Investigations into flavouring compounds formed in roasted brown mustard (Brassica juncea LINN.)

Roasted brown mustard seeds (Brassica juncea LINN.) form an important condiment. Whereas the flavour of unroasted mustard seed powder is mainly due to isothiocyanates, their roasting brings about changes in its flavour. Twenty four compounds have been identified in roasted mustard which are responsible for its flavour, these include nine carbonyls, six pyrazines, two thiophenes, two amines, one nitrile, two isothiocyanates, one thiocyanate and one alkyl sulphide. The carbonyls were resolved as 2,4-DNP-hydrazones by TLC. The quantity of total carbonyls per 5 kg in roasted mustard was 105 mg as compared to 26 mg in unroasted mustard. Non-carbonyls were separated both by GLC and TLC. By GLC these were characterised by their specific retention times on different columns and on TLC by their R and specific colour reactions. They were further confirmed by their IR spectra. Their quantitative estimation and mechanism of formation is discussed.     

Aflatoxin contamination in mustard (Brassica juncea) in relation to agronomic practices

Aflatoxin contamination in two varieties of mustard (Brassica juncea L), Varuna and BR-40, sown on three planting dates (1, 15 and 30 November) under two different cropping patterns, viz monocropping and mixed cropping (along with the UP-262 variety of wheat), was examined in rabi (winter) crops of 1987–1988 and 1988–1989. Analysis of variance showed a significant effect of planting date and cropping pattern as well as a combined effect of planting date × cropping pattern. Delayed planting (30 November) resulted in a very high level of aflatoxin contamination. The level of aflatoxin was low when mustard was cultivated along with wheat (mixed cropping). Varuna was more susceptible to aflatoxin than BR-40. The maximum number of fungi was recorded in mixed cropping samples.     

湖南芥菜腌制发酵过程中的菌相变化规律

从动态角度研究湖南芥菜发酵过程中6 种菌相阶段性变化,为其实现从自然发酵到人工发酵提供科学依据。结果表明：芥菜发酵主要分为3 个阶段。第1阶段发酵液pH＞5.0,细菌总数、肠道杆菌及酵母菌数量先下降后上升,乳酸球菌为优势菌种,数量达到106 CFU/g;第2阶段发酵液pH值降至5.0以下,细菌总数、肠道杆菌及酵母菌数量在一个数量级内上下波动,分别为105、104、105,乳酸杆菌成为优势菌种,数量级为106,球菌为105;第3阶段发酵液pH＜4.0,细菌、酵母菌和乳酸菌的数量开始明显减少,肠道杆菌生长基本受到抑制,乳酸杆菌仍是优势菌种,数量级在104。醋酸菌数量一直处于一个非常低的水平。为实现芥菜的自然发酵到人工发酵,可以用乳酸球菌和乳酸杆菌组合当发酵剂,并且适当降低发酵初始pH值。     

Changes in volatile compounds of pickled mustard tuber (Brassica juncea var. tsatsai) during the pickling process

This study was carried out to determine the changes of volatile compounds composition during pickled mustard tuber production. The samples were collected at different pickling stages from the traditional industry production way in Chongqing, China. Gas chromatography–mass spectrometry were performed after simultaneous distillation and extraction. The results showed that ITC (isothiocyanates) possessed the highest relative percentage area (RPA) 78.87%, followed by sulphide compounds with RPA of 14.48%. Main volatile compounds that determined were allyl ITC, dimethyl trisulphide, (2-isothiocyanatoethyl)-benzene, n-Hexadecanoic acid and linolenic acid ethyl ester, which were responsible for the hot and pungent flavour of pickled mustard tuber. The sulphides, acids, aldehydes, alcohols, phenols, esters, nitriles and heterocyclic compounds increase with pickling time but ITC increase at the first and second pickling stage, then start to decrease in the last pickling stage. It was also demonstrated that more than 60-day pickling time was necessary for the formation of the typical aroma notes.     

雪里蕻腌菜风味特的研究（Ⅱ）雪里蕻腌菜挥发性风味成分（续）

由表３可知,雪里蕻腌菜挥发性风味组分主要是一些烃、醇、酮、酯、腈及杂环类化合物,其中二者皆有的醋酸乙酯及乙醇为发酵代谢物,表明雪里蕻腌菜的乳酸发酵,而丁烯腈和异硫氰酸烯丙酯为雪莱中芥子苷的酶解产物。注：表中数值为以苯并噻唑峰面积含量为１.００其它化合物之峰面积与之比值。３．２ 讨论本文采用依据雪里蕻腌菜挥发性组分的酸碱性原理来进行组分离,此较根据化合物极性分离,操作简单易行。因为分离过程一只涉及乙醚一种有机溶剂,所以污染少,特别适合于酸性、碱性组分的分离和嗅感评定。任何化合物必属于酸性、弱酸性、中…     

