Nutritive value of rapeseed meal: Effects of individual glucosinolates

In the first of a series of studies on the nutritional value of rapeseed meal, rats were fed diets containing six individual glucosinolates over a period of 29 days. The diets included progoitrin and gluconapin both of which are major components of high glucosinolate rapeseed cultivars. No reduction of feed intake or growth rate was noted and thyroid weights were significantly affected only by the progoitrin diet, which also produced small increases in the weights of the livers and kidneys. There was no depression of plasma thyroid hormone levels.     

The Physiological Importance of Glucosinolates on Plant Response to Abiotic Stress in Brassica

Glucosinolates, a class of secondary metabolites, mainly found in Brassicaceae, are affected by the changing environment. This review is focusing on the physiological significance of glucosinolates and their hydrolysis products in the plant response to different abiotic stresses. Special attention is paid to the crosstalk between some of the physiological processes involved in stress response and glucosinolate metabolism, with the resulting connection between both pathways in which signaling mechanisms glucosinolate may act as signals themselves. The function of glucosinolates, further than in defense switching, is discussed in terms of alleviating pathogen attack under abiotic stress. The fact that the exogenous addition of glucosinolate hydrolysis products may alleviate certain stress conditions through its effect on specific proteins is described in light of the recent reports, but the molecular mechanisms involved in this response merit further research. Finally, the transient allocation and re-distribution of glucosinolates as a response to environmental changes is summarized.     

Pilot-scale two-phase extraction of canola

An extraction process was developed in our laboratory for rapeseed (canola) with 10% (w/w) ammonia in methanol, containing 5% (vol/vol) water, and hexane to simultaneously produce an improved meal and a high-quality oil. To remove the hazards associated with the use of ammonia, a two-phase solvent extraction, with 0.08% (w/w) sodium hydroxide replacing the ammonia, was tested on a semipilot scale with a Szego mill and a Karr reciprocating-plate extraction column. Flooding curves and appropriate agitation parameters were examined for this system. Then, the effects of polar solvent-to-seed ratio, slurry-to-hexane flow ratio, plate amplitude and plate agitation frequency on extraction efficiency were investigated. The process is technically viable for industrial application. A meal that contained 0.9% residual oil, 44.4% protein and 2.79 mmol/kg glucosinolates (moisture and oil-free basis) and a miscella with 19.5% oil were obtained.     

Glucosinolates in etiolated sprouts of sea-kale (Crambe maritima L)

Sea-kale, a long-forgotten vegetable, could make a resurgence due to its culinary attractiveness. Unfortunately, as with most cruciferous plants, its quality may be reduced owing to the presence of glucosinolates, mainly known for their antinutritional properties. The aim of this study was to evaluate the actual amount of these compounds found in edible sea-kale sprouts, using qualitative and quantitative analysis by liquid chromatography carried out after treatment by freezing, blanching and cooking. Before treatment, the quantity of glucosinolates, of which more than 80% is represented by epi-progoitrin, was found between 5.4 and 7.3 μmol g^?1 of fresh matter. In this study, freezing then thawing causes a nearly complete decomposition of glucosinolates into nonidentified compounds which are most probably 5-vinyloxazolidine-2-thionc and nitrites. Cooking for 4 min (blanching) brings about through leaching, a nearly 30% reduction. A greater decrease (76%) can be obtained with a cooking time of 20 min. The amount of glucosinolates found in sea-kale was compared with that of other commonly used cruciferous vegetables and there appears to be practically no risk when consumed on a monthly basis. At present sea-kale remains a desired vegetable in gastronomical dishes.     

Oviposition stimulants inBarbarea vulgaris forPieris rapae andP. napi oleracea: isolation,identification and differential activity

The closely related butterflies,Pieris rapae andP. napi oleracea, readily laid eggs onBarbarea vulgaris in greenhouse cages. When offered a choice between cabbage andB. vulgaris, P. rapae showed no preference, butP. napi oleracea preferredB. vulgaris. Bioassays of extracts ofB. vulgaris foliage revealed the presence of oviposition deterrent(s) in l-butanol extracts as well as stimulants in the postbutanol water extracts. However, the deterrent effect was apparently outweighed by the strong stimulatory effect in the whole plants. The postbutanol water extract was preferred over an equivalent cabbage extract by both species, but more significantly in the case ofP. napi oleracea. The stimulants were isolated by open column chromatography and HPLC, and the activity was associated with three glucosinolates.P. napi oleracea was more sensitive thanP. rapae to the natural concentration of compounds1 and3, whereas both species were strongly stimulated to oviposit by natural concentrations of compound2. Compounds1 and2 were identified as (2R)-glucobarbarin and (2S)-glucobarbarin, respectively, and3 was identified as glucobrassicin, on the basis of their UV, mass, and NMR spectra. When the pure compounds were tested at the same concentrations applied to bean plants, the (2R)-glucobarbarin at 0.2 mg/plant was preferred over a standard cabbage extract by both butterfly species. However, at a dose of 0.02 mg/plant,P. rapae preferred the cabbage extract whereasP. napi oleracea still preferred the (2R)-glucobarbarin. No such difference in response of the two species to the same two concentrations of (2S)-glucobarbarin was obtained. The results indicate a distinct difference in sensitivity of these butterflies to the epimers of glucobarbarin, and the differences in behavioral responses of the two butterfly species depend to a large extent on the concentration of stimulant present.     

