Effect of storage temperature and duration on glucosinolate,total vitamin C and nitrate contents in rocket salad (Eruca sativa Mill.)

The effect of storage temperature and duration on nitrate, total vitamin C and glucosinolate (GSL) contents was investigated in rocket salad (Eruca sativa Mill.) grown in soilless culture. Harvested plants were either maintained intact as leaves with roots (RL) or separated as leaves only (LO) before being placed in oriented polypropylene packages and immediately stored at 4 °C (RL and LO) or 15 °C (LO only) in darkness. Packages were sampled after 1, 3, 6 and 10 days of storage (DOS) and, along with fresh samples (0 DOS), submitted to chemical analysis. For RL (4 °C), leaf moisture content decreased gradually with increasing storage duration, from 98.7% at 1 DOS to 93.8% at 10 DOS. For LO (15 °C), leaf colour at 10 DOS had shifted from an initial greenish hue to a yellowish one. Nitrate contents were highest at 10 DOS in all treatments but did not show any significant differences between LO (15 °C) and RL (4 °C). Total vitamin C content ranged from 0.87 to 1.81 mg g^?1 fresh weight and was higher in both LO (4 °C) and RL (4 °C) leaves than in those of LO (15 °C) regardless of storage duration. Total GSL content in the leaves of both LO (4 °C) and LO (15 °C) increased up to 3 DOS and decreased thereafter. The correlation between total vitamin C and GSL contents only existed at 0 DOS before storage and at 3 DOS of LO (15 °C) during storage in all treatments. Storage temperature generally had a significant effect on GSLs individually or collectively, except for 4‐methoxyglucobrassicin. Copyright © 2007 Society of Chemical Industry     

高效液相色谱-串联质谱法测定芝麻菜中萝卜硫素

目的 建立高效液相色谱-串联质谱法测定芝麻菜中萝卜硫素的分析方法 。方法 芝麻菜样品加入一定量pH 6磷酸缓冲溶液,于50℃水浴下振荡水解2 h,冷却至室温后经二氯甲烷萃取,萃取液吹干后用乙腈复溶,以0.1%甲酸水溶液-乙腈为流动相进行梯度洗脱,经Zorbax SB C18色谱柱(100 mm×2.1 mm, 3.5μm)进行分离,采用电喷雾正离子多反应监测(multiple response monitoring, MRM)模式检测,外标法定量测定新鲜芝麻菜中萝卜硫素的含量。结果 萝卜硫素在10～500ng/m L质量浓度范围内线性关系良好(r2≥0.999),检出限为4.0μg/kg,定量限为13.0μg/kg,在低、中、高3水平的加标回收率为95.7%～104.0%,相对标准偏差低于1.000%。应用本研究建立的方法 对不同生长周期新鲜芝麻菜中萝卜硫素含量检测,变化趋势与文献报道结果 一致,萝卜硫素在生长过程中逐渐积累,成熟前期达到最高,到成熟后期由于植物衰老萝卜硫素含量存在下降趋势。结论 本方法 满足准确度、精密度及灵敏度等要求,适用于新鲜芝麻菜中萝卜硫素的检测。     

Characterization and prediction by near-infrared reflectance of mineral composition of rocket (Eruca vesicaria subsp. sativa and Eruca vesicaria subsp. vesicaria)

BACKGROUND: Minerals are essential for human nutrition and must be obtained from our diet. Crucifer vegetables are a good source of these nutrients. Our objectives were to determine the genetic variability for mineral content and to evaluate the use of near‐infrared reflectance spectroscopy (NIRS) for prediction of ashes and minerals among and within the rocket species Eruca vesicaria subsp. sativa and vesicaria. The minerals studied were iron (Fe), copper (Cu), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), manganese (Mn) and zinc (Zn). RESULTS: The maximum mean values obtained for all the accessions (mean ± SE) were 235.5 ± 1.5 mg ashes kg^?1, 273.3 ± 4.2 mg Fe kg^?1, 18.1 ± 0.4 mg Cu kg^?1, 2.8 ± 0.1 g Na kg^?1, 71.6 ± 1.0 g K kg^?1, 64.6 ± 1.2 g Ca kg^?1, 6.8 ± 0.1 g mg kg^?1, 101.6 ± 1.2 mg Mn kg^?1, and 67.1 ± 0.4 mg Zn kg^?1 of dry weight. CONCLUSION: The statistical analysis showed significant differences for all the minerals, except Ca, for each accession studied individually and for accessions grouped within countries. The results indicate that NIRS can be used as a rapid screening method for determining total mineral, Fe, Na, K, and Zn in rocket. Copyright © 2011 Society of Chemical Industry     

