gels obtained. Rheology results suggested the formation of a gel-network structure with high frequency dependence, especially at lower rice concentrations. Texture results suggest that both rice varieties could be suited for development of gluten-free products that require pre-gelatinised starch, such as pasta. The effect of gelatinised rice flour (10–25%) and gelatinised flour/rice flour ratio (40:60, 50:50, 60:40) on the physical properties and cooking quality of pasta were assessed. Better overall cooking quality and texture properties were obtained for the formulation with 20% gelatinised rice flour and 50:50 rice gel:rice flour ratio.     

Effects of an exogenous xylanase gene expression on the growth of transgenic rice and the expression level of endogenous xylanase inhibitor gene RIXI

BACKGROUND: Xylanases have attracted considerable interest in recent years owing to their various applications in industry and agriculture. The use of transgenic plants to produce xylanases is a less expensive alternative to biotechnological programmes. The aim of this study was to elucidate whether introducing a foreign xylanase gene ATX into rice had any adverse effect on plant growth and development. RESULTS: A recombinant xylanase gene ATX was introduced into rice variety Zhonghua 11 through Agrobacterium‐mediated transformation. The T₂ generation of transgenic rice was compared with the control (non‐transgenic plants). Exogenous xylanase gene ATX was expressed in rice, and all examined transgenic lines exhibited xylanase activity. The transgenic lines (T₂, ‘X1‐3’ and ‘X2‐5’) appeared to grow and develop normally. There were no differences in net photosynthetic rate between transgenic rice lines (‘X1‐3’ and ‘X2‐5’) and wild type (WT) rice plants at the heading/flowering stage. Xylanases are key enzymes in the degradation of plant cell walls. Cell wall composition analysis showed that that there were no changes in cell wall polysaccharides in the root apex but some alterations in leaves in transgenic rice plants. The results also showed that the expression of exogenous xylanase gene ATX in rice would increase the expression of endogenous xylanase inhibitor gene RIXI, which could play a role in plant defence. Thus the stress resistance of transgenic rice plants might be improved. CONCLUSION: Exogenous xylanase gene ATX could be successfully expressed in rice, and the exogenous protein had no apparent harmful effects on growth and development in transgenic rice plants. Copyright © 2012 Society of Chemical Industry     

不同品种大米口感品质分析

以不同品种大米为研究对象,采用模糊感官评价结合质构仪分析及电子舌技术,对大米米饭口感品质 进行比较分析,建立一种米饭口感品质评价的方法。结果表明：模糊感官评价和质构特性分析中大粒香米饭口 感最佳,内优5H25米饭口感最差,大粒香、大粒溪香、金麻粘3 种米饭感官评分较接近且质构特性基本无显著差 异（P＞0.05）。通过主成分分析,电子舌能很好地区分不同品种大米原料及米饭,其结果与模糊感官评价一致。 通过偏最小二乘回归分析建立米饭滋味评价模型,相关系数达到0.954 06,能很好地预测不同品种米饭的滋味。因 此,在大米口感品质评价中,感官评定结合电子舌的分析方法更易获得准确、可靠的结论。     

Evaluation of Texture Differences among Varieties of Cooked Quinoa

Texture differences of cooked quinoa were studied among 13 different varieties. Correlations between the texture parameters and seed composition, seed characteristics, cooking quality, flour pasting properties, and flour thermal properties were determined. The results showed that texture of cooked quinoa was significantly differed among varieties. ‘Black,’ ‘Cahuil,’ and ‘Red Commercial’ yielded harder texture, while ‘49ALC,’ ‘1ESP,’ and ‘Col.#6197’ showed softer texture. ‘49ALC,’ ‘1ESP,’ ‘Col.#6197,’ and ‘QQ63’ were more adhesive, while other varieties were not sticky. The texture profile correlated to physical?‐chemical properties in different ways. Protein content was positively correlated with all the texture profile analysis (TPA) parameters. Seed hardness was positively correlated with TPA hardness, gumminess, and chewiness at P ≤ 0.09. Seed density was negatively correlated with TPA hardness, cohesiveness, gumminess, and chewiness, whereas seed coat proportion was positively correlated with these TPA parameters. Increased cooking time of quinoa was correlated with increased hardness, cohesiveness, gumminess, and chewiness. The water uptake ratio was inversely related to TPA hardness, gumminess, and chewiness. Rapid Visco Analyzer peak viscosity was negatively correlated with the hardness, gumminess, and chewiness (P < 0.07); breakdown was also negatively correlated with those TPA parameters (P < 0.09); final viscosity and setback were negatively correlated with the hardness, cohesiveness, gumminess, and chewiness (P < 0.05); setback was correlated with the adhesiveness as well (r = ?0.63, P = 0.02). Onset gelatinization temperature (T_o) was significantly positively correlated with all the texture profile parameters, and peak temperature (T_p) was moderately correlated with cohesiveness, whereas neither conclusion temperature (T_c) nor enthalpy correlated with the texture of cooked quinoa.     