Influence of sulphate nutrition on flavour components of three cruciferous plants: Radish (Raphanus sativus), cabbage (Brassica oleracea capitata) and white mustard (Sinapis alba)

The effect of sulphate nutrition on the flavour components of three members of the family Cruciferae (radish, cabbage and white mustard) has been investigated. The plants were grown in a glasshouse in sand culture at six concentrations of sulphate in the nutrient medium and their flavour characteristics determined by sensory and gas-chromatographic methods. The latter were based on (a) headspace samples from the raw and cooked vegetables and (b) solvent extracts chromatographed at 200°C. Sensory tests showed that the flavour strengths of the vegetables increased from low values at extreme sulphur deficiency to maxima with increase of the sulphate available to the plant. For radish and mustrad, there was no correlation between total volatile componets (determined by the headspace method) and sulphur content but a highly significant corelation was demonstrated between the latter and less volatile flavour components present in solvent extracts. In the case of mustrad seed. p-hydroxybenzyl isothiocyanate was determined colorimetrically and shown to be correlated with sulphur nutrition. With cabbage, allyl isothiocyanate and total volaile content were determined by a headspace method and each was found to be significantly correlated with sulphate nutrition. It is suggested that the flavour of these plants consists of at least two types of componnts: (a) compounds which impart a bland, generalised “vegetable” flavour to the food and (b) a specific component or components which are perceived as a burning sensation on the tongue sometimes accompanied by a characteristic odour. The former are independent of sulphur nutrition whilst the concentrations of the latter are highly correlated with sulphur nutrition. The effect of sulphate nutrition on growth response, visual deficiency symptoms and mineral composition has been reported.     

Volumetric determination of p-hydroxybenzyl isothiocyanate in sinalbin (p-hydroxybenzylglucosinolate) and in white mustard seed (Sinapis alba L)

p-Hydroxybenzyl isothiocyanate is the constituent responsible for both flavour and aroma in white mustard. This isothiocyanate is not present in the free state as such but is produced as a result of hydrolysis of sinalbin present in the mustard. A survey of the existing methods showed the lack of a specific, quick and a reliable method for the estimation of p-hydroxybenzyl isothiocyanate. A titrimetric method has been developed which is based on the quantitative conversion of p-hydroxybenzyl isothiocyanate into thiocyanate. The thiocyanate is then determined iodometrically after conversion to cyanogen bromide. The method is applicable to pure sinalbin, white mustard and also to mixed mustard flour consisting of black and white mustard.     

Influence of Water Stress on Cold-Induced Sweetening in Leafy Vegetable, Brassica juncea L.

The occurrence of low temperature sweetening in Brussica juncen L., an apparently chilling-tolerant leafy vegetables, has been investigated in relation to the effect of water stress and postharvest age (i.e. fresh harvest vs previously stored samples). The magnitude of cold-induced sweetening in B. juncea leaves was estimated to vary from 10–145% relative to the corresponding nonchilled samples. Previously stored leaves showed greater tendency to accumulate sugars but was apparently less responsive to cold-induced sweetening than freshly harvested leaves. Water stress synergistically enhanced this low temperature sweetening response; markedly greater and/or faster accumulation of sugars occurred in leaves that were both chilled and stressed. The majority of the total sugar increase was attributable to non-reducing sugars.     

Nitrogen nutrition and flavour compounds of carrots (Daucus carota L) cultivated in Mitscherlich pots

Carrots (Daucus carota L) of the cultivar ‘Nanthya’ F₁ were grown in Mitscherlich pots containing quartz sand with inorganic nitrogen fertilisation (five levels, four replications) and time‐controlled drip irrigation. The effect of different nitrogen uptake on the yield and on the amount and composition of essential oils, sugars and organic acids was investigated. Sucrose, glucose and fructose were extracted and analysed by HPLC; L ‐malic acid and citric acid were measured with an enzymatic test. Medium‐ and higher‐boiling flavour components were isolated as essential oils by simultaneous watersteam distillation and pentane extraction (SDE) and separated gas chromatographically (HRGC–FID). Thirteen essential oil components were identified by mass spectrometry as well as by comparison of retention times and quantified by external standards. The higher the supply of nitrogen, the higher was its uptake and as a consequence the higher were the nitrogen and nitrate contents of the leaves as well as the roots of the carrots. Carrots with lower nitrogen application had higher amounts of sucrose and essential oils but lower amounts of glucose and fructose. Fertilisation with nitrogen affected not only the total content but also the composition of the essential oils. A correlation between nitrogen nutrition and organic acids could not be found. © 2000 Society of Chemical Industry     

5个长柄芥品种可食茎和叶的品质对比分析

目的 探究长柄芥蔬菜采后可食部分品质特性,筛选优异品种.方法 对集中种植于成都平原生态条件下的5个长柄芥品种进行采后叶片和叶柄8项品质指标(单株重、株高、维生素C、可溶性蛋白、可溶性糖、叶绿素、纤维素、游离氨基酸)的测试分析.结果 除单株重、株高和叶片可溶性糖含量3项指标外,供试品种间有11个测试指标变异系数大于10％...     

