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Nutritional quality of vegetables is affected by several steps in the food chain. Up to now the effects of these different steps are mostly studied separately. We propose the cooperation between plant breeding and food technology by using food technological parameters as breeding traits to identify genetic loci associated with food processing. An example of mechanistic studies of glucosinolate losses during cooking is used to discuss requirements, possibilities, challenges and benefits of such an integrated approach with the final aim to breed for vegetables with higher retention of glucosinolates, as example for other phytochemicals, during food processing.

Scope: To study the effect of residual myrosinase (MYR) activity in differently processed broccoli on sulforaphane (SR) and iberin (IB) formation, bioavailability, and excretion in human volunteers. Methods and results: Five different broccoli products were obtainedwith similar glucoraphanin (GR) and glucoiberin (GI) content, yet different MYR activity. Excretion of SR and IB conjugates in urine were determined in 15 participants after ingestion of the broccoli products. A reduction of 80% of MYR in the product did not cause differences in the total amount of SR and IB found in urine compared to the product with 100% MYR. Complete inactivation of MYR gave the lowest total amount of SR and IB in urine (10 and 19%). A residual MYR of only 2% in the product gave an intermediate amount (17 and 29%). The excretion half-lives of SR and IB conjugates were comparable for all the products (2.5 h on average), although the maximum excretion peak times were clearly shorter when the residual MYR was higher (2.3–6.1 h). Conclusion: For the first time, the effect of residual MYR activity on isothiocyanate bioavailability was systematically and quantitatively studied. Processing conditions have a large effect on the kinetics and bioavailability of isothiocyanates from broccoli.

Glucosinolates (GSs) are secondary metabolites of Brassica vegetables that are associated with health benefits. The concentrations of these compounds are strongly affected by processing of the vegetables. During thermal treatment of Brassicaceae, such as domestic cooking, different mechanisms affecting the content of GSs can take place and were modeled in the present study: Lysis of plant cells and compartments, leaching of GSs into the cooking water and thermal degradation of GSs in both the intact vegetable tissue and the cooking water. These mechanisms were described mathematically and the model parameters for broccoli, Brussels sprouts, red cabbage and white cabbage were estimated based on experimental results. Differences between the thermostability of the same GSs originating from different Brassicaceae could be detected, as well as differences between the thermostability of the same GSs in the vegetable matrix compared to that in the cooking water. Industrial relevance This mathematical model and the estimated parameters can be used to simulate the different glucosinolate contents in prepared foods considering the processing method. This will be a very useful tool for food research and industry to make predictions about the nutritional quality of foods and to optimize their health related quality attributes.

Glucosinolates (GLSs), health promoting compounds commonly found in Brassica vegetables, were studied during sayur asin fermentation made from Indian mustard (B. juncea). The current preliminary study aims to investigate the changes of glucosinolates content during 3 and 7 days of fermentation in two different media, i.e. coconut water and tajin liquor, and salt concentrations of 2.5 and 10%. The glucosinolates were analysed by HPLC after sample extraction in hot methanol followed by purification and de-sulphation. Results show that sinigrin was the most dominant glucosinolate among others, i.e. gluconapin, glucobrassicin, 4-hydroxy-glucobrassicin, 4-methoxy-glucobrassicin, and neo glucobrassicin, accounting for about 1000 and 4000 µmol/10 g dw in raw Indian mustard. Unfortunately, fermentation has substantially reduced the glucosinolates content in sayur asin. After 3 days of fermentation the sinigrin content was reduced by 95% as compared to that in the raw vegetable. The indole GLSs 4-methoxy-glucobrassicin and neo-glucobrassicin concentration decreased to 80-90% of the fresh materials. However, the decreasing mechanisms as well as factors contributing to the decrease of the glucosinolates could not be explained yet.

The domestic preparation of vegetables induces a significant change in their sensory and health attributes. The preparation of vegetables by consumers is likely to be controlled by assessing perceivable (sensory) quality attributes such as colour and texture because other quality attributes, including the phytochemical content (health), cannot be directly assessed. ‘Consumer-Oriented Food Technology’ is introduced herein as a research approach for the ‘multi-criteria optimisation’ of vegetable quality after domestic preparation. Mathematical modelling for ‘multi-criteria optimisation’ is proposed as a tool to meet consumer sensory preferences while optimising health benefits. This approach is valuable for consumer-based strategies for healthy, tasty vegetables.

Epidemiological and mechanistic studies show health-promoting effects of glucosinolates and their breakdown products. In literature, differences in non-enzymatic glucosinolate degradation rates during food processing between different vegetables are described, which provide the basis for studying the genetic effects of this trait and breeding vegetables with high glucosinolate retention during food processing. Non-enzymatic glucosinolate degradation, induced by heat, was studied in a publicly available Brassica oleracea doubled haploid population. Data were modeled to obtain degradation rate constants that were used as phenotypic traits to perform quantitative trait loci (QTL) mapping. Glucosinolate degradation rate constants were determined for five aliphatic and two indolic glucosinolates. Degradation rates were independent of the initial glucosinolate concentration. Two QTL were identified for the degradation rate of the indolic glucobrassicin and one QTL for the degradation of the aliphatic glucoraphanin, which co-localized with one of the QTL for glucobrassicin. Factors within the plant matrix might influence the degradation of different glucosinolates in different genotypes. In addition to genotypic effects, we demonstrated that growing conditions influenced glucosinolate degradation as well. The study identified QTL for glucosinolate degradation, giving the opportunity to breed vegetables with a high retention of glucosinolates during food processing, although the underlying mechanisms remain unknown.