不同烹煮方式对米饭食味品质的影响

以4种市售大米为研究对象,利用质构仪、气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)及感官评价等检测和评价手段,对不同烹煮方式的米饭进行基本蒸煮品质、质构特性以及风味物质等食味品质的评价,并探究其与感官评价的相关性。旨在探究不同大米品种(粳米和籼米),以及不同蒸煮工艺(高压烹煮、电饭锅烹煮、微波烹煮和电蒸锅烹煮)对米饭食味品质的影响,寻找一种能够综合评价米饭食味品质的方法,为米饭的制作及米饭食味品质的改善提供理论参考。结果表明:经高压烹煮后的米饭吸水率、膨胀率、碘蓝值均高于其他方式,且米饭硬度小,弹性和黏性较大,感官品质评价最优,而微波烹煮米饭食味品质最差。米饭膨胀率与感官评价中米饭的滋味和形态呈显著正相关(P0.05,P0.01),硬度与口感呈极显著负相关(P0.01),弹性与米饭形态呈极显著正相关(P0.01)。此外,米饭风味物质分析表明经高压烹煮和电饭锅烹煮的米饭,醛、醇、酮等主要的米饭风味物质含量和种类均高于其他烹煮方式,且因品种不同大米的香气有所差异。     

Effects of potato starch on the characteristics,microstructures and quality attributes of indica rice flour and instant rice noodles

The effects of partial replacement (0%–20%, w/w) of rice flour by potato starch (PS) on the physicochemical properties, microstructures, texture and in vitro digestibility of indica rice flour (IRF) and instant rice noodles (IRN) were systematically investigated. Accordingly, the addition of PS significantly increased the peak viscosity (2876.00–3221.00 mPa·s) and tan δ values (0.14–0.22) but lowered the setback values (2169.00–1036.50 mPa) of the pastes. Rice noodles with 5%–15% PS (PS and IRF at the mixing ratios of 5:95, 10:90, 15:85 and 20:80, respectively) addition exhibited modulated appearance and textural properties. The mutually exclusive phosphate groups of PS facilitated the expansion of starch granules, contributing to the formation of more compact microstructure and higher-ordered crystalline structures (confirmed by scanning electron microscope and X-ray diffraction), endowing rice noodles with better cooking and digestive attributes, and visibly increased slowly digestible starches content (26.09%–31.34%). The quality attributes of rice noodles could be accurately predicted by the physicochemical properties of rice flour referring to Pearson’s correlation analysis. The study demonstrates that the blending of PS is both an effective and economical pathway in improving the nutritional and textural properties of IRN.     

Studies on Transfer of Bacterial Blight Resistant Genes of Indica–Japonica Crosses in Oryzae sativa L

A rice ( Oryzae sativa L) indica bacterial blight (BB) resistant variety DV85 was crossed with japonica wide compatibility varieties (WCVs), and results showed that their compatibilities were very poor and the resistant genes in F ₂ significantly biased away from normal segregated values by the χ² test at the 1% level. This distorted segregation was not related to spikelet fertility, panicle length, grains per panicle and 1000-grain weight by correlation analyses. Four resistant derived lines to BB have been obtained by an anther culture technique. ZD92147 was resistant to Chinese races 1, 3, 4 and Philippine races 1–5 and moderately resistant to Chinese races 2, 5 and Philippine race 6. ZD92152 was resistant to Chinese races 1, 4, Philippine races 1, 2, 3, 5 and moderately resistant to Chinese races 2, 3 and Philippine races 4 and 6. Their resistances equalled or exceeded the level of DV85 and were much better than check variety ‘Xiushui 11’. The F ₂ of japonica-biased resistant plants of japonica WCVs×DV85 was anther cultured, and results showed that it is a more convenient and effective breeding method than ordinary breeding methods to transfer BB resistant genes in wide crosses. The four derived lines indica–japonica behaviours were also studied. ZD92147 and ZD92149 belong to japonica, ZD92150 belongs to the indica–japonica middle type, while ZD92152 belongs to indica.     

Thermal processing of rice grains affects the physical properties of their pregelatinised rice flours

Waxy, low- and high-amylose rice were cooked at different temperatures (50, 70, 90 °C) for different times (15, 30, 45 min). The microscopic, rheological and gel textural properties of resultant flours were investigated. There was a coarser and discontinuous honeycomb-like structure with formation of pores in rice flour with greater cooking degree. T_Gʹmax was positively correlated with cooking temperature and time. As cooking temperature increased, the Gʹ values of pastes first increased and then decreased, whereas the opposite trend was observed for tan δ. Meanwhile, increased cooking temperature was responsible for increases in n values and caused drops in K and hysteresis area. As cooking time increased, the hardness and gumminess of gels from rice cooked were increased at lower temperature, but were decreased at higher temperature. Overall, cooking temperature was more important in determining the processing properties of rice flours than cooking time.     