高效液相色谱-串联质谱法检测新鲜芝麻菜中芝麻菜苷

目的 建立高效液相色谱-串联质谱法(High-performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS)测定芝麻菜中芝麻菜苷的分析方法。方法 芝麻菜样品采用80%(v/v)甲醇-水在70 ℃水浴下提取20 min,以0.1%甲酸水溶液-乙腈为流动相进行梯度洗脱,经C₁₈ 色谱柱进行分离,采用电喷雾负离子多反应离子检测模式对芝麻菜苷进行检测,外标法定量。结果 芝麻菜苷在10-500 ng/mL浓度范围内线性良好,相关系数大于0.995,检出限为3.0 μg/kg,定量限为10.0 μg/kg,平均回收率为96.7%,相对标准偏差为3.86%。结论 该方法灵敏度高、回收率好、重复性强,可快速准确对芝麻菜中芝麻菜苷进行测定。     

Evaluating Extraction Conditions of Glucosinolate Hydrolytic Products from Seeds of Eruca sativa (Mill.) Thell. Using GC‐MS

Glucosinolates and their hydrolytic products form an important class of plant secondary metabolites involved in various plant defense‐linked mechanisms. The successful isolation of particular glucosinolate hydrolytic products is limited by a number of factors like understanding the parent glucosinolate moiety, solubility, and stability under different drying conditions. The extraction protocols currently available were modified to achieve both an increased yield as well as an increased number of hydrolytic products. Eruca sativa (Mill.) Thell. (called arugula in the U.S.A.), a rich source of varied glucosinolates, was used for the standardization of different extraction protocols. We exploited the volatile nature of the glucosinolates and developed a method that not only enhanced the yield of glucosinolate hydrolytic products, but also reduced undesired compounds. Among all the tested protocols, hydrodistillation using Clevenger apparatus was judged as the best protocol, which was evident from an enhanced yield as well as an increased number of hydrolytic products when compared to the other methods as monitored by gas chromatography‐mass spectrometry.     

Comparative evaluation of atmospheric and vacuum microwave‐assisted extraction of bioactive compounds from fresh and dried Centella asiatica L. leaves

Microwave‐assisted extraction (MAE) involves extraction under higher‐temperature and oxygen‐rich environment, which may cause degradation of bioactive compounds being extracted. Reducing the extraction temperature by reducing the system pressure is thus of interest. Nevertheless, information is lacking on the kinetics of vacuum microwave‐assisted extraction (VMAE) at various pressures. Detailed temperature evolution of a material–solvent mixture during VMAE is also not available. This study investigated the extraction kinetics of triterpene saponins and phenolics from both fresh and dried Centella leaves during MAE and VMAE at various pressures. In the case of fresh leaves, the maximum contents of triterpene saponins were reached when VMAE was performed at 60 kPa, whereas the maximum total phenolics content (TPC) was achieved when the extraction was performed at atmospheric condition. In the case of dried leaves, the maximum triterpene saponins contents as well as TPC were achieved when extraction was performed at atmospheric condition.     

Rocket salad (Diplotaxis and Eruca spp.) sensory analysis and relation with glucosinolate and phenolic content

BACKGROUND: Salad crops of the Brassicaceae family, such as Diplotaxis tenuifolia and Eruca vesicaria, commonly referred to as ‘rocket salads’, have attracted considerable interest as culinary vegetables because of their strong flavour and their content of putative health‐promoting compounds. Among such compounds, glucosinolates and phenolics are well‐known phytochemicals with an important role also in determining the characteristic flavour of these species. In this study, to identify potentially high‐value rocket salads, 37 cultivated types were examined for sensory characters and their relations with glucosinolate and phenolic contents, which ranged from 0.76 to 3.03 g kg^?1 dry weight (DW) and from 4.68 to 31.39 g kg^?1 DW, respectively. RESULTS: The perception of bitter taste was significantly affected by specific glucosinolates, namely progoitrin/epiprogoitrin and dimeric glucosativin. Aroma intensity was negatively related to glucoalyssin content, whereas pungency was significantly related to total glucosinolate content. Kaempferol‐3‐(2‐sinapoyl‐glucoside)‐4′‐glucoside was positively and significantly related to all flavour trait perceptions. Aroma intensity, pungency, crunchiness and juiciness were positively related to typical rocket salad flavour perception through a prominent direct effect. CONCLUSION: Aroma intensity, pungency, crunchiness and juiciness were strong determinants of overall rocket salad flavour perception. Visual traits also characterised sensory components. Bitterness, usually considered a negative flavour trait, was moderately perceived in the examined material, without negatively affecting typical flavour perception. In the range of the examined material, glucosinolate content did not contrast with typical flavour, demonstrating that good taste and putative health‐promoting properties may coexist. Copyright © 2011 Society of Chemical Industry     

Blanching and long‐term freezing affect various bioactive compounds of vegetables in different ways

