Effect of nixtamalization process on the content and composition of phenolic compounds and antioxidant activity of two sorghums varieties

Sorghum, a competitive crop due to its agronomical advantages, has gained interest as functional food. Sorghum contains phytochemicals with health benefits and presents some antinutritional compounds such as condensed tannins (CTs). However, it is well known that CTs exhibit antioxidant capacity. This study evaluated the effect of Mexican nixtamalization on total phenols, CTs and antioxidant capacity using two varieties of sorghum. Different conditions of lime (0, 1 and 2%) and cooking time (20, 30 and 40 min) were tested to obtain the best treatment after optimization using multiple linear regression analysis, aiming to minimize the CTs content and maximize the antioxidant capacity. CTs were reduced at 27% in white sorghum and 90%, in red sorghum. Total phenols, flavonoids and antioxidant capacity had an inverse correlation with lime concentration and cooking time. The best conditions for preserving antioxidant capacity with low content of tannins were 1.13% of lime and 31.11 min cooking. The phenolic profile obtained by HPLC showed reductions in gallic and chlorogenic acids only in white sorghum, whereas catechin and quercetin decreased in both varieties. We concluded that nixtamalization effectively reduced CTs to safety intake values, allowing to preserve other phenolic compounds and antioxidant capacity.     

Quantities of phenolic compounds and their impacts on the perceived flavour attributes of rye grain

The use of whole grain rye products, beneficial to one's health, could be substantially extended if the typical intensively bitter flavour of rye could be modified without losing the characteristic rye-like flavour. The aim of the study was to evaluate the contribution of non-volatile phenolic compounds on the perceived flavour. Rye grain was milled into five milling fractions. The levels of phenolic compounds, i.e. the phenolic acids, alkylresorcinols and lignans, of the fractions were analysed and related statistically to sensory flavour profiles by partial least-squares (PLS) regression. The non-bound (free) phenolic acids are suggested to be most flavour-active. Cereal and intense flavour and aftertaste were related to vanillic and veratric acids, alkylresorcinol C_23:0, and other lignans except for pinoresinol. The perceived bitterness of the bran fractions was suggested to result from pinoresinol and syringic acid. Sinapic and ferulic acids, alkylresorcinols, except for alkylresorcinol C_23:0, and syringaresinol seemed to cause the germ-like flavour. Phenolic acids, alkylresorcinols and lignans distributed with a similar pattern in the rye grain as the flavour attributes: the phenolic compounds were clearly located in the outer bran fractions being intense in flavour, but not in the mild-tasting inner layers of the grain.     

Comparison of the effects induced by different processing methods on sorghum proteins

The effects induced by cooking, dry heating, popping, fermentation and germination on sorghum proteins were studied. Changes promoted by these processing methods were compared via sodium dodecyl sulfate polycrylamide gel electrophoresis (SDS-PAGE), in vitro protein digestibility (IVPD) assay and Fourier Transform Infrared (FT-IR).     

Pericarp thickness of sorghum whole grain is accurately predicted by NIRS and can affect the prediction of other grain quality parameters

The thickness of grain pericarp, the outer layer of the kernel, is an important breeding criterion for sorghum. This cereal is mainly used through traditional processing in family-based food systems in many regions of the world. We investigated in this study how pericarp thickness could be predicted by Near Infrared Reflectance Spectroscopy (NIRS), a fast and non-destructive measurement method that is commonly used to measure physico-chemical parameters of sorghum grains, and how this trait also influences the prediction of those parameters. We showed that, using a classification approach, it was possible to discriminate thick from thin pericarp whole grain samples with a good accuracy and that the proportion of thin and thick grains in mixed samples could also be predicted. In addition, pericarp thickness had a significant effect on the calibration performance for other grain parameters indicating that the pericarp can distort spectral information of whole grain samples. As a practical consequence, we suggest to develop separate whole grain calibration models for thin and thick pericarp samples, combined with a two-steps prediction approach to improve the accuracy of whole grain NIRS calibrations for grain quality parameters in sorghum.     

