Rapid wetting method to reduce cyanogen content of cassava flour

In 2005 a simple wetting method was developed that reduced total cyanide content of cassava flour 3–6-fold. The method involved spreading wet flour in a thin layer and standing in the shade for five hours to allow evolution of HCN gas. We found that breakdown of linamarin catalysed by linamarase to acetone cyanohydrin, followed by its spontaneous decomposition to HCN and acetone was greatly increased by standing the wet flour in the sun. Treatment for two hours in the sun gave the same amount of total cyanide remaining as five hours in the shade. This rapid treatment in the sun may be more acceptable to rural women in Democratic Republic of Congo, than five hours in the shade. The two methods are offered as alternatives for use in rural Africa. With adequate linamarase present the residual cyanogen remaining after the wetting treatment was acetone cyanohydrin.     

Influence of processing, storage time, and pasteurisation upon the tocopherol and amino acid contents of treated green table olives

The effect of the processing system, storage time, and pasteurisation on the contents of tocopherols and individual amino acids was determined in alkali-treated green table olives. Olives were processed following three different systems (Spanish-style, short-process, and Picholine-style), together with two modified preparations of Spanish-style (without-washing process and olives packed with fermentation brine). Processing and pasteurisation had no effect on the -tocopherol and -tocopherol contents, but significant losses of both tocopherols were found after 12 months of storage. Calculation of protein quality of each product was made from its amino acid composition. The chemical score of treated green table olives, evaluated using the FAO reference protein for adults, ranged from 46 to 60%, the limiting amino acid being lysine. With the exception of lysine, amino acids can be considered to be stable during green olive processing, storage, and pasteurisation.     

不同品种桑葚与桑叶中氨基酸含量差异研究

目的比较不同品种果桑中游离氨基酸总量、必需氨基酸及药用氨基酸含量差异。方法以6个品种果桑(中葚1号、红果3号、831A、四季果桑、大白葚、江米果桑)的桑葚果实和桑叶为检测样品,利用全自动氨基酸分析仪分别测定成熟期桑葚和桑叶中游离氨基酸含量。结果 6个供试品种桑葚和桑叶均含有19种游离氨基酸,桑叶中氨基酸含量明显高于桑葚中氨基酸含量,紫色果实品种的叶片中氨基酸总量高于白色果实品种,紫色果实品种果实中的氨基酸总量又都低于白色果实品种,两者呈相反趋势。结论不同品种桑葚与桑叶中氨基酸存在较大差异。     

水浮莲叶氨基酸及微量元素的测定

采用高效液相色谱法和原子吸收法对水浮莲叶中的氨基酸和微量元素进行测定,测得水浮莲叶中17种氨基酸和8种微量元素。结果表明:水浮莲叶中氨基酸总含量(为58.288mg/g)及必需氨基酸含量(为28.905mg/g)皆较高,且富含微量元素。     

Retention of carotenoids in cassava roots submitted to different processing methods

Large genetic variation in carotenoid content has been reported after screening roots from thousands of cassava genotypes. Moreover, these pigments have to withstand different processing methods before cassava is consumed. True retention of β‐carotene from cassava roots that had been boiled, oven‐dried, sun‐dried, shadow‐dried, or used for gari preparation was measured. True retention was also measured after storing for 2 or 4 weeks some of the products of these processing methods. Oven‐drying, shadow drying and boiling retained the highest levels of β‐carotene (71.9, 59.2 and 55.7%, respectively) and gari the lowest (about 34.1%). Higher retention was observed when dried roots were kept as chips rather than as flour. Storage of flour packed in plastic bags under vacuum unexpectedly resulted in higher losses than storage of flour packed in plastic bags without the application of vacuum. Losses were higher during the first 2 weeks and tended to be considerably lower during the second 2 weeks of storage. Copyright © 2006 Society of Chemical Industry     

Effect of differential processing methods on L-Dopa and protein quality in velvet bean, an underutilized pulse