An extensive study on the effects of blanching/freezing and long‐term freezer storage on various bioactive compounds of more than 20 commonly used vegetables was performed. Effects were strongly plant species‐dependent. Contents of dietary fibre components either were not affected or increased slightly. Minerals in general were also stable, but some losses of soluble minerals by leaching were observed. Phenolic antioxidants and vitamins were clearly more sensitive. Significant losses (20–30%) of antioxidant activity and total phenolics were detected in many vegetables. A qualitative HPLC profiling method for phenolic antioxidants was developed which proved to be very useful when evaluating the complex behaviour of phenolics during food processing. Up to one‐third of vitamin C contents were lost during blanching, and further slight losses were detected during storage. Folic acid turned out to be very sensitive to blanching, with more than half of the vitamin being lost, but was stable during freezer storage. Carotenoids and sterols were not affected by blanching or freezer storage. The usefulness of the applied screening methods for evaluation of the effects of processing on vegetables is shown. Copyright © 2003 Society of Chemical Industry     

Changes of bioactive compounds and anti‐oxidant activity during cold storage of carrots

Carotenoids, total phenolics and anti‐oxidant activity of carrots were determined during 6 months of storage at 0 °C, 85–90% relative humidity. In addition to changes in CIE colour parameters (L*, a*, b*, h and C), physicochemical properties of carrots including water soluble solids; pH and titratable acidity were evaluated. Cold storage of carrots did not affect the carotenoid levels (β‐carotene, α‐carotene and total carotenoid) except lutein, which showed a 37.5% loss. Total phenolic concentration of carrots decreased significantly (P < 0.05) over the entire storage period. The anti‐oxidant activity of carrots decreased with a level of 31% and was found correlated with total phenolics and lutein content in carrots. While CIE L* and a* parameters decreased significantly (P < 0.05) after 6 months of storage, the b* and C parameters were statistically unchanged for the first 4 months of storage, but decreased gradually for the following period.     

Designing novel industrial and functional foods using the bioactive compounds from Nigella sativa L. (black cumin): Biochemical and biological prospects toward health implications

Nigella sativa is one of the nutraceuticals that has gained popularity and studied extensively in recent decades as it is considered a safe medicinal plant for use as a dietary supplement. N. sativa contains a wide variety of bioactive substances, which include polyphenols, volatile oils (thymoquinone and p-cymene), proteins, and peptides. The biological attributes of N. sativa include antioxidant, antimicrobial, antifungal, anti-inflammatory, anticancer, antidiabetic, antihypertensive, hypolipidemic, and antioxidant activities, which have potential applications for the prevention of a variety of chronic diseases. In the food industry, N. sativa improves the sensory qualities, shelf life, strength, and freshness of foods, such as bread, pizza, biscuits, cookies, and cakes. This review discusses the industrial use of N. sativa, which includes processing technologies to enhance its health-promoting properties as well as the isolation of nutraceutical components.     

Commercial quality, major bioactive compound content and antioxidant capacity of 12 cultivars of loquat (Eriobotrya japonica Lindl.) fruits

BACKGROUND: Modern consumers are increasingly interested in their personal health and expect the food they purchase to be tasty and attractive while being safe and healthful. The aim of this study was to determine the commercial quality, characterise the antioxidant capacity and quantify the major bioactive compounds of 12 cultivars of loquat fruits in order to establish a database for utilising these germplasm resources. RESULTS: Of the 12 cultivars, ‘Guanyu’ produced the biggest fruits, while ‘Tianzhong’ and ‘Bingtangzhong’ had the highest soluble solids content but the lowest titratable acidity. ‘Taipinghong’ was reddest in colour. Sucrose, fructose, glucose and sorbitol were the major sugars in loquat fruits, with the highest total sugar content being observed in ‘Bingtangzhong’ and ‘Tianzhong’. Phenolics and flavonoids were the main bioactive compounds and were abundant in ‘Tianzhong’ and ‘Zhaozhong’. ‘Taipinghong’ had the highest total carotenoid content, while ‘Qingzhong’ had the highest vitamin C content. ‘Tianzhong’, ‘Bingtangzhong’ and ‘Ninghaibai’ showed higher antioxidant activity than the other cultivars, as measured by assays of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2‐azino‐bis(3‐ethylbenzthiozoline‐6‐sulfonic acid) (ABTS) scavenging and ferric‐reducing/antioxidant power (FRAP). CONCLUSION: Commercial fruit quality, major bioactive compound content and antioxidant capacity varied greatly among the 12 cultivars. ‘Bingtangzhong’ and ‘Tianzhong’ were the highest‐ranking cultivars based on their good commercial quality and high nutritional value. The loquat fruits with higher total phenolic and flavonoid contents also had clearly higher antioxidant capacities. Copyright © 2011 Society of Chemical Industry