Exploring new potential health‐promoting vegetables: glucosinolates and sensory attributes of rocket salads and related Diplotaxis and Eruca species

BACKGROUND: Rocket salads (Diplotaxis tenuifolia and Eruca vesicaria) are presently highly appreciated salad vegetables. Related species are consumed as food plants in several regions, and may contribute to differentiation in the fresh food supply chain. Glucosinolates are well‐known healthy phytochemicals and responsible for positive and negative sensory properties of edible Brassicaceae. To investigate the potential for exploitation of new crops, Diplotaxis and Eruca germplasm was subject to sensory evaluation and glucosinolate analysis. RESULTS: Typical rocket salad flavour and pungency were perceived as positive sensory traits. Bitter, and especially herbaceous notes, characterised the groups of less accepted accessions. The groups classified as significantly unpleasant were characterised by high glucosinolate content, with either sinigrin (strong perceived pungency, flavour and several other additional sensory notes), or sinalbin/gluconapin (strong herbaceous note, low flavour perceived), as the dominant components. CONCLUSIONS: Low glucosinolate content, and a composition rich in recognised health‐promoting components (glucoerucin, glucoraphanin) were associated with higher acceptance. In relation to food uses, moderate glucosinolate content and high acceptance may be a better option to enhance the intake of healthy phytochemicals than high glucosinolates and potential rejection. High glucosinolate types may find better perspectives in the field of food integrators. Copyright © 2009 Society of Chemical Industry     

Effects of α-, β- and maltosyl-β-cyclodextrins use on the glucoraphanin–sulforaphane system of broccoli juice

Cyclodextrins (CDs) are macromolecules with several industrial applications, being particularly used in the food industry as health-promoting compounds protection agents, as flavour stabilizers, or to eliminate undesired tastes and browning reactions, among others. This study shows the effects of α- (10, 30 and 40 mmol L⁻¹), β- (3, 6 and 10 mmol L⁻¹) and maltosyl-β-CDs (30, 60 and 90 mmol L⁻¹) use on the health-promoting glucoraphanin–sulforaphane system of a broccoli juice up to 24 h at 22 °C. Maltosyl-β-CD (90 mmol L⁻¹) highly retained glucoraphanin content after 24 h at 22 °C, showing better effectiveness than β-CD (10 mmol L⁻¹). Sulforaphane was efficiently encapsulated with β-CD at just 3 mmol L⁻¹, and the sulforaphane formed was stable during 3 h at 22 °C. On the other hand, 40 mmol L⁻¹ α-CD retained a high glucoraphanin content in broccoli juice. In contrast, glucoraphanin levels in juice without CDs decreased by 71% after 24 h. Consequently, CDs addition may potentially preserve glucoraphanin in this broccoli juice during industrial processing with the possibility to be later transformed by endogenous myrosinase after ingestion to the health-promoting sulforaphane. © 2018 Society of Chemical Industry     

Food systems approach to cancer prevention

New cancer cases are expected to surge 57% worldwide in the next two decades. The greatest burden will be in low- and middle-income countries that are ill equipped to face this epidemic. Similarly, in the United States, low-income populations are at greater risk for cancer. As most cancers contain over 50 genetic alterations, and as these alterations define dysregulation of over 10 different critical cellular signaling pathways, a “silver bullet” treatment is not effective against most cancers. Instead, the latest World Cancer Report (2012) suggests a research shift toward developing prevention strategies for cancer. Accumulating evidence suggests that a diet high in plant-based foods is preventive of a variety of chronic diseases, including cancer. A plethora of bioactive compounds—such as polyphenols, glucosinolates and carotenoids in fruits, vegetables, grains, and legumes—are shown to suppress a variety of biological capabilities required for tumor growth. While much research has shown that plant bioactive compounds can suppress sustained proliferative signaling, angiogenesis, and metastasis, as well as promote cancer stem cell apoptosis, public health campaigns to increase fruit and vegetable consumption have, overall, been less effective than desired. Thus, there is a need for innovative strategies to support increased consumption of bioactive compounds for cancer prevention particularly in vulnerable populations. Many practices of the farm-to-fork continuum, including preharvest practices, postharvest storage, and processing and consumer practices, affect a food's bioactive compound content, composition, and chemopreventive bioactivity. Food system practices may be adjusted to reduce the toxic compound levels (e.g., glycoalkaloids in potatoes) and improve the bioactive compound profile, thus, elevate the cancer fighting properties of fruits, vegetables, and other food products. This review presents current scientific evidence outlining farm-to-fork effects on fruit and vegetable bioactive compounds in order to aid the development of new and reasonable strategies for cancer prevention.