BACKGROUND: Kales are often a key ingredient of traditional foods, containing high amounts of indolic glucosinolates (precursors of indole-3-carbinol and ascorbigen), carotenoids and phenolics. The present trend to associate traditional foods crops with health-promoting properties suggested to investigate the degradation kinetic of three Brassica oleracea landraces' phytochemicals subjected to boiling, steaming and stir-frying. RESULTS: Boiling led to substantial losses due to leaching. Glucosinolates followed a second-order degradation kinetic (20% of their initial values after 10 min in Nero di Toscana). Phenolic content in leaves + cooking water remained unchanged, whereas their antioxidant capacity was reduced. Carotenoid content increased during the first minutes of boiling. Steaming showed the highest retention of phytochemicals, with often zero-order degradation kinetic, having however a strong effect on colour. Stir-frying produced high losses for all measured compounds; also, β-carotene reduced its content to 10–23% independently of variety. Conversion values for indole-derived compounds ranged from non-detectable to 23.5%. CONCLUSION: Variety strongly affected observed degradation rates because of a different glucosinolate composition and leaf structure. With this research, more information has been gained on the degradation kinetic of B. oleracea landraces' phytochemical compounds upon cooking, highlighting the possibility of improving bioactive component retention. © 2016 Society of Chemical Industry.

Steaming has been reported to better retain the glucosinolate (GS) content in Brassica vegetables than boiling. However, there is little information on the GS content, colour, and texture attributes in Brassica vegetables in relation to the duration of steaming. This study investigated the effect of the duration of steaming, which was applied in certain commercial preparation processes, on the GS content, colour, and texture of white cabbage. Results showed that the total accessible content of GSs increases initially during steaming until 10 min followed by a consistent decline up to 180 min. This observed initial increase is mainly due to the content of aliphatic GSs rather than indole GSs, which tend to decrease from the start of steaming. A mathematic model for the observed behaviour of the GSs, taking into account several mechanisms, is proposed and fitted to the data. The intensity of the green colour of the cabbage slightly increased during the first 15 min of steaming followed by a decrease onwards. The hardness showed a continuous decline during the entire steaming duration. The study indicates that steaming up to 10 min could promote the health properties as well as the colour and texture attributes of steamed cabbage.

Kinetic modeling was used as a tool to quantitatively estimate glucosinolate thermal degradation rate constants. Literature shows that thermal degradation rates differ in different vegetables. Well-characterized plant material, leaves of broccoli and Chinese kale plants grown in two seasons, was used in the study. It was shown that a first-order reaction is appropriate to model glucosinolate degradation independent from the season. No difference in degradation rate constants of structurally identical glucosinolates was found between broccoli and Chinese kale leaves when grown in the same season. However, glucosinolate degradation rate constants were highly affected by the season (20-80% increase in spring compared to autumn). These results suggest that differences in glucosinolate degradation rate constants can be due to variation in environmental as well as genetic factors. Furthermore, a methodology to estimate rate constants rapidly is provided to enable the analysis of high sample numbers for future studies.

The kinetics of the thermal degradation of vitamin C of marula, mango and guava pulp at different heat treatments at temperature ranging from 80 to 150 °C were investigated. For temperatures lower than 125 °C, the ascorbic acid in marula pulp was about 15 fold more stable to heat than the ascorbic acid in mango and guava pulp. The results showed that a simple first order degradation model could not describe the vitamin C degradation as biphasic behaviour was observed. Therefore the model was transformed in a two-fraction model in which the vitamin C content is divided in relatively stable and instable fractions. Marula had a low kd1,100°C of 7.2 × 10−3 min−1 compared to kd1,100°C of 1.2 × 10−1 min−1 for guava and 1.3 × 10−1 min−1 for mango. Guava had the highest activation energy, Ea of 58 kJ/mol, followed by mango with 39 kJ/mol and then marula with 29 kJ/mol.

The effect of water content and temperature on glucosinolate thermal degradation in broccoli ( Brassica oleracea var. italica ) was investigated. Broccoli was freeze dried obtaining batches with water content between 13% and 82% ( a w from 0.32 to 0.99). These samples were heated at different temperatures (from 60 to 120 °C) and glucosinolate levels were monitored. To rule out enzymatic breakdown, myrosinase was inactivated prior to heating. Degradation could be described by first-order kinetics for all glucosinolates and all water contents. In the temperature range 60–100 °C the sample with 13% showed the lowest degradation rate, whereas at 120 °C the degradation rate increased with the water content. This particular behavior was reflected by the high activation energy value of the driest sample. Several hypotheses to explain the observed behavior are discussed.

Glucosinolates are phytochemicals with health promoting properties. Determination as desulpho-glucosinolates is widely used and a desulphation in microtiter plates has been applied to reach high throughput. The use of various sulphatase concentrations and volumes throughout literature necessitates the identification of an appropriate desulphation procedure in microtiter plates. High sulphatase concentrations (⩾15 mg/ml) decreased the concentration of the internal standard glucotropaeolin, whereas the other glucosinolates were less affected. Due to the calculation based on the recovery of glucotropaeolin, this leads to an overestimation of GL concentrations after desulphation with high sulphatase concentrations. A glucosidase side-activity, present in the crude sulphatase powder, is likely causing this phenomenon. At lower sulphatase concentrations (1 mg/ml) glucoiberin and glucoraphanin were insufficiently desulphated. Combining these effects results in a small range of applicable sulphatase concentrations. A purified sulphatase preparation resulted in good recoveries for a diversity of samples and is hence recommended for high throughput desulphation in microtiter plates.

