Conversion of Canola Meal into a High-Protein Feed Additive via Solid-State Fungal Incubation Process

The study goal was to determine the optimal fungal culture to reduce glucosinolates (GLS), fiber, and residual sugars while increasing the protein content and nutritional value of canola meal. Solid‐state incubation conditions were used to enhance filamentous growth of the fungi. Flask trials were performed using 50 % moisture content hexane‐extracted (HE) or cold‐pressed (CP) canola meal with incubation for 168 h at 30 °C. Incubation on HE canola meal Trichoderma reesei (NRRL‐3653) achieved the greatest increase in protein content (23 %), while having the lowest residual levels of sugar (8 % w/w) and GLS (0.4 μM/g). Incubation on CP canola meal Trichoderma reesei (NRRL‐3653), A. pullulans (NRRL‐58522), and A. pullulans (NRRL‐Y‐2311‐1) resulted in the greatest improvement in protein content (22.9, 16.9 and 15.4 %, respectively), while reducing total GLS content from 60.6 to 1.0, 3.2 and 10.7 μM/g, respectively. HE and CP canola meal GLS levels were reduced to 65.5 and 50.7 % by thermal treatments while solid‐state microbial conversion further reduced GLS up to 99 and 98 %, respectively. Fiber levels increased due to the concentration effect of removing oligosaccharides and GLS.     

Effect of thermal treatment on glucosinolates and antioxidant-related parameters in red cabbage (Brassica oleracea L. ssp. capitata f. rubra)

The effects of various thermal processing treatments (blanching, boiling and steaming) of red cabbage, Brassica oleracea L. ssp. capitata f. rubra cv. ‘Autoro’, were assessed for the levels of glucosinolates (GLS), total phenols (TP), total monomeric anthocyanins (TMA), l-ascorbic acid (L-AA) and soluble sugars, as well as for the antioxidant potential by the ferric reducing ability power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. Individual native GLS were determined by ion-pair HPLC-MS/DAD. There were significant (p < 0.05) losses in blanched red cabbage: TP, 43%, TMA 59%, FRAP 42%, ORAC 51%, L-AA 48% and soluble sugars 45%. Boiling gave less extensive reductions: TP 16%, TMA 41%, FRAP 17%, ORAC 19%, L-AA 24% and soluble sugars 19%. Steaming caused no losses for TP, ORAC, FRAP or soluble sugars. However, significant reductions were found for TMA and L-AA, with 29% and 11%, respectively. In general losses were accounted for in the processing waters; however, TMA was not fully recovered, indicating degradation. Total GLS were severely affected by processing, with reductions of 64%, 38% and 19% in blanched, boiled and steamed red cabbage, respectively. Total aliphatic and indole GLS were similarly affected. Lost GLS were partially recovered in the processing water.     

Effects of some technological processes on glucosinolate contents in cruciferous vegetables

Effects of blanching, boiling and freezing of selected cruciferous vegetables (Brussels sprouts, white and green cauliflower, broccoli, and curly cale) on their glucosinolate (GLS) contents were determined. It was found that blanching and cooking of the vegetables led to considerable (P < 0.05) losses of total GLS, from 2.7 to 30.0% and from 35.3 to 72.4%, respectively. No systematic changes in total GLS were found in the vegetables that were blanched and frozen for 48 h. In addition, the highest concentration of cancer-protective compounds, such as aliphatic and indole GLS, were found in Brussels sprouts (sinigrin and glucobrassicin) and in broccoli (glucoraphanin).     

Partial characterization of white cabbages (Brassica oleracea var. capitata f. alba) from different regions by glucosinolates, bioactive compounds, total antioxidant activities and proteins

Glucosinolates (GLS), antioxidative compounds, total radical scavenging activities (TRSAs) and proteins of white cabbage samples derived from different regions of Europe, collected in the spring and autumn, were studied. Glucobrassicin and sinigrin were the dominating GLS in all analyzed cabbage samples. Depending on origin, these two GLS accounted for ∼30% to ∼70% of the total. The total GLS content ranged from 3.3 to 7.7 μmol/g dw in lyophilized vegetables. Assays based on electron transfer [total phenols by Folin-Ciocalteu reagent (FCR), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] radical cation (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH)] were used to compare the TRSAs and the main bioactive compounds in cabbage. Total polyphenols varied from 2.4 to 4.9 GAE/g dw. The TRSAs ranged from 2.7 to 8.2 μmol TE/g dw in ABTS test and from 2.4 to 5.4 μmol TE/g dw in DPPH assay. The maximum amount of polyphenol compounds, antioxidant activity, as well as total GLS content, were recorded in Belgian cabbage harvested in the autumn and the lowest ones were found for Poland 2 cabbage harvested in the spring. In extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) proteins from cabbage leaves only in samples from England and Belgium some differences in patterns were found in the regions of 60 and 97 kDa. The calculated correlations between antioxidative potency and the abundance of bioactive compounds were highly statistically significant. This suggests that TRSA could serve as a means of standardization of natural mixtures, at least in the case of cabbage, necessary to compare results of biological studies carried out for vegetable derived samples.     

