Volatile flavour components of garden cress

Using previously reported methods of sample preparation an essence of garden cress was obtained which proved to contain only 11 components. Eight have been identified, all glucosinolate degradation products (isothiocyanates and nitriles), and provide over 95% of the sample. Benzyl derivatives, from glucotropaeolin, are the most abundant. No thiocyanates were obtained.     

Structural,morphological and rheological characterisation of bovine serum albumin–cress seed gum complex coacervate

The interactions between the bovine serum albumin (BSA) and cress seed gum (CSG) were investigated by structural, morphological and rheological characterisation as a function of pH level (7.0–2.0) and biopolymers’ concentrations (BSA, 0.1%, 0.5% and 1%, w/w and CSG, 0.01%, 0.05% and 0.1%, w/w). The results showed that turbidity, zeta potential and coacervate yield values had correlations with the initial number of biopolymers, which are influenced by the level of the positive and negative charges of BSA and CSG. Furthermore, the optimal complexation conditions in terms of pH, CSG-BSA content and yield were 3.5%, 0.05–0.1% and 61.17% respectively. Rheological properties revealed the formation of a weakly gel-like structure with a shear-thinning behaviour. X-ray diffraction (XRD) and scanning electron microscopy (SEM) authenticated an amorphous and branch-like network structure in the coacervate phase respectively. These results reflect that CSG-BSA complex coacervate could be an appropriate biopolymer carrier for susceptible and bioactive compounds.     

软包装水芹菜护绿保脆工艺研究

以水芹为研究对象,以质构、色差、过氧化物酶活性及感官评定为评价指标,研究热烫时间、锌离子浓度及热烫溶液pH对产品品质的影响;以质构和感官评定为指标,考察CaCl2浓度、浸泡时间对水芹品质的影响;以pH、色差及感官评定为指标,考察不同柠檬酸添加量对产品品质的影响.结果表明:水芹最佳护色条件为热烫时间2 min,锌离子浓度200 mg/L,pH 8;最佳保脆务件为0.4％ CaCl2溶液浸泡20 min;柠檬酸最佳添加量为0.15％,在此条件下得到的产品品质最佳.     

The effect of pH,salts and sugars on the rheological properties of cress seed (Lepidium sativum) gum

Effect of shear rate (15–600 s^?1), gum concentration (1–2%), pH (3–9), sucrose (10–40%), lactose (5–15%), NaCl (100–300 mm ) and CaCl₂ (5–50 mm ) was evaluated on apparent viscosity (η_a), flow behaviour index (n), consistency coefficient (K) and yield stress (τ₀) indices of cress seed gum (CSG) solutions. Different rheological models were used to fit the experimental data, although the Herschel–Bulkley model was found the best model. An increase in gum concentration led to an increase in τ₀, η_a, and k and a decrease in n values. The addition of salts lowered the k value; however, the n value showed slight significant change. The presence of sugar resulted in the enhancement of n, k, τ₀ and η_ap values. The existence of yield stress and pseudoplastic behaviour of CSG, its stability against salts, wide range of pH and synergic effect of sugar make it a good thickener and stabiliser in food formulations.     

水芹菜叶蔬菜纸成型工艺研究

围绕水芹菜叶蔬菜纸加工中的成型工艺关键点进行研究.实验发现,使用不粘涂料烤盘作为成型载体,并在70℃的鼓风干燥箱中进行干燥,可以使菜纸得到最佳成型效果.复配胶黏剂效果优于单一胶黏剂.在护色打浆后菜泥中添加0.4％羧甲基纤维素钠(CMC-Na)、0.5％海藻酸钠及2％淀粉组成的复合胶黏剂,并且以1％甘油作为增塑剂,可以获得最佳的纸型和风味.     