Brassica vegetables are the predominant dietary source of glucosinolates (GLS) that can be degraded in the intestinal tract into isothiocyanates, which have been shown to possess anticarcinogenic properties. The effects of pilot-scale long-term boiling on GLS in white cabbage (Brassica oleracea L. ssp. capitata f. alba cv. `Bartolo¿) was experimentally determined and mathematically modeled. Cabbage was boiled, resulting in a dramatic decrease of 56% in the total GLS levels within the plant matrix during the first 2 min. After 8¿12 min of boiling, the decrease progressed to over 70%. Progoitrin had an exceptionally higher decline rate in comparison to all other GLS. As boiling progressed the concentration of all GLS continued to decrease at a lower rate for the remaining cooking period. A mathematical model was used to describe the concentration profile of the GLS in the plant matrix, based on leaching of GLS to the water phase due to cell lysis and thermal degradation of the GLS both in the plant matrix and in the water phase. The model described the concentration profiles very well. Estimated lysis and degradation rate constants for white cabbage differed from those reported in the literature for red cabbage. The degradation rate constants found were significantly higher in the plant matrix when compared to those in the water phase for all GLS. Identification of the kinetics of decline of GLS during cooking can aid in designing processing and preparation methods and determining the conditions for the optimal effects of ingestion of Brassicaceae toward cancer prevention.

Food preparation practices are known to have large nutritional implications on the final product. This article describes survey data on preparation practices of Brassica vegetables and the translation of these data into technological and nutritional implications using knowledge on the mechanisms of changes in the content of phytochemicals. The survey on preparation practices was performed with food service establishments (n¿=¿123) and households (n¿=¿477) in Semarang, Indonesia, and assessed the food handlers’ perception of the health benefits of these vegetables. Boiling and stir-frying are the most frequently applied techniques to prepare Brassicas. The respondents perceive that steaming, boiling, and stir-frying result in vegetables with a high health benefit. White cabbage and choysum are the most frequently prepared Brassicas. However, broccoli is perceived as the healthiest. The consequences of the various applied preparation techniques on the content of alleged health promoting phytochemicals (glucosinolates) in dishes containing Brassica vegetables are discussed.

Brassica vegetables are consumed mostly after processing, which is expected to give beneficial effects on the vegetable properties, such as improved palatability and bioavailability of nutrients, or shelf life extension. But processing also results to various changes in the content of health promoting phytochemicals like glucosinolates. This paper reviews the effects of processing on the glucosinolates content by using a mechanism approach underlying processing method employed. Cultural differences between Eastern and Western preparation practices and their possible effect on glucosinolate retention are highlighted. Boiling and blanching considerably reduce the glucosinolate content mainly due to mechanisms of cell lysis, diffusion, and leaching, and partly due to thermal and enzymatic degradation. Steaming, microwave processing, and stir frying either retain or slightly reduce the glucosinolates content due to low degrees of leaching; moreover, these methods seem to enhance extractability of glucosinolates from the plant tissue. Fermentation reduces the glucosinolate content considerably, but the underlying mechanisms are not yet studied in detail. Studying the changes of glucosinolates during processing by a mechanistic approach is shown to be valuable to understand the impact of processing and to optimize processing conditions for health benefits of these compounds.

Glucosinolate (GL) stability has been widely studied in different Brassica species. However, the matrix effect determined by the presence of other ingredients occurred in many broccoli-based traditional recipes may affect GL thermal degradation. In this study, the matrix effect on GL thermal degradation was investigated by means of binary systems containing broccoli and another ingredient such as potato, corn starch, lentils protein or onion. Data showed that in binary systems the GL degradation was lower compared to the only-broccoli system, in particular in the broccoli/onion systems. The kinetics of GL degradation in broccoli/onion systems at different ratios showed that the higher the amount of onion, the higher the protective effect and that GL thermal degradation followed a second order model. Finally the possibility that the effect was related to the amount of flavonoids present in onions was ruled out by data obtained using broccoli/onion systems made with three onion varieties having different flavonoid content. This study shows for the first time that the presence of other food ingredients can efficiently reduce GL thermal degradation. The protective effect of onion, often present in the traditional recipes of broccoli soups in many countries, points out that the interaction of different ingredients may not only improve the taste of a dish, but also the healthiness.

Food product development needs to be based on consumers' needs and wishes to be successful. Factors that have become relevant in this respect are presented and their impact discussed, like mass-individualization, globalization and an altered interpretation of the food quality concept by consumers. Finally, structured approaches that can aid in the process of consumer-driven food product development are given.

Total and individual levels of glucosinolates (GSs) were measured in red cabbage after various microwave treatments varying in time and intensity of the treatments. Furthermore, the myrosinase enzyme activity of the microwave-heated vegetables was determined. The retention of GSs in the cabbage and the residual activity of the hydrolytic enzyme as a result of microwave preparation were compared with untreated cabbage. In general, high total GS levels were observed for all of the applied microwave treatments. Strikingly, many of the time/energy input combinations resulted in levels exceeding the total GS content of the untreated cabbage material. Moreover, the increase in levels seems to be associated with the energy input applied. A possible explanation for this behavior is an increased extractability of GS from heat-treated cabbage as compared to raw cabbage. Substantial myrosinase activity was retained in cabbage treated at low (24 min, 180 W) and intermediate microwave powers (8 min, 540 W) while microwave cooking for 4.8 min at 900 W (259.2 kJ energy input) resulted in a complete loss of hydrolytic activity. In this respect, differences in observed temperature profiles of the various microwave treatments play an important role. Higher retention of GSs and controllable amounts of active myrosinase can offer increasing health-promoting properties of microwave-prepared Brassica vegetables.