白牡丹与白毫银针香气成分的研究

白茶是中国特有的茶叶品种,文中对白茶的两个主要品种:白牡丹和白毫银针的香气成分进行分析,共鉴定出31种香气成分,其中含量较高的成分有:己醛、(E)-2-己烯醛、苯甲醛、1-戊烯-3-醇、(Z)-3-己烯醇、香叶醇、苯乙醇、芳樟醇及其氧化物等。这两种白茶的香气组成总体上具有相似性,但两者的香气组成也略有差异。白茶在存放过程中,精油含量呈降低趋势,但香气组成上仍具有明显的白茶特征。     

普洱茶与红茶的抗氧化特性比较研究

采用氯仿,乙酸乙酯,正丁醇等溶剂,分步萃取普洱茶及红茶水提物。采用化学发光法和可见分光光度法比较两类茶水提物及萃取组分在水相和油相中的抗氧化性。结果表明普洱茶在水相中的抗氧化能力无论在总体或单个组分上均略低于红茶;两类茶水提物对某些油脂具有较好抗氧化性;乙酸乙酯萃取组分对两类茶在水相中的抗氧化性起主导作用,且红茶略高于普洱茶,在油相中均无表现明显抗氧化性。     

柚子皮茶的香气组成研究

柚子皮经与绿茶和红茶加工制成柚子皮茶,其香气独特、浓郁。采用同时蒸馏萃取方法提取柚子皮和4种柚子皮茶的精油,进行气相色谱和气质联机分析,共鉴定出39种香气成分,其主要成分是柠檬烯、月桂烯、芳樟醇及其氧化物等。柚子皮中含有茶叶原有香气的多种成分,窨制后使产品的花香更明显。文中对柚子皮和4种柚子皮茶的香气成分及其含量和窨制效果也进行了对比分析。     

不同地区加工茯砖茶品质比较研究

选择不同地区有代表性的茯砖茶生产厂家,通过互换毛茶原料,以探讨茯砖茶品质形成的影响。结果表明:由陕西泾阳加工的茯砖茶(1、2、3号),口感滋味相对最纯正;由湖南益阳加工的茯砖茶(4、5、6号),口感滋味相对纯正。原料来自于陕西泾阳的(1、4、7号)茯砖茶,所含的茶多酚、黄酮和游离氨基酸含量以及水浸出物均最高;原料来自于湖南益阳的(2、5、8号)茯砖茶,所含的茶多酚、黄酮和游离氨基酸含量以及水浸出物均最低。而可溶性糖含量以原料来自于浙江武义的(3、6、9号)茯砖茶最高。表明原料不同和加工工艺不同对茯砖茶产品的品质形成有影响。     

普洱茶抗氧化特性的初步研究

本研究用不同的有机溶剂,分步萃取普洱茶的水提物,得到氯仿萃取物、乙酸乙酯萃取物、正丁醇萃取物和萃取后剩余物。采用Fe^2-H2O2-鲁米诺的化学发光法和有机自由基二苯基苦基偕腙肼（DPPH）的分光光度法,比较各提取物的清除自由基的能力。结果 提示普洱茶水提物中的乙酸乙酯萃取层组分和正丁醇萃取层组分对DPPH和羟自由基均有较强的清除能力。     

Evaluation of phenolics and antioxidant activity of black sorghum hybrids

Black sorghums possess very high levels of the rare 3-deoxyanthocyanidins which can be used as natural food colorants with health benefits. However, these sorghum genotypes have undesirable agronomic properties (i.e. high height, low yield, increased weathering). Black sorghum hybrids with improved agronomic properties were developed and their phenolic profiles and antioxidant activity were compared with black sorghum lines. Black sorghum hybrids were significantly lighter in colour than the lines (P < 0.001). All hybrids had a pigmented testa which was indicated by the presence of condensed tannins, which significantly increased total phenol levels and antioxidant activity. The 3-deoxyanthocyanidin, flavan-4-ol, and flavone levels were significantly lower in the hybrids (P < 0.001) and were strongly correlated to pericarp colour (P < 0.001). Flavanone levels were not significantly different among the lines and hybrids (P > 0.05) and pericarp colour did not affect their levels (P > 0.05). Even though the 3-deoxyanthocyanidin levels were lower in black sorghum hybrids than in the lines, the presence of condensed tannins in the hybrids significantly increased their antioxidant activity. Since 3-deoxyanthocanidin levels were dependent on pericarp colour, hybrids with increased blackness intensity should be developed to increase the stable 3-deoxyanthocyanidins.     