Different accessions of velvet bean were subjected to traditional and technological processing methods like soaking, germination, microwave cooking, dry heating and γ-irradiation with a view to assess the extent to which the L-Dopa gets reduced. Furthermore, the impact of certain processing methods on the levels of total protein and essential amino acid profiles was also assessed. The percentage of L-Dopa in the raw seeds ranging from 5.63 (Mundanthurai white-coloured) to 4.44 g/100 g DM (Mundanthurai black-coloured). The processes of germination (120 h) and soaking in Ca(OH)₂ solution effected significant reduction in the content of L-Dopa (i.e., from 34.8% to 58.4%; and 5.6% to 54.5%, respectively). On the contrary, dry heat treatment and microwave cooking appeared to be less effective in reducing the contents of the same. While, γ-irradiation at 10 kGy seemed to be more effective in reducing the L-Dopa than at 5 kGy. Soaking in calcium hydroxide, microwave cooking and γ-irradiation had little impact on the profiles of essential amino acids except cystine (which was completely deactivated) in both the accessions of Thachenmalai. Nonetheless, in Thachenmalai (black-coloured) accession upon soaking in calcium hydroxide, the levels of valine, phenylalanine, tyrosine, isoleucine and histidine were found to be comparable with FAO/WHO (1991) requirement pattern. To sum up, of the various processing methods employed in the present study, germination and soaking in calcium hydroxide were effected greater reduction in L-Dopa content and caused minimum effect on the profiles of essential amino acids of seed proteins.     

发展特色烟叶是重点骨干品牌和优质烟区实现共赢的合作平台

分析了特色优质烟叶对我国卷烟产品结构提升和重点骨干品牌发展的重要性。并根据发展特色优质烟叶和优化烟叶资源配置的研究实践,从卷烟工业企业和产区共同发展的需求出发,提出发展特色优质烟叶的工作思路,并在理论和技术层面对工商联办特色优质烟叶基地提出具体建议和思路。     

Simple procedures to remove mimosine from young leaves, pods and seeds of Leucaena leucocephala used as food

The effect of boiling and soaking in water on the mimosine and protein contents of young leaves, pods and seeds of the tropical leguminous tree Leucaena leucocephala (leucaena) was investigated. It was observed that the soluble protein content in leucaena tissue was overestimated because of the presence of mimosine. A more accurate method of determining the soluble protein content in leucaena tissue containing mimosine was developed and used in this study. It was found that boiling removed mimosine from young leaves, pods and seeds of leucaena but it also reduced the amount of soluble protein significantly. Soaking in water for 24 h eliminated 97% of mimosine from young leaves, pods and split seeds of leucaena, and up to 20% of mimosine from the whole young seeds without significantly reducing the soluble protein content.     

Effect of technological processing and preservation method on amino acid content and protein quality in kale (Brassica oleracea L. var. acephala) leaves

BACKGROUND: The aim of the investigation was to evaluate the level of amino acids and quality of protein in raw and processed kale leaves. RESULTS: In all samples the dominant amino acids in g kg^?1 raw matter were glutamic acid, aspartic acid and proline. In raw kale leaves the limiting amino acids were lysine, isoleucine and cystine with methionine, and in the remaining products also valine and leucine. Blanched kale leaves contained 88% of the amino acid content in raw leaves, 76% in cooked leaves, and 69–77% and 71–72% of initial levels in frozen and canned products, respectively. In raw, blanched and cooked leaves essential amino acids comprised 44%, 44% and 47%, respectively, of total amino acids; in frozen and canned leaves the proportions were 46% and 44%, respectively. The essential amino acid index was 97 for canned products, 100–109 for frozen leaves, and 117 for raw kale leaves. CONCLUSION: Raw and processed (blanched or cooked) kale leaves are a good source of amino acids. Copyright © 2011 Society of Chemical Industry     