Effect of allyl isothiocyanate on antioxidant enzyme activities,flavonoids and post-harvest fruit quality of blueberries (Vaccinium corymbosum L., cv. Duke)

The effect of allyl isothiocyanate (AITC) on antioxidant enzyme activities, flavonoid content, and fruit quality of blueberries var. Duke (Vaccinium corymbosum L.) was evaluated. Results from this study showed that AITC was effective in maintaining higher amounts of sugars and lower organic acids compared to untreated fruit during storage at 10 °C. However, AITC reduced antioxidant enzyme activities [superoxide dismutase (SOD), guaiacol peroxidase (G-POD), glutathione-peroxidase (GSH-POD), ascorbate peroxidase (AsA-POD), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR)] and non-enzyme components, ascorbate (AsA) and glutathione (GSH). AITC treatments also reduced the amount of phenolic acids (chlorogenic acid, myricetin 3-arabinoside, quercetin 3-galactoside, quercetin 3-arabinoside, and kaempferol 3-glucoside) and anthocyanins (delphinidin 3-galactoside, delphinidon 3-glucoside, delphinidin 3-arabinoside, petunidin 3-galactoside, petunidin 3-glucoside, petunidin 3-arabinoside, malvidin 3-galactoside, and malvidin 3-arabinoside) during storage at 10 °C. The results from this study indicate that AITC does not promote antioxidant property or scavenge constitutive reactive oxygen species (ROS), but maintain blueberry fruit quality through other mechanisms.     

Decomposition of sinigrin by methanol/ammonia/water treatment in model systems and mustard (Brassica nigra L.) seed meal

 Sinigrin (allylglucosinolate) was stored at 20  °C, 40  °C, and 60  °C in solutions containing 10% ammonia in 95% methanol (CH₃OH/NH₃/H₂O). The individual samples were analyzed for their contents of sinigrin, its decomposition product allyl isothiocyanate (AITC) and other reaction products. The major reaction products were allyl thiourea, methyl ester of N-allyl thiocarbamoyl acid and allyl cyanide. A newly identified decomposition product of sinigrin was ethylcyanide. Defatted Brassica nigra seed meal was treated by the CH₃OH/NH₃/H₂O mixture to simulate the procedure used for rape and mustard seed meal detoxification. suspensions of the meal in the above mixture of solvents were heated at 20  °C, 40  °C and 60  °C, respectively. The major reaction products were the same as those arising from sinigrin. Minor products identified were 4-hydroxybenzyl isothiocyanate formed from sinalbin and 2-hydroxy-butenyl cyanide which arises from progoitrin. In all cases, AITC was very rapidly decomposed. Mechanisms explaining sinigrin decomposition are presented and discussed. Received: 3 May 1999     

Glucosinolate content and amino acid composition of rapeseed (Brassica napus) meal as affected by sulphur and nitrogen nutrition

Rapeseed plants have been grown in soil-free culture with varying amounts of nitrogen fertiliser applied as nitrate, and with 50% of the nitrate-N exchanged for ammonium. The experiment was performed at two levels of sulphate fertiliser. Yield, protein content, glucosinolate content and amino acid composition were studied. The glucosinolate content was lower and the protein content was higher at a high level of nitrogen fertiliser. Exchange of 50% of the nitrate-N for ammonium caused no significant change in glucosinolate or protein content. The amount of glucosinolate was higher at the high sulphate level. There were no sulphur-nitrogen interactions. Content of total aspartic acid increased with nitrogen fertilisation, while total content of other amino acids did not change significantly with fertilisation. The effect of a wide variety of applications of sulphate fertiliser on glucosinolate and total amino acid content have been studied in a separate experiment. Although both protein content and methionine content were reduced at a low sulphate level, glucosinolate content was reduced considerably more. Experiments in the field revealed that although a reduction in glucosinolate content of rapeseed may be obtained from using fertilisers low in sulphur on sandy soils this does not seem possible on heavy soils.     