Background: Many epidemiological studies have tried to associate the intake of certain food products with a reduced risk for certain diseases. Results of these studies are often ambiguous, conflicting, or show very large deviations of trends. Nevertheless, a clear and often reproduced inverse association is observed between total vegetable and fruit consumption and cancer risk. Examples of components that have been indicated to have a potential protective effect in food and vegetables include antioxidants, allium compounds and glucosinolates. Aim: The food production chain can give a considerable variation in the level of bioactive components in the products that are consumed. In this paper the effects of this variability in levels of phytochemicals in food products on the sensitivity of epidemiological studies are assessed. Methods: Information on the effect of variation in different steps of the food production chain of Brassica vegetables on their glucosinolate content is used to estimate the distributions in the levels in the final product that is consumed. Monte Carlo simulations of an epidemiological cohort study with 30,000 people have been used to assess the likelihood of finding significant associations between food product intake and reduced cancer risk. Results: By using the Monte Carlo simulation approach, it was shown that if information on the way of preparation of the products by the consumer was quantified, the statistical power of the study could at least be doubled. The statistical power could be increased by at least a factor of five if all variation of the food production chain could be accounted for. Conclusions: Variability in the level of protective components arising from the complete food production chain can be a major disturbing factor in the identification of associations between food intake and reduced risk for cancer. Monte Carlo simulation of the effect of the food production chain on epidemiological cohort studies has identified possible improvements in the set up of such studies. The actual effectiveness of food compounds already identified as cancer-protective by current imprecise methods is likely to be much greater than estimated at present.

The aim of this study was to investigate the chemopreventive effects of widely consumed cruciferous vegetables, namely Brussels sprouts and red cabbage towards 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced preneoplastic lesions [liver glutathione-S-transferase placental positive (GST-P(+)) foci and colonic aberrant crypt foci (ACF)]. Male F344 rats were treated with IQ (100 mg/kg bw/g) on 10 alternating days and received drinking water supplemented with Brussels sprouts and red cabbage juices (5% v/v) before and during the carcinogen treatment. From each vegetable two different cultivars were tested. Brussels sprouts reduced the frequency of IQ-induced aberrant foci in both organs (41-52% in the colon and 27-67% in the liver). Also, Brussels sprouts drastically diminished (85-91%) the size of liver GST-P(+) foci, but no such effect was seen in the colon. With red cabbage, the size of liver GST-P(+) foci was markedly reduced (41-83%) whereas the foci frequency was only moderately decreased (19-50%). No protection was seen in the colon after treatment with red cabbage. Cooking (10 min, 100 degrees C) of the vegetables had no influence on their protective effects. The stronger chemoprotective effects of Brussels sprouts may be due to the fact that the overall glucosinolate contents were substantially (2-3-fold) higher than those of the cabbage cultivars, but it was not possible to attribute the reduction of preneoplastic lesions to specific glucosinolates. The activities of hepatic UDP-glucuronosyltransferase form 2 (UDPGT-2) and cytochrome P4501A2 were increased by both vegetables. The induction effect of Brussels sprouts on the activity of UDPGT-2 was more marked than that of the red cabbage cultivars, suggesting that increased glucuronidation of IQ may account for the reduction of the preneoplastic lesions. Our findings support the assumption that Brassica vegetables protect against the carcinogenic effects of heterocyclic amines.

Background: Preferences for sensory properties (e.g. taste and texture) are assumed to control cooking behaviour with respect to vegetables. Conditions such as the cooking method, amount of water used and the time-temperature profile determine the nutritional quality (e.g. vitamins and phytochemicals) of cooked vegetables. Information on domestic processing and any underlying motives can be used to inform consumers about cooking vegetables that are equally liked and are nutrient-rich. Methods: Two online self-reporting questionnaires were used to identify domestic processing conditions of broccoli and carrots by Dutch households. Questions on various aspects of domestic processing and consumer motives were included. Descriptive data analysis and hierarchical cluster analysis were performed for both vegetables, separately, to group consumers with similar motives and behaviour towards vegetables. Results: Approximately 70% of consumers boiled vegetables, 8–9% steamed vegetables, 10–15% stir fried raw vegetables and 8–10% stir fried boiled vegetables. Mainly texture was used as a way to decide the ‘doneness’ of the vegetables. For both vegetables, three clusters of consumers were identified: texture-orientated, health-orientated, or taste-orientated. The texture-orientated consumers are identified as the most prevalent (56–59%) group in the present study. Statistically significant associations are found between domestic processing conditions and clusters, whereas no such association are found between demographic details and clusters. Conclusions: A wide variation in domestic processing of broccoli and carrots is found in the present study. Mainly sensory properties (i.e. texture and taste) determined the domestic processing conditions. The findings of the present study can be used to optimise cooking to yield vegetables that meet consumer’s specific sensory preference and are higher in nutrients, and as well as to communicate with target consumer groups.

This study examined the influences of domestic processing conditions applied by consumers on firmness, colour and amount of phytochemicals and liking and sensory attributes intensity rating of carrots. The aim was to identify a cooking method and time that yields carrots with higher amount of β-carotene while maintaining consumer liking. Instrumentally measured firmness and colour showed comparable degradation trends between cooking methods. While boiling showed a significant decrease in the amount β-carotene after 20 min (−19%), steaming maintained the amount (+40%). Cooking method did not show a significant effect on liking and intensity ratings for the majority of the sensory attributes. Medium firm carrots were liked the most and low firm carrots the least. This study demonstrates that for optimum liking, carrots should be in the range of medium firmness. This can be obtained through either cooking methods but steamed carrots possess a higher amount of β-carotene and maintains liking.