不同干燥方法对酸枣叶中核苷类、氨基酸类及黄酮类成分的影响

为研究不同干燥方法对酸枣叶干燥过程中内在质量的影响,采用UPLC-TQ MS法和HPLC法分别建立酸枣叶中20种核苷类和23种氨基酸类,以及黄酮类成分芦丁的分析方法,并探索不同干燥方法对酸枣叶中上述组分组成及含量的影响。研究结果表明本研究所建立的分析方法简便、准确可靠;所有样品均富含核苷类、游离氨基酸类及黄酮类成分芦丁,其中核苷类成分以磷酸化产物如胞苷-5’-单磷酸、腺苷-5’-单磷酸、鸟苷-5’-单磷酸含量相对较高,游离氨基酸类成分以脯氨酸、酪氨酸、γ-氨基丁酸含量相对较高;且所有干燥加工后样品其上述成分含量均总体高于新鲜样品。依据各样品中所测定成分的含量,采用TOPSIS分析法,对不同干燥方法干燥样品的内在质量进行了综合评价,结果显示以自然晒干样品和40℃热风干燥样品品质较优,而新鲜样品及70℃热风干燥样品品质较差。以上研究结果为酸枣叶产地干燥加工过程适宜干燥工艺的确定提供了数据支撑,也为叶类药材的干燥加工提供了借鉴。      

海拔与树龄对五峰县茶叶生化成分的影响

摘 要：目的 探究海拔、树龄对湖北五峰县夏季茶树鲜叶中主要生化成分的影响。方法 以湖北五峰县海拔217~934 m之间采集的14份茶树一芽二叶鲜叶样本为研究对象,对其茶多酚、游离氨基酸、咖啡因以及部分儿茶素单体含量进行测定,并结合相关性分析和主成分分析来分析其变化规律。结果 茶多酚在海拔217~820 m范围内随海拔上升而升高,树龄10年时含量最低;咖啡因与海拔呈极显著正相关,与树龄无显著相关性;游离氨基酸含量在海拔610 m处达到最大值;酚氨比结果显示,树龄小于15年且海拔610 m以下的茶叶可能更适合制作绿茶,710 m以上的可能更适合制作发酵茶;主成分分析结果显示,提取出前2个主成分,累计方差贡献率达66.21%,可以将14份茶树样本以500 m海拔为界限大致分为两类,且500 m海拔以上的茶树鲜叶中表儿茶素没食子酸酯等儿茶素类物质的含量更高。结论 不同海拔和树龄的茶叶各生化成分之间有不同程度的差异,研究不同条件下茶叶成分含量为五峰县夏季茶树鲜叶的利用和加工提供了一定的数据支持和理论依据。     

Carotenoids in cassava: Comparison of open-column and HPLC methods of analysis

Cassava leaves and tubers from six cultivars were analysed for carotenoids by both open-column chromatography and high-performance liquid chromatography (HPLC). The major carotenoids of leaves were the non-vitamin A carotenoid lutein (86-290 mg kg^?1 fresh weight (FW)) and the pro-vitamin A carotenoid β-carotene (13-78 mg kg^?1 FW). Immature leaves contained less than mature leaves. Tubers contained 0.1-3 mg kg^?1 FW of β-carotene and 0.05-0.6 mg kg^?1 FW of lutein. Carotenoids present in small amounts included α-, γ-, and §-carotenes and β-cryptoxanthin and others were separated and partially identified. Yellow tubers contain much more β-carotene than white tubers and cassava is a good source of pro-vitamin A carotenoids compared with other root crops. Both methods gave similar results for β-carotene and lutein, but the open-column method did not allow separation and quantitation of carotenoids present in small amounts. HPLC separated many carotenoids, but most peaks could not be identified for lack of reference compounds. A great advantage of open-column chromatography for developing countries is its use of simple equipment and readily available reagents and solvents compared with HPLC, which requires complex equipment needing careful maintenance and expensive solvents. The open-column method is more labour intensive but this is not a constraint in developing countries.     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