Influence of intermittent-direct-electric-current (IDC) on phytochemical compounds in garden cress during growth

The influence of different intensities of applied intermittent-direct-electric-current on the levels of phytochemical compounds in garden cress sprouts was determined. One-week-old treated and non-treated plants were harvested and used to analyse the total phenol content and associated antioxidant activity. The contents of chlorophyll, proteins, in addition to specific elements of macro- and micronutrients, as well as heavy metals, were supplementary determined in order to explain changes in secondary metabolism of the treated garden cress. The results of this study showed that, in contrast to other abiotic elicitors, weak levels of IDC can be applied to promote the biosynthesis of chlorophyll, proteins, and phenolics. An IDC of 1400 mA was effective enough to significantly maximise the total phenol content and other biosynthetic products in garden cress, revealing no signs of damage. The accumulation of heavy metals had no toxic effects in garden cress and did not exceed the legal regulations for human consumption.     

Mycetozoal bloom in a hydroponic culture of garden cress (Lepidium sativum L.)

The role and importance of the true slime moulds (mycetozoans, Mycetozoa, formerly Myxomycetes) for agriculture and food industry are poorly documented, most probably because of a low popularity of these “macroscopic microorganisms” among researchers in the past. Here we report probably for the first time the massive occurrence of true slime moulds in their vegetative, plasmodial form in a product intended for direct consumption, i.e. in a household hydroponic culture of garden cress (Lepidium sativum L.). The plasmodia gradually produced numerous, stalked or sessile sporangia and plasmodiocarps, which made it possible to identify them as Didymium species complex (the stalked sporangia) and Didymium difforme (Pers.) Gray (the sessile sporangia and plasmodiocarps). The mycetozoans were transferred to in vitro culture where they were maintained for several weeks on oat flour. We briefly discuss the importance of this observation from the point of view of biochemical interactions between the plant and the true slime moulds in a general context of slime mould biology. Our observation indicates that the presence of mycetozoan material in food products may be frequent, while its influence on food safety and quality remains unknown.     

Influence of sulfur and nitrogen supply on growth,nutrient status and concentration of benzyl‐isothiocyanate in cress (Lepidium sativum L.)

BACKGROUND: The supply of nitrogen (N) and sulfur (S) exerts an interactive effect on glucosinolate (GS) accumulation in Brassica vegetables, but the consequences for the concentration of isothiocyanates (ITCs), released after decomposition of GS by myrosinase, have rarely been investigated. In addition to their phytosanitary function GS have also been discussed as transient S reservoir. RESULTS: Cress (Lepidium sativum, L.) plants were cultivated with varied supply of N (0.5, 1.0 and 2.0 g pot^?1) and S (0, 0.05 and 0.2 g pot^?1). Concentrations of total N and S and hence the N/S ratio responded significantly, as did the concentrations of nitrate and sulfate. Concentrations of benzyl‐ITC, derived from glucotropaeolin (benzyl‐GS), ranged from 6.7 to almost 30 µmol (g dry matter)^?1 and were negatively affected by high N supply. For a given S supply the benzyl‐ITC concentration was inversely related to the N/S ratio, an indicator of the S nutritional status. CONCLUSION: The results do not support the view that GS act as a transient S reservoir. Rather, moderate N and adequate S supplies lead to increased concentrations of this pharmacologically important constituent of cress. Copyright © 2008 Society of Chemical Industry     

磷脂含量对煎炸油烟点、耐寒性、氧化稳定性 和煎炸稳定性的影响

通过添加大豆卵磷脂,使大豆油、菜籽油和棕榈油中磷脂含量分别为本底值、10、20、30、40、50 mg/kg,测定不同磷脂含量的3种煎炸油的烟点、耐寒性、氧化诱导时间,同时检测3种煎炸油在170℃下煎炸不同食材过程中的感官品质、酸价、过氧化值和极性组分含量的变化,以评价其煎炸稳定性。结果表明:随着磷脂含量的增加,大豆油、菜籽油、棕榈油烟点呈下降趋势,其中棕榈油烟点下降受磷脂影响最大;耐寒性随着磷脂含量增加整体呈下降趋势;氧化诱导时间随磷脂含量的增加呈波动变化趋势;在本试验范围内,磷脂含量对煎炸油煎炸稳定性影响的规律尚不明显。     

