Qualitative and quantitative evaluation of glucosinolates in cruciferous plants during their life cycles

Glucosinolates produced by Brassica species were investigated in relation to biofumigation, a term used to describe the effects some allelochemicals, including glucosinolate derived products, may have on soil-borne pathogens or other herbivores. Four Brassica species of the U-triangle, namely B. nigra (L.) Koch, B. carinata Braun, B. juncea (L.) Czern. and B. rapa L. were compared with respect to their qualitative and quantitative glucosinolate profiles in roots, stems, leaves and reproductive organs. Plants were monitored at four different development stages and the total glucosinolate content as well as their dry matter production as an indication of their potential biomass under field conditions were determined. Glucosinolate levels of up to 120 ìmol g -1 DM were found in B. nigra and B. juncea, while B. rapa did not show values over 25 ìmol g-1 DM at any stage of the investigated plant life cycles. In the three species at the top of U-triangle, reproductive tissues showed the highest glucosinolate concentration when compared to the rest of the plant parts, while in B. rapa, the roots were the organs with the highest glucosinolate concentration. The glucosinolate profile of the different plant parts of the species studied changed during the growth cycle, showing that the trade-off between glucosinolate profile and biomass production should be optimized in order to maximize the biofumigation effect of a crop. However, further information on other allelochemicals and on the different types of glucosinolate derived products resulting from autolysis or myrosinase catalyzed hydrolysis of glucosinolates at different reaction conditions is needed for the appropriate description of the potential biofumigation effects of different crops

Processing-bioprocessing of oilseed rape in bioenergy production and value added utilization of remaining seed components

Cruciferous oilseed crops accumulate relatively high concentrations of oil, proteins and dietary fibres (DF) in their seeds, in addition to bioactive components as glucosinolates and myrosinase isoenzymes (thioglucohydrolase; EC 3.2.1.147). When mixed in the presence of moisture, myrosinase isoenzymes and associated components transform glucosinolates into various types of products, which reduces the value of the extracted oil and the remaining seed components, as well as producing unwanted environmental effects due to smell and toxicity. This gives a need for special care concerning myrosinase inactivation as the initial step during processing of oilseed rape, including technologies applied for biodiesel/bioenergy production. The myrosinase inactivation is thus a critical processing step, which needs to be performed at conditions with limited negative effects on other seed components, including proteins and glucosinolates. New bioprocessing technologies are now developed at levels that allow technology transfer from laboratory scale through pilot plant to industrial scale. The extraction of glucosinolates from the seed components remaining after oil separation-pressing and/or extraction is technically possible and has proven successful with the use of bioprocessing technologies. This is also the case concerning isolation of active myrosinases. The possibilities therefore exist for extraction and formulation of glucosinolates as “natural product derived” food and plant protection agents. With the great amounts of partly de-oiled rapeseed meal resulting from bioenergy/biodiesel production, the new bioprocessing technologies call thus for attention in relation to environmental friendly production of food (vegetable oil, protein and DF products), feed and other non food products

Effect of Dietary Fibre Fractions on <i>In Vitro</i> Digestibility of Rapeseed Napin Proteins

Protein digestibility may be influenced by the presence of dietary fibre affecting the nutritional quality of a feed or food product. This study investigated the interplay between rapeseed (Brassica napus L.) protein and fibre constituents separated by industrially scalable pilot plant processing and recombined in mixed samples. Total dietary fibre (TDF) fractions were isolated from rapeseed hulls (TDF-RH) and purified rapeseed embryo fibres (TDF-RE). The effect of TDF sources on in vitro protein digestibility (IVPD) of a rapeseed protein concentrate rich in napin proteins (RP2) was assessed at three inclusion levels (200, 333, and 500 mg/g DM) using a sequential transient proteolysis by pepsin (1 h) and pancreatin (1 h). The IVPD of RP2 was dose-dependently decreased upon addition of hull fibres at all inclusion levels (8.9-26.6%; P<0.05), whereas the effect of embryo fibres was of a markedly lower magnitude and only significant at the medium to high levels (7.3-8.9%; P<0.05). These results demonstrated that TDF fractions obtained from rapeseed differentially affect the protein digestibility of rapeseed napin proteins depending on the fibre source and inclusion level