This paper reviews the main results of EU-action: “COST 926: Impact of new technologies on the health benefits and safety of bioactive plant compounds”. The bioavailability and the effects on gene expression of various bioactive components in plant foods are described in relation with their implication for human health. The objective of this study was to gain insights into the effect of the cooking method on the liking as well as the retention of glucosinolates in broccoli. With this knowledge it can be concluded whether the health aspects of broccoli be improved by the cooking method without deteriorating sensory perception. For this, broccoli was cooked by methods commonly applied by consumers: boiling with a cold (water) start; boiling with a hot (water) start; and steaming. Firmness, greenness and amount of total glucosinolates in cooked broccoli were instrumentally determined. Sensory evaluation by untrained consumers (n¿=¿99) for liking and sensory attributes intensity rating were performed on broccoli cooked by steaming and boiling-cold start at three time points, which resulted in ‘high’, ‘medium’, ‘low’ firm broccoli samples. At the end of cooking, steaming showed an increase in the amount of total glucosinolates (+17 %). Boiling-hot start (-41 %) and boiling-cold start (-50 %) showed a decrease in amount of total glucosinolates. Sensory evaluation did not show statistically significant differences between steaming and boiling-cold start in liking at ‘high’ and ‘medium’ firmness; and in the attribute intensity ratings (except for juiciness at ‘medium’ firmness, and flavour at ‘medium’ and ‘low’ firmness). This study demonstrates that medium firm broccoli showed optimum liking and that steaming compared to boiled-cold start showed higher amount of glucosinolates. It is concluded that the health aspects of broccoli can be improved without reducing the sensory aspects by optimising the cooking method.

This paper reviews the main results of EU-action: “COST 926: Impact of new technologies on the health benefits and safety of bioactive plant compounds”. The bioavailability and the effects on gene expression of various bioactive components in plant foods are described in relation with their implication for human health.

Texture is an important product property that strongly affects the quality evaluation of processed vegetables by consumers. The rate of texture decrease is dependent on the processing temperature and the type of vegetable. A large data set on instrumental texture measurements of carrot and broccoli was produced with different time–temperature combinations for steaming the vegetables. This data set was fitted with a fractional conversion model to describe the kinetics of texture change. Pre-treating the vegetables by steaming at 50–80 °C can increase the resistance towards softening in a subsequent steaming process. The effect of time and temperature of the thermal pre-treatment on the rate constant of softening during subsequent steaming has been evaluated. A response surface two factor interaction model could well describe this effect. Pre-treatments enable more flexibility to optimise several product properties like health, texture and colour. The predictive model presented here is a valuable tool for this multi-criteria optimisation. Industrial relevance A model to describe the softening of vegetable texture during steaming is presented, and the effect of pre-treatment conditions on the reduction of the subsequent softening rate is included in the model. With this model vegetable texture can be improved by predicting the optimal time and temperature of the pre-treatment. This model can be integrated into a multi-criteria optimization approach to improve other quality attributes and still give a desired texture.

This review critically evaluated literature on proximate composition and nutritional value of Marula in comparison with other tropical and indigenous fruits in order to identify areas for future research. It was found that nutrients content and processing methods of Marula fruit varied greatly from study to study and according to place of origin, soil, climate, handling, analytical methods used and time that lapsed after harvesting before analysis took place. Marula fruit pulp is reported to have vitamin C content higher than that of most fruits, ranging from 62 mg/100 g to over 400 mg/100 g. Additionally, Marula fruit is reported to have an antioxidant capacity of between 8 and 25 mM, (ascorbic acid equivalents) and a total phenolic content ranging from 7.5 to 24 mg/g dry weight gallic acid equivalent. Marula kernels are also a good source of protein, oil, magnesium, phosphorus and potassium and their oil is used in food preparations. Marula fruits could play a vital role in terms of nutrition to rural community who rely on the usage of the fruits, as they do not have easy access to other sources of nutrients. Recommendation given for future research includes improving Marula fruits juice extraction and yields, investigating the effect of processing and storage on the retention of nutrients such as vitamin C and its antioxidant capacity in processed and unprocessed Marula products and further identifying Marula fruits flavor compounds and their effect on processing and storage.

This work concerns the degradation of the nutritional compounds glucoraphanin (GR) and vitamin C (Vc), and the inactivation of the enzyme myrosinase (MYR) in broccoli ( Brassica oleracea var. italica ) during drying with air temperatures in the range of 30–60 °C. Dynamic optimization is applied to find the optimized temperature trajectories that minimize degradation and inactivation. Simulation and experimental results for optimized temperature trajectories are compared to constant inlet air temperature drying at 40 and 50 °C. The results show that with the optimized temperature trajectories the retention of GR, MYR and Vc improved significantly. Moreover, the experiments show that degradation and inactivation during drying is slower than expected from kinetic studies. The deviation is explained from the difference in the physical state of the samples used in the drying experiments, i.e. original plant tissue versus the grounded state of the plant tissue used in the experiments for the kinetic studies. The results indicate that besides temperature and moisture content the physical state is also an important aspect in the degradation of nutritional compounds and enzymes.

Brassica vegetables contain high amounts of glucosinolates, which contribute to the beneficial health effects of their consumption. Processing of such vegetables in domestic food preparation or industrial processing will influence levels of glucosinolates considerably and thus affect their health-protective capacity. This study demonstrates the effects of chopping of raw Brassica vegetables on their glucosinolate composition. Limited breakdown of aliphatic glucosinolates in cabbage was found, whereas unexpected increased levels of indolyl glucosinolates were detected after chopping and storage of cabbage and broccoli under ambient conditions. In chopped white cabbage a 15-fold increase of 4-methoxy- and l-methoxy-3-indolylmethyl glucosinolates was noted after 48h of storage. Chopping and storage of broccoli resulted in a strong reduction of most glucosinolates, except for 4-hydroxy- and 4-methoxy-3-indolylmethyl glucosinolates, which increased 3.5- and 2-fold respectively. The myrosinase-mediated hydrolysis of glucosinolates appears to be counteracted by a post-harvest increase of some indolyl glucosinolates. In this paper we propose a mechanism of stress-induced increase of glucosinolates, which plays an important role besides the well-known breakdown mechanism. L'effet du tranchage sur la composition des choux crus en glucosinolates est etudie. Les taux de glucosinolates d'indole augmentent apres entreposage et tranchage dans le chou et le brocoli. Les glucosinolates totaux dans le chou coupe proviennent probablement de la degradation par la myrosinase d'une part et de la formation des indoles induite par le stress, d'autres part.