Identifizierung von Glucosinolaten in Rettich (Raphanus sativus L.) und Kreuzungen aus R. sativus L. x Brassica oleracea L. (Raphanobrassica) mittels LC-MS

Identification of glucosinolates in radish (Raphanus sativus L.) and cross-breeds of R. sativus L. x Brassica oleracea L. (Raphanobrassica) by LC-MS. The glucosinolate profiles in Raphanus sativus and new intergenetic as well as interspecific hybrids between Raphanus sativus and Brassica oleracea have been investigated by HPLC-UV and LC-MS. Tentative identification based on UV-spectra and retention times were confirmed by the indivdual LC-MS measurements. In this context three glucosinolates (glucoraphenin, glucoerysolin and 4-methylthiobutenyl glucosinolate), which are known for their nutritional and resistance value in the brassicaceae plants, but are not available as reference standards could be characterized by MS detection for the first time. The presented LC-MS analyses, performed in the API-ES positive mode, proved to be a very sensitive and selective method for the identification of unknown glucosinolates in plant material. Possible applications for breeding research as well as for quality control purposes are discussed.     

The glucosinolate content of the leaf and stem of fodder kale (Brassica oleracea L.), rape (Brassica napus L.) and radicole (Raphanobrassica)

The glucosinolate content of three fodder kales, one fodder rape, one semi-artificial rape and one radicole were determined. The major glucosinolates (mmol kg^?1 dry matter) were: in kale leaf, glucobrassicin (3.21) and sinigrin (3.12); in kale stem, sinigrin (5.82); in rape leaf, gluconapin (3.14) and progoitrin (13.99); in rape stem, gluconapin (3.29) and progoitrin (20.18); in semi-artificial rape leaf, gluconapin (25.64) and progoitrin (9.00); in semi-artificial rape stem, gluconapin (35.33) and progoitrin (12.08); in radicole leaf, progoitrin (4.74) and glucobrassicin (3.28); and in radicole stem, gluconapin (3.26) and progoitrin (5.53). The implications for plant breeding are discussed.     

Influence of sulphate nutrition on the flavour components of garlic (Allium sativum) and wild onion (A. vineale)

Investigation of the relationship between the sulphate nutrition of garlic (Allium sativum) and wild onion(A. vineale) and their flavour strength is now reported. The plants were grown in a glasshouse in sand culture at two concentrations of sulphate in the nutrient medium and their flavour strength determined by sensory, biochemical and gas chromatographic methods. These observations have furnished further examples of environmental control of flavour components. The garlic plants in the two groups differed significantly in their fresh weights per plant. Their sulphur contents also showed that deficiency of this nutrient had been established in spite of the relatively large amount of sulphur introduced in the original cloves. The ratios of total sulphur content in the two groups of plants and of their flavour strengths as determined by total pyruvate values and taste threshold concentrations, respectively, were approximately constant (about 5). Total peak areas in the gas chromatograms increased with increasing (sensory) flavour strength. The garlic plants grown in sand culture were morphologically atypical, possibly because of the high moisture content of the growth medium, but their odour, taste and gas chromatograms were qualitatively indistinguishable from those of field-grown garlic which grew normally. Similar but more pronounced differences of flavour strengths were obtained with A. vineale and in this case the difference in flavour strengths between the deficient and normal plants was about 13-fold. The gas chromatograms of the deficient plants were almost completely lacking in the peaks which are characteristic of Allium sp. The discrepancies between initial and final sulphur contents of the deficient plants are discussed.     

Studies on potassium nutrition of plants IV.—Effect of potassium nutrition on the composition of leaves of cabbage seedlings (Brassica oleracea capitata)

The effect of potassium concentration in the nutrient medium on the composition of leaves of cabbage seedlings has been investigated. The plants were grown in sand culture with seven treatments ranging from extreme deficiency to relatively high potassium concentration. The total amounts of the mineral components were not influenced by the level of potassium nutrition. Similarly, proteins, amino acids and other organic nitrogen components, taken as a whole, did not vary appreciably as shown by the constancy of the Kjeldahl nitrogen values. Sugar (reducing sugars + sucrose) content rose with increasing potassium concentration in the medium to a maximum (11.0%) at 2.5 mequiv./l and fell slightly at the highest K⁺ concentration. Starch content varied in a similar manner but values were, in general, less than half those of the corresponding sugar contents. Total organic acids content was at a maximum (18.6%) when K⁺ concentration in the medium was 0.1 mequiv./l and fell to a minimum (7.7%) at a K⁺ concentration of 2.5 mequiv./l. ‘Other carbohydrates’ (the difference between content of 70% [by vol.] alcohol-insoluble residue and Kjeldahl nitrogen × 6.25) also contributed to the balance of percentage composition; the content rose to a maximum (35.2%) at a K⁺ concentration of 2.5 mequiv./l and fell off both at higher and lower K⁺ concentrations. Within the limits of experimental error, the totals of the leaf components determined were constant over the range of potassium concentrations of 0.1–5.0 mequiv./l in the medium and, on average, 90.7% of the dried leaf was accounted for. Similar differences in mineral composition and ‘protein’, sugars and starch contents were found in plant fractions of different leaf ages in potassium deficiency. The differences were related to differences in potassium content which decreased with increasing leaf age.