基于主成分分析和聚类分析综合评价蒸谷米的品质特性

为探讨蒸谷米的品质并建立其评价体系,本试验选取12个不同品种的稻谷原料制备蒸谷米,并对其碾磨品质、外观品质、营养品质、食味品质和糊化特性的品质指标进行测定分析,考察不同品种稻谷制得的蒸谷米各项品质指标之间的差异性。同时,采用主成分分析法和聚类分析法对蒸谷米的品质进行综合性评价并建立蒸谷米品质评价模型。结果表明,不同品种稻谷制得的蒸谷米各项品质指标之间均存在差异性（P<0.05）,且品质指标间变异系数各不相同,说明蒸谷米在不同品质性状之间呈现不同程度的变化。由主成分分析发现23个反映不同品种稻谷制得的蒸谷米品质的指标可以用6个主成分表示,其累积方差贡献率为91.083%;根据聚类分析结果可知,爆腰率、黄米粒、外观、蛋白质、崩解值、峰值黏度、最终黏度和回生值8个品质指标可以用来综合评价蒸谷米品质的优劣。12个不同品种稻谷制得的蒸谷米中,“玉针香”的品质最佳,“大粒香”的品质最差,其次为“粤丰B”。主成分分析结合聚类分析综合评价方法可为不同品种稻谷制备蒸谷米的品质评价提供参考,并为蒸谷米专用稻的选育及蒸谷米资源的开发应用奠定理论依据。     

QUALITY EVALUATION OF QUICK COOKING BASMATI RICE

Basmati rice is valued for its flavor and long, bold grains. Traditionally this variety of rice demands a special cooking method of pre‐soaking, boiling with an optimum amount of water and spreading for cooling. The technology to develop Quick Cooking Rice (QCR) hitherto used for nonscented rice has been extended to basmati rice, and the effect of processing on the cooking quality of basmati QCR was tested by sensory profiling, complemented by GC head‐space volatiles for analysis of the basmati flavor released during rehydration. The performance of processed and unprocessed basmati rice is described here.     

Cassava varietal screening for cooking quality: Relationship between dry matter,starch content,mealiness and certain microscopic observations of the raw and cooked tuber

Thirteen cassava (Manihot esculenta L Crantz) varieties from three successive annual harvests were screened for the mealiness of the cooked tuber, and the elasticity and smoothness of the pounded paste. Six were selected for further studies based on their mealiness and the starch and dry matter contents were determined. The diameter of the starch granules of the selected varieties and those of an irradiated M₁ V₂ population were measured. Microscopic examinations of the raw and cooked cells of the irradiated M₁ V₂ population were made. Correlations among all the parameters were studied. Varietal and seasonal differences in cooking quality were observed. There was no consistent relationship between mealiness of the boiled tuber and the elasticity and smoothness of the pounded paste. Varieties that were mealy were high in dry matter and starch content. The starch granules of mealy varieties were larger than those of nonmealy ones. There were no differences between mealy and non-mealy varieties in the arrangement of the cells or ‘cell condition’, of the raw tubers. However, the cells of the cooked tubers were held less cohesively, ie there was more ‘cell disorganisation’, in mealy varieties than in non-mealy ones.     

原料大米对成品黄酒抗氧化性的影响

以泰国香米、上海武育米、长粒香米、东北大米、扬州大米和扬州糯米为研究对象,考察其酿造特性和抗氧化性;分别以上述6种大米为原料酿制黄酒,研究主发酵期间醪液抗氧化能力的动态变化趋势,评估成品黄酒的品质和抗氧化性。结果显示,原料大米及相应成品黄酒中的多酚对其抗氧化活性具有重要影响,多酚含量越高,抗氧化活性就越强;以扬州大米为原料酿制的黄酒的抗氧化活性最强,且品质优良。研究结果表明,扬州大米可以作为糯米的替代品或作为配料用来酿制具有抗氧化活性的黄酒。     

Variation among physical,chemical and technological properties in three Sicilian cultivars of Chickpea (Cicer arietinum L.)

Three Sicilian chickpea cultivars (‘Calia’, ‘Etna’ and ‘Principe’) were evaluated for physical, chemical and technological properties. Whereas no substantial differences were ascertained on seeds chemical composition, the cultivars greatly differed in terms of seed size, specific surface area (SSA) and seed coat incidence. These last two properties affected the technological properties of the seeds. In particular, a high SSA (‘Calia’) contributed to a faster softening, whilst a great coat thickness (‘Etna’) delayed both hydration and softening rate. The time required to obtain an acceptable firmness (cooking time) was greatly reduced by presoaking the seeds in salt solution (0.5% NaCl or NHCO₃). ‘Calia’ required the lowest cooking time when soaked in distilled water or in 0.5% NaCl. Presoaking seed in NaHCO₃ allowed halving the cooking time in all cultivars.