The glucosinolates are a large group of sulphur-containing compounds which occur in all the economically important varieties of Brassica vegetable. Their common structure comprises a β-D-thioglucose group, a sulphonated oxime moiety and a variable side-chain derived from methionine, tryptophan or phenylalanine. When the plant tissue is damaged the glucosinolates are hydrolysed by the endogenous enzyme ‘myrosinase’ (thioglucoside glycohydrolase EC 3:2:3:1), to release a range of breakdown products including the bitter, biologically active isothiocyanates. Although these compounds exert antinutritional effects in animals there is also substantial evidence that they are the principal source of anticarcinogenic activity in Brassica vegetables, and this provides a strong motive for the manipulation of glucosinolate levels in vegetables for human consumption. This review provides an overview of the evidence for a beneficial role for glucosinolates in human health, and describes the current state of knowledge regarding the genetics and biosynthesis of glucosinolates, their chemical analysis, their behaviour during cooking and processing, and their bioavailability to humans. As the genetic basis of glucosinolate biosynthesis becomes more apparent, and tools for marker-assisted plant breeding become more available, the selective breeding of horticultural brassicas with different levels and types of glucosinolates, whether by conventional means or genetic manipulation, is becoming a practical possibility. However before this strategy becomes commercially viable, the health benefits of glucosinolates for human beings must be unequivocally established. © 2000 Society of Chemical Industry

In this paper, it is demonstrated that many steps in the food production chain of vegetable products can have large influence on the final intake of health protective phytochemicals. The wide variations in levels at each step in the production chain makes an experimental quantification of the dietary intake of phytochemical extremely difficult. We present a concept for predictive modelling of the effects of various processes in the production chain of vegetable products on the intake of phytochemicals with potential health benefits. This approach is intended to be used for the developments of tools to facilitate both product and process development for health products as well as epidemiological input data for bioactive substances in the diet. Protective glucosinolates present in Brassica vegetables are used to illustrate the value of such a predictive model. The described model provides a powerful tool for handling the variation of glucosinolate levels throughout the chain in a quantitative way. Product development, consumer advice and human intervention trials are important areas that could benefit enormously from this approach.

This article describes a set of protocols—for retrofitting, transformation and purification—that together enable the delivery of full-sized YAC-DNA to plant cells. To be able to equip YACs of interest with plant selectable markers, we have constructed a retrofitting vector that carriesnptII anduidA. Furthermore, we established a transformation protocol for plant protoplasts that is sufficiently efficient to support transfer of high-molecular-weight DNA. In this protocol lipofection is combined with PEG-mediated direct gene transfer. Large amounts of purified DNA are necessary for lipofection. To obtain sufficient quantities of concentrated, purified YAC-DNA, we used an optimized two-step, gel-purification method. Transient expression of a YAC-bornuidA demonstrates that both retrofitting vector and transformation protocol are effective.

The map positions of five previously described phytochrome genes have been determined in tomato (Lycopersicon esculentum Mill.) The position of the yg-2 gene on chromosome 12 has been confirmed and the classical map revised. The position of the phytochrome A (phy A)-deficient fri mutants has been refined by revising the classical map of chromosome 10. The position of the PhyA gene is indistinguishable from that of the fri locus. The putative phyB1-deficient tri mutants were mapped by classical and RFLP analysis to chromosome 1. The PhyB1 gene, as predicted, was located at the same position. Several mutants with the high pigment (hp) phenotype, which exaggerates phytochrome responses, have been reported. Allelism tests confirmed that the hp-2 mutant is not allelic to other previously described hp (proposed here to be called hp-1) mutants and a second stronger hp-2 allele (hp-2 j ) was identified. The hp-2 gene was mapped to the classical, as well as the RFLP, map of chromosome 1.

An approach for process design based on optimization of product quality attributes is presented. Adsorption drying of broccoli with retention of its health benefits is taken as an example to illustrate the approach. Related to its content of glucosinolates, broccoli has a high potential to reduce the risk of some types of cancer. Three products are described with different glucosinolates, myrosinase and isothiocyanates related health profiles. These products require different drying scenarios with specific optimization targets. This viewpoint paper presents a case on quality based process design as an example for broader application onto food products.

Conventional fermentation of cabbage like in sauerkraut production leads to a complete elimination of glucosinolates (GSs). In order to retain GSs in fermented cabbage, the effect of a thermal treatment (blanching) followed by fermentation (4% brine at 25 °C) by the probiotic strain Lactobacillus paracasei LMG P22043, was investigated. After 71 h fermentation the probiotic blanched cabbage still contained 27.2 ± 2.3 μmol/100 g GSs, corresponding to the 35% of the total GSs before fermentation. A final count of L. paracasei of 8.26 ± 1.2 log 10 CFU/g, and a final pH of 4.12 ± 0.1 were reached. After 30 days of refrigerated vacuum packed storage, 23.7 ± 1.5 μmol/100 g of GSs still persisted. In the control cabbage (blanched and not inoculated with L. paracasei ) no fermentation occurred and as a result final pH was 6.10 ± 0.21, leading to a product not suitable for storage and consumption. Compared to traditional sauerkraut the final product has the advantage of containing a high content of phytochemicals in combination with a high count of live probiotic bacterial cells.