Total isothiocyanate yield from raw cruciferous vegetables commonly consumed in the United States

Dietary isothiocyanates are a group of promising chemopreventive agents obtained primarily from cruciferous vegetables. Due to their potent chemopreventive and/or anti-cancer activities, there is a growing interest in assessing dietary isothiocyanate exposure and its impact on human health. Using the HPLC-based cyclocondensation assay, the current study measured total isothiocyanate yield from raw cruciferous vegetables. A total of 73 samples comprising nine types of cruciferous vegetables were analyzed. We observed a wide range of isothiocyanate content across the individual vegetables with an average level of 16.2 μmol/100 g wet weight, ranging from 1.5 μmol in raw cauliflower to 61.3 μmol in raw mustard greens. The data represent the maximum amount of isothiocyanates released from the intake of raw cruciferous vegetables. Given that the vegetables assayed in this study include the most commonly consumed cruciferous vegetables in western diets, the data may be particularly useful in estimation of dietary isothiocyanate exposure in these populations. However, due to the variation observed within each vegetable, biomarkers such as urinary isothiocyanate level may be necessary for accurate estimation of individual exposure.     

Time dependence of bioactive compounds and antioxidant capacity during germination of different cultivars of broccoli and radish seeds

Optimisation of the germination process of different cultivars of broccoli (Brassica oleracea var. italica cv. Lucky, cv. Tiburon and cv. Belstar) and radish (Raphanus sativus cv. Rebel and cv. Bolide) seeds in relation to the content of glucosinolates (GLS), vitamin C and total antioxidant capacity was carried out in order to maximise the health-promoting properties of Brassica sprouts. The content of total and individual GLS varied between species, among cultivars, and germination time. Glucoraphanin in broccoli and glucoraphenin in radish were the predominant GLS in raw seeds (61–77 and 63–129 μmol/g DM, respectively) and, although their content decreased during germination, they were maintained in rather large proportions in sprouts. Vitamin C was not detected in raw seeds and its content increased sharply in broccoli and radish sprouts (162–350 and 84–113 mg/100 g DM, respectively). Raw brassica seeds are an excellent source of antioxidant capacity (64–90 and 103–162 μmol Trolox/g DM in broccoli and radish, respectively) and germination led to a sharp increase. Germination of broccoli cv. Belstar and radish cv. Rebel for 4 days provided the largest glucoraphanin and glucoraphenin content, respectively, and also brought about large amounts of vitamin C and antioxidant capacity.     

Simultaneous evaluation of intact glucosinolates and phenolic compounds by UPLC-DAD-MS/MS in Brassica oleracea L. var. botrytis

A method for the simultaneous determination of intact glucosinolates and main phenolic compounds (flavonoids and sinapic acid derivatives) in Brassica oleracea L. var. botrytis was proposed. A simplified sample extraction procedure and a UPLC separation were carried out to reduce the total time of analysis. B. oleracea samples were added with internal standards (glucotropaeolin and rutin), and extracted with boiling methanol. Crude extracts were evaporated under nitrogen, redissolved in mobile phase and analysed by UPLC with double detection (ESI⁻-MRM for glucosinolates and flavonoids, and DAD for main sinapic acid derivatives). The proposed method allowed a satisfactory quantification of main native sinapic acid derivatives, flavonoids and glucosinolates with a reduced time of analysis.     

Phytohormonal and metabolism analysis of <i>Brassica rapa</i> L. ssp. <i>pekinensis</i> with different resistance during <i>Plasmodiophora brassicae</i> infection

Clubroot of Chinese cabbage (Brassica rapa L. ssp. pekinensis), caused by the obligate parasite Plasmodiophora brassicae, accounts for serious yield losses. The aim of our study was to explore the phytohormone levels and metabolome changes in the roots of resistant and susceptible B. rapa genotypes at a late stage of infection, i.e., 28 days post-infection. Both genotypes showed decreased auxin levels after P. brassicae infection except for indole-3-acetic acid. Overall, the susceptible genotype had higher auxin and cytokinin levels after infection, with the exception of trans-zeatin and 3- indolebutyric acid as compared to the resistant genotype. Jasmonic acid levels declined after infection regardless of the genotype. Resistance against clubroot was evident with the increased levels of salicylic acid in the resistant genotype. The susceptible genotype had a higher number of differentially accumulated metabolites (DAMs) (262) than the resistant genotype (238) after infection. Interestingly, 132 DAMs were commonly detected in both genotypes when infected with the pathogen, belonging to metabolite classes such as phenolic acids, amino acids, and derivatives, glucosinolates, organic acids, flavonoids, nucleotides and derivatives, and fatty acids. The differential metabolite analysis revealed that metabolites related to amino acid biosynthesis, fatty acid biosynthesis and elongation, glutathione metabolism, and glucosinolate metabolism were highly accumulated in the resistant genotype, suggesting their essential roles in resistance against P. brassicae infection.     

Jasmonic Acid-Induced Changes in <Emphasis Type="BoldItalic">Brassica oleracea</Emphasis> Affect Oviposition Preference of Two Specialist Herbivores

Jasmonic acid (JA) is a key hormone involved in plant defense responses. The effect of JA treatment of cabbage plants on their acceptability for oviposition by two species of cabbage white butterflies, Pieris rapae and P. brassicae, was investigated. Both butterfly species laid fewer eggs on leaves of JA-treated plants compared to control plants. We show that this is due to processes in the plant after JA treatment rather than an effect of JA itself. The oviposition preference for control plants is adaptive, as development time from larval hatch until pupation of P. rapae caterpillars was longer on JA-treated plants. Total glucosinolate content in leaf surface extracts was similar for control and treated plants; however, two of the five glucosinolates were present in lower amounts in leaf surface extracts of JA-treated plants. When the butterflies were offered a choice between the purified glucosinolate fraction isolated from leaf surface extracts of JA-treated plants and that from control plants, they did not discriminate. Changes in leaf surface glucosinolate profile, therefore, do not seem to explain the change in oviposition preference of the butterflies after JA treatment, suggesting that as yet unknown infochemicals are involved.