忍冬茶及其加工过程中氨基酸和微量元素分析

目的:考察忍冬茶及其加工过程中氨基酸、微量元素含量的变化情况。方法:采用L-8800型全自动氨基酸分析仪分析忍冬茶及其加工过程中氨基酸种类及其含量的变化情况;采用火焰原子吸收光谱法测定铜、锌、铁等9种微量元素的含量。结果:忍冬茶中含有17种氨基酸且含量丰富,加工前后17种氨基酸的种类没有变化但含量都有所增加;加工后微量元素锌、铁、锰的含量增加,铜、铅、铬、镍、砷的含量降低。忍冬茶经过冲泡后有害金属元素铅、镉、镍、砷含量均符合GB2762—2005《食品中污染物限量》中规定的标准。结论:忍冬茶的加工过程增加了氨基酸和多种有益微量元素的含量,降低了多种有害金属元素的含量,有害金属元素含量均符合GB2762—2005《食品中污染物限量》中规定的标准,表明忍冬茶加工工艺可行,饮用安全。      

Identification of phenolic compounds and their relationships to in-vitro digestibility of sorghum leaves from bird-resistant and non-bird-resistant varieties

Soluble phenolics in leaf blades and sheaths from the crop residues of 24 sorghum varieties were studied. Apigenin, luteolin, apigenin and luteolin 7-O-glucosides, p-coumaric acid, butin and apigeninidin were identified. This is the first report of butin in sorghum tissues. Derivatives of the following compounds were also detected but not characterised further: apigeninidin, luteolinidin, chalcone, flavanone and/or dihydroflavonol, cinnamic acid, apigenin and luteolin. The composition of phenolics was clearly different between leaf blades (LB) and sheaths (LS), and also between leaf sheaths of bird-resistant (BR) and non-bird-resistant (NBR) varieties. Routes of flavonoid biosynthesis in BR and NBR varieties appear to diverge at the flavanone/dihydroflavonol level. Several negative correlations were found between HPLC peaks and in-vitro digestibilities, ie true dry matter and neutral-detergent fibre digestibility. These were highly significant with butin and significant with several luteolin derivatives but only with one apigenin derivative. Butin in turn was highly negatively correlated with colorimetric measurements of 3-desoxyanthocyanidins. This may suggest that butin—rather than the 3-desoxyanthocyanidins as previously reported—is implicated in reducing dry matter digestibility. Selecting varieties low in luteolin derivatives and butin and rich in apigenin should enhance the digestibilities of sorghum crop residues.     

Reactions of chickpea to water stress: yield and seed composition

Drought after podding is a common feature of chickpea production in south‐western Australia. We studied the effect of water stress, imposed after podding, on yield and on the accumulation of amino acids and soluble sugars in seeds. Although terminal water stress decreased the total plant dry mass and seed yield by 23% and 30% respectively, it had no effect on the mass of individual pods and seeds which remained on the plant after the imposition of stress treatment. The deleterious effect of water stress on yield was due to increased pod abortion and a decrease in pod formation. Water stress improved the seed's nutritive value in terms of higher accumulation of soluble sugars, amino acids and proteins. © 2001 Society of Chemical Industry     

Chemical composition and antioxidant activity of tronchuda cabbage internal leaves

A phytochemical study was undertaken on the internal leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC). Seventeen phenolic compounds were characterized and quantified by reversed-phase HPLC-DAD-ESI-MS ⁿ and HPLC/DAD, respectively: quercetin 3-O-sophoroside-7-O-glucoside, 3-p-coumaroylquinic acid, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-(caffeoyl)-sophoroside-7-O-glucoside, sinapoyl gluc-oside acid, kaempferol 3-O-(sinapoyl)-sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl)-sophoroside-7-O-glucoside, kaempferol 3-O-(p-coumaroyl)-sophoroside-7-O-glucoside, 4-p-coumaroylquinic acid, sinapic acid, kaempferol 3-O-sophoroside, 3 isomeric forms of 1,2-disinapoylgentiobiose, 1-sinapoyl-2-feruloylgentiobiose, 1,2,2-trisinapoylgentiobiose and 1,2′-disinapoyl-2-ferul-oylgentiobiose. Seven organic acids (aconitic, citric, ascorbic, malic, quinic, shikimic and fumaric acids) were also identified and quantified. The hot water extract of tronchuda cabbage internal leaves was investigated for its capacity to act as a scavenger of DPPH^• radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid), exhibiting antioxidant capacity in a concentration dependent manner against all radicals.