This paper presents the effects of fermentation on the retention of vitamin C, total polyphenols and antioxidant activity in the naturally fermented marula juice. The fermentation conditions have been varied: temperature ranged between 20 and 40 °C and fermentation time from 1 to 8 days. Marula juice fermented at higher temperatures ranged between 30 and 40 °C for 6 to 4 days retained high antioxidant activities, and they were positively correlated to its ascorbic acid and phenolic content. The values obtained ranged between 0.0239 ± 0.0051 and 0.029 ± 0.0038 μmol/mg for Trolox Equivalence Antioxidant Capacity, 870 ± 80 and 960 ± 130 mg/100 ml for total phenolic content and 90 ± 6 and 159 ± 15 mg/100 ml for ascorbic acid. Overall, fermented marula juice can be used as a good source for natural antioxidants.

An F2 of an interspecific cross between cultivated tomato (Lycopersicon esculentum cv. Moneymaker) and L. hirsutum f. glabratum was used to generate an RFLP linkage map. Distortion of single locus segregation (1:2:1) was observed for a number of markers from different chromosomes, always with a prevalence for L. hirsutum f. glabratum alleles. To identify quantitative trait loci (QTLs) for greenhouse whitefly (Trialeurodes vaporariorum) resistance in this F2 population, life history components of the greenhouse whitefly population were evaluated. Two QTLs affecting oviposition rate mapped to chromosome 1 (Tv-1) and 12 (Tv-2). F3 lines homozygous for either the L. esculentum allele or the L. hirsutum f. glabratum allele at one or both loci confirmed the effects of Tv-1 and Tv-2. The F2 population was also evaluated for segregation of type IV and type VI glandular trichome densities. Two QTLs affecting trichome type IV density (TriIV-1 and TriIV-2) and one affecting type VI trichome density (TriVI-1) mapped to chromosomes 5, 9 and 1, respectively. These results do not support the hypothesis that the density of type IV trichomes is involved in whitefly resistance.

Glucosinolates are secondary metabolites of Brassica vegetables that have been associated with health benefits. The concentrations of these compounds are strongly affected by processing of the vegetables. Various mechanisms are responsible for these changes: Lysis of plant cells and compartments, diffusion and leaching of glucosinolates and myrosinase (a plant enzyme able to hydrolyze glucosinolates) into the cooking water, enzymatic hydrolysis of glucosinolates, inactivation of myrosinase and thermal degradation of glucosinolates. This publication presents a dynamic mathematical model that includes these mechanisms with their estimated parameters and the effect of temperature on them. Simulations made by the model for several process conditions show losses of glucosinolates as a consequence of domestic boiling of 69%, microwaving of 8%, industrial blanching of 37% and by industrial sterilization of 82%. The model can assist in adapting the processing conditions like the time–temperature profile and the vegetable–water ratio to optimize industrial and domestic processing of Brassica vegetables in terms of health benefits. In addition this model can help to add the effect of vegetable preparation practices on the quantitative glucosinolate intake in epidemiological studies.

In a tomato (Lycopersicon esculentum) breeding programme aimed at earliness, a breeding line, designated ‘IVT-KT1’, was developed by several rounds of crossing and selection. Among its ancestors were the two wild relatives L. pimpinellifolium and L. parviflorum. The breeding line flowered and set fruit one to four weeks earlier than old and modern cultivars. To identify QTLs for earliness, an F2 population was obtained by crossing ‘IVT-KT1’ with the ‘late’ true breeding cultivar ‘Premier’. In winter and early spring, 690 plants of this F2 population were evaluated for earliness of which 292 were selected for RFLP analysis. Only limited parts of the genomes of ‘IVT-KT1’ and ‘Premier’ were polymorphic and these polymorphisms were likely due to introgression from the ancestor wild species. By using the interval mapping method on the combined data of the greenhouse evaluations and RFLP analyses, three loci were identified that were associated with earliness. One was mainly associated with flowering time, another with fruitset time and a third one with ripening time. Two of these loci were also associated with fruit weight. F3 progenies selected for earliness on the basis of the QTL-data did confirm the F2 results. Two major earliness genes explained a difference in earliness of more than three weeks. The association with reduced fruit weight seemed to be due to pleiotropic effects rather than to linked genes. Consequently, the gain in earliness will cause a reduction in fruit weight that may not be acceptable for breeding applications.

Summary The superior regeneration capacity of Lycopersicon peruvianum was introduced into the cultivated tomato Lycopersicon esculentum by backcrossing hybrid material with the tomato genotype VF11. In segregating material derived from these backcrosses, the ability to regenerate shoots on root explants cultured on a zeatin-containing medium, was highly correlated with the ability to regenerate shoots on established callus cultures. The efficient shoot-regenerating root explant system permitted us to study the genetics of this trait and to locate the genes involved, using a set of morphological markers defining all 12 tomato chromosomes. Depending on the tomato genotype, mono, -di- or trigenic ratios were observed. It is concluded that a dominant L. peruvianum allele at a locus (Rg-1) near the middle of chromosome 3 determines efficient shoot regeneration on root explants in tomato in combination with dominant alleles at one or two other loci of either L. peruvianum or L. esculentum origin. The map location of the Rg-1 locus was refined further using a number of chromosome-3-specific RFLPs. The addition of new classical and RFLP linkage data to existing literature data and subsequent processing resulted in a revised and integrated map of tomato chromosome 3. From a morphological and physiological analysis of genotypes differing in Rg phenotype, it is concluded that the genetic component associated with regeneration determines the maintenance of morphogenetic competence and not the sensitivity to hormones.