Comparison of sorghum and maize raw distillates: Factors affecting ethanol efficiency and volatile by-product profile

The potential of sorghum grain in the production of bioethanol was determined in comparison to maize and as an alternative to it. The effects of the raw materials, the raw material cultivars, and the fermentation process on ethanol efficiency and volatile compound profile of the raw distillates were investigated. The ethanol yield proved to be strongly determined by the variety of the raw material and by the fermentation method. The SSF method with a weight to water ratio of 1:4 proved to be the most effective for ethanol production in the case of both maize and sorghum. The highest ethanol yield at 86.94% of the theoretical value, was obtained from maize; the value from sorghum was 80.15%. The fermentation method, though not the grain cultivar, had a significant effect on the volatile compound profile of the raw distillates. The raw distillates obtained using the SSF method at a ground grain to water ratio of 1:4 had the lowest concentration of esters and aldehydes. The average content of volatile compounds in the sorghum distillates was lower than in the maize distillates. This study emphasizes the great potential of sorghum, a maize alternative, as an energy plant in the distillery.     

亚麻籽酚类化合物抗氧化和油相迁移特性研究进展

亚麻籽除了富含植物来源n-3多不饱和脂肪酸ɑ-亚麻酸外,也是木酚素、酚酸等功能性植物化合物的重要来源。本文重点综述了品种和种植区域、成熟过程、不同预处理(萌动、烘烤/焙炒、微波)及制油工艺(压榨法、溶剂法)对亚麻籽典型酚类化合物丰度、存在形态、抗氧化及油相迁移特性的影响,以期为亚麻籽油的提质制取及高值化应用提供理论依据。     

Effect of accelerated aging on maize, sorghum, and sorghum meal

Accelerated aging at 50 °C significantly affected the physical and chemical properties of sorghum and maize. Aging caused associations between starch granules, protein matrix, and cell walls. During aging, floury areas of the endosperm became more corneous; as the endosperm hardened, strong associations between starch and protein developed, causing the endosperm to fracture through endosperm cells instead of along cell walls, which is common for non-aged maize. Aging significantly decreased the pasting viscosity of starch, molecular solubility at 85 °C and the molecular weight of solubilized starch. Solubility of albumins and globulins decreased while solubility of proteins extracted by a reducing agent and/or in alkaline pH increased during aging. Decreased solubility and functionality of starch and protein in aged grain appear to be due to protein oxidation.     

Effects of infrared heating on phenolic compounds and Maillard reaction products in maize flour

Maize grains were heated by infrared radiation for 50–100 s, than flaked and milled. The output was set to 110, 115, 120 and 140 °C to determine the effect of temperature on the formation of acrylamide, 5-hydroxymethylfurfural (HMF) and furosine, as well as the level of phenolic compounds in maize flour and its total antioxidant capacity (TAC). Acrylamide and HMF levels were increased as the load of the heat treatment was increased in grains, while furosine concentration was rapidly increased to an apparent maximum (34.96 μg/g) followed by decrease during heating. Acrylamide, as well as HMF variables correlated very well with TAC of heat-treated flour (r² = 0.98 and 0.86). The process of infrared heating had a great influence on the reduction of phenolic compound contents. However, new antioxidants that were formed as a result of the Maillard reaction increased the total antioxidant capacity of heat-treated maize flour.     

Effect of genetic variation on phenolic acid and policosanol contents of Pegaso wheat lines

Total phenolic acid and policosanol contents and compositions of bran from an Italian bread wheat variety Pegaso and its 11 near-isogenic lines were measured. The near-isogenic wheat lines differed at one or more loci coding for storage proteins. The genetic variation included deletions, additions and/or combinations of variations. Almost 95% or more of phenolic acids were in the bound form. Ferulic acid was the predominant bound phenolic acid present in wheat bran samples. Other phenolic acids were p-coumaric, vanillic and syringic acids. Tetracosanol, docosanol, hexacosanol, octacosanol, tricosanol and heneicosanol were found as major policosanol compounds in their decreasing order. Highly significant genotypic differences were observed in total phenolic acid and policosanol concentrations. None of the genetic lines had higher phenolic acid contents than the parent line Pegaso, whereas some of the lines had more policosanol levels. In general, both total phenolic acid composition and contents were higher with genetic lines that varied at Glu-1 loci with 2+Dy high molecular weight glutenin subunit (HMW-GS) (Pegaso 184), variation at Gli-D2 loci (Pegaso 219) and single null A1 (variation at Gli-1/Glu-3 loci; Pegaso 30). Highest total policosanol content was observed with the double null at Glu-A1/Glu-D1 loci (Pegaso 236). These findings may lead to new opportunities for wheat breeders and eventually commercial wheat growers to promote the production of wheat with enhanced levels of health beneficial compounds.     