Natural pigments: carotenoids, anthocyanins, and betalains--characteristics, biosynthesis, processing, and stability

Pigments are present in all living matter and provide attractive colors and play basic roles in the development of organisms. Human beings, like most animals, come in contact with their surroundings through color, and things can or cannot be acceptable based on their color characteristics. This review presents the basic information about pigments focusing attention on the natural ones; it emphasizes the principal plant pigments: carotenoids, anthocyanins, and betalains. Special considerations are given to their salient characteristics; to their biosynthesis, taking into account the biochemical and molecular biology information generated in their elucidation; and to the processing and stability properties of these compounds as food colorants.     

Garden cress oil as a vegan source of PUFA: Achieving through optimized supercritical carbon dioxide extraction

With more people shifting to healthier and environment-friendly lifestyles, the vegan diet has recently gained popularity. Nevertheless, this kind of diet comes with its own limitations in terms of adequate availability of nutrients, for example, essential fatty acids. The primary source for these includes fish and other marine animals, hence not accepted by the vegan population. The plant source is limited. The present work focuses on exploring garden cress (GC) seed oil - an easily available seed, with considerable polyunsaturated fatty acids (PUFA). Conventionally, Soxhlet extraction of vegetable oils is done using solvents like hexane. However, selective extraction of PUFA, phytosterols, and tocopherols could be done by supercritical-CO₂ (SC-CO₂) extraction of oil from the GC seeds with proper optimization of extraction parameters. The PUFA content was found to be 38% in the case of oil extracted with n-hexane. This was enriched to nearly 50% PUFA, when extracted at 350 bar pressure, 60 °C temperature, and 30 g/min flow rate in case of SC-CO₂ extraction. At similar conditions, even tocopherol contents were improved significantly from 486 to 1138 ppm. Further, oil enriched with unsaponifiable matter (2.3%) containing major phytosterols like campesterol, stigmasterol, β-sitosterol, and isofucosterol was obtained at 20 g/min flow rate itself. Another major advantage of SC-CO₂ extraction is the selective extraction of oil from the seed, leaving behind the phospholipids. This in turn eliminates one step of refining, thereby making the process economically viable. The use of co-solvents resulted in nutritionally enriched GC seed oil at a pressure of 250 bar. It is quite evident from the findings of this study that, careful selection of process parameters of SC-CO₂ extraction of GC seed oil can result in a nutritionally enriched vegan source of PUFA, using an emerging cleaner and greener technology.Industrial relevanceThere is a huge demand for newer vegan sources of PUFA. GC seed oil can be one of them. This investigation aimed at process development for extracting PUFA and tocopherol, phytosterol enriched GC oil using eco-friendly SC-CO₂ extraction. SC-CO₂ extraction is becoming more popular and the economic feasibility is proven for the higher scale of operation. As this oil can be encapsulated and sold at a reasonably good price, this work has significant industrial relevance.     

文冠果壳总黄酮分离纯化及稳定性研究

以吸附率和解吸率为评价指标,对大孔树脂分离纯化文冠果壳总黄酮的工艺进行优化,并研究纯化后文冠果壳总黄酮的稳定性。结果表明,文冠果壳总黄酮的最佳分离纯化工艺为:采用XAD-1600树脂,上样液pH=4,上样浓度0.5mg/mL,吸附时间6h,上样流速2BV/h,洗脱液流速3BV/h,洗脱液乙醇浓度40%。该条件下,纯化后总黄酮的纯度为(70.15±1.03)%,回收率为(89.63±1.58)%。稳定性试验表明:文冠果壳总黄酮在低温、酸性、避光条件下性质稳定。     

蛋白质、多糖和多酚混合体系稳定性研究

该文研究蛋白质、多糖和多酚混合体系的稳定性,在单因素实验基础上,采用Box–Behnken中心组合设计的方法,研究各自变量及其交互作用对蛋白质,多糖和多酚混合体系稳定性的影响。确定其最佳条件:温度为37.75℃,p H为5.25,离子浓度为0.15 mol/L,在此条件下,稳定性最好。