Changes in the phenolic compound content and antioxidant activity in developmental maize kernels and expression profiles of phenolic biosynthesis-related genes

Phenolic compounds have various nutritional and functional properties, especially antioxidant activity. The objective of this study was to explore the relationship between the phenolic compound accumulation, antioxidant property and gene expression during maize kernel development. In this study, we explored the effects of developmental stage on the accumulation of phenolic compounds and their antioxidant activities. The expression levels of genes involved in phenolic biosynthesis were also studied. The results showed that the total phenolic content (TPC) and total anthocyanin content (TAC) were gradually increased from 15 to 48 days after pollination (DAP), whereas the total flavonoid content (TFC) decreased continuously. The antioxidant activity of maize kernels was increased gradually and positively associated with TPC. ZmCHSs in flavonoid biosynthetic pathway played important roles for total flavonoid accumulation at both early and later development stages. The expression pattern of ZmANS corresponded to the accumulation of total anthocyanin during kernel development. These results revealed that developmental stage affected the accumulation of different phenolic compounds, antioxidant activity and related gene expression. The antioxidant activity of maize kernels was dependent on the total phenolic accumulation which was related to the expression profiles of the genes participated in phenolic synthesis.     

制茶工艺对名优绿茶香气品质的影响

用ＧＣ、ＧＣ／ＭＳ法分析了用同一鲜叶原料加工成的８种名优绿茶的香气组成。香型相似率分析表明,不揉捻的名茶与揉捻的名茶香型差异较大;凡经揉捻的名茶,它们之间香型比较接近,而未揉捻的名茶之间香型差异也较大,这说明加工工艺对香气形成有着重要的影响。分析结果还表明,不揉捻的名茶加工工艺（尤其是龙井茶的制作工艺）更有利于香气品质的形成。文中就制茶工艺对香气影响的原因进行了讨论     

Effect of suppressing the synthesis of different kafirin sub-classes on grain endosperm texture, protein body structure and protein nutritional quality in improved sorghum lines

To improve sorghum grain protein nutritional quality, improved sorghum lines were transformed to suppress the synthesis of different kafirin sub-classes, or backcrossed into transgenic lines with improved protein quality. Co-suppression of the alpha-, gamma- and delta-kafirin sub-classes and removal of the tannin trait resulted in transgenic sorghum lines with high cooked protein digestibility (±80%), improved Amino Acid Score (0.8) and Protein Digestibility Corrected Amino Acid Score (0.7) compared to the non-transgenic null controls (±50%, 0.4 and 0.2, respectively). These high protein quality lines had a floury endosperm. They also had modified protein body structure, where the protein bodies were irregular shaped with few to numerous invaginations and were less densely packed, with a dense protein matrix visible around the protein bodies. When fewer sub-classes were suppressed, i.e. gamma 1 and delta 2, the endosperm was corneous with normal protein body structure but the improvement in cooked protein digestibility appeared to be less. Apparently, co-suppression of several kafirin sub-classes is required to obtain high protein nutritional quality sorghum lines, but this seems to result in floury-type grain endosperm texture.     

不同形状名茶制茶工艺对茶叶品质的影响

用福鼎大白茶和云南大叶茶的一芽一叶鲜叶为原料，制成扁形、毛峰形、针形和卷曲形名绿茶。结果表明，用相同原料制成的不同形状名茶间品质差异较大，其中以扁形名茶品质最好，毛峰形茶次之，其他形状茶品质较差。生化成分分析结果也表明，扁形茶的氨基酸含量最高，酚氨比最小；福鼎种制成的扁形茶和云大种制成的毛峰形茶，其茶氨酸、天冬氨酸、谷氨酸和精氨酸等４种主要氨基酸组分及维生素含量均相对较高。表明不揉捻或轻揉捻、叶组织破损小、工艺简单、热作用时间短的扁形名茶或毛峰形名茶的制茶工艺更有利于鲜叶原料品质的发挥