The aim of the study was to investigate the effect of the boiling process on the content of ascorbigen, indole-3-carbinol, indole-3-acetonitrile, and 3,3'-diindolylmethane in fermented cabbage. The cabbage was boiled for 5 to 60 min. Boiling resulted in a decrease of the total content of the compounds analysed. The changes were mainly caused by leaching of ascorbigen predominating in cabbage into cooking water and by its thermal hydrolysis. Ascorbigen losses resulting from thermal hydrolysis accounted for 30% after 10 min of boiling and for 90% after 60 min of boiling. One of the ascorbigen breakdown products was indole 3 carbinol; the decrease in ascorbigen content was accompanied by a drastic increase in the content of 3,3'-diindolylmethane, a condensation product of indole-3-carbinol. After 40 and 50 min of boiling, the total content of 3,3'-diindolylmethane in cabbage and cooking water was approximately 0.2 micromol/100 g and was 6-fold higher than that in uncooked cabbage. 3,3'-Diindolylmethane synthesis proceeded within the plant tissue. After 10 min of boiling, the content of free indole-3-carbinol and indole-3-acetonitrile stabilized at the level of about 80% as compared to the uncooked cabbage.

Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

The intake of several bioactive components in food products has been associated with lower incidence in various ageing diseases. A group of compounds that is receiving a lot of attention in this respect is the group of natural antioxidants that are present in many food products of plant origin. It is important to know what the effects of processing steps are on the level and activity of these compounds in processed foods. With this information, more accurate figures can be given for epidemiological work. Also product development can be directed to consumer foods with an optimal content and activity of natural antioxidants. Results from studies on the effects of processing on the level and activity of antioxidants in apple and tea are presented as examples of such an approach. A combination of using analytical techniques for the determination of the level of bioactive compounds and in vitro techniques for the determination of the biological activity of the final food product and the intermediate products has been applied. Both decreases as well as increases in the level and activity of antioxidants have been observed depending on the processing conditions. A comparison is made between the measured antioxidant activity of a food product and the predicted activity based on a model taking into account the level and activity of the individual components as determined in the analytical assays. The correlation between these figures is quite good for tea, but for apple juice about 80% of the activity cannot be explained by the measured antioxidants. Matrix effects or the presence of yet unidentified antioxidants in the product can be responsible for this discrepancy.

PurposeThe purpose of the paper is to present an integrated methodology for identifying effective economic incentives to enhance quality performance by mango producers in Costa Rica.Design/methodology/approachThe study analyses the relationship between intrinsic product quality attributes and socio‐economic characteristics of mango producers in the Central Pacific zone of Costa Rica. Data are derived from a representative sample of 35 mango producers. A mango quality index for local and export market outlet is constructed and quality performance is subsequently related to farm‐household characteristics and contractual delivery parameters. Categorical regression methods are used to identify the relationships between farm‐household characteristics, production system features, marketing relationships and quality attributes weighted by consumers' preferences.FindingsKey attributes of the quality index – related to dimensions of ripeness, appearance and variability – appear to be strongly related to farm‐household characteristics like the producers' age and experience, input use intensity and family labour availability. Preferences for certain contractual regimes and marketing arrangements give rise to differentiation in quality performance. Long‐term delivery relationships and non‐price attributes appear as key factors for quality improvement in mango.Research limitation/implicationsAlthough the study is based on a modest sample, the significant relationships between the constructs in the model are found to be sufficiently robust.Originality/valueThe research approach enables the estimation of a model where quality performance is related to technical and institutional aspects related to the organisation of mango delivery chain.

Glucosinolates and their breakdown products have been recognized for their effects on plant defense, human health, flavor and taste of cruciferous vegetables. Despite this importance, little is known about the regulation of the biosynthesis and degradation in Brassica rapa. Here, the identification of quantitative trait loci (QTL) for glucosinolate accumulation in B. rapa leaves in two novel segregating double haploid (DH) populations is reported: DH38, derived from a cross between yellow sarson R500 and pak choi variety HK Naibaicai; and DH30, from a cross between yellow sarson R500 and Kairyou Hakata, a Japanese vegetable turnip variety. An integrated map of 1068 cM with 10 linkage groups, assigned to the international agreed nomenclature, is developed based on the two individual DH maps with the common parent using amplified fragment length polymorphism (AFLP) and single sequence repeat (SSR) markers. Eight different glucosinolate compounds were detected in parents and F(1)s of the DH populations and found to segregate quantitatively in the DH populations. QTL analysis identified 16 loci controlling aliphatic glucosinolate accumulation, three loci controlling total indolic glucosinolate concentration and three loci regulating aromatic glucosinolate concentrations. Both comparative genomic analyses based on Arabidopsis-Brassica rapa synteny and mapping of candidate orthologous genes in B. rapa allowed the selection of genes involved in the glucosinolate biosynthesis pathway that may account for the identified QTL.

Thermal degradation of individual glucosinolates within the plant matrix was studied. Red cabbage samples were heated at different temperatures for various times. To rule out the influence of enzymatic breakdown and to focus entirely on the thermal degradation of glucosinolates, myrosinase was inactivated prior to the thermal treatments. All identified glucosinolates degradation when heated at temperatures above 100 °C. The indole glucosinolates 4-hydroxy-glucobrassicin and 4-methoxyglucobrassicin showed the highest degree of showed degradation, even at temperatures below 100 °C. Kinetic parameters have been estimated for the degradation that could be described by first-order kinetics. At temperatures below 110 °C indole glucosinolates have a significant higher degradation rate constant as compared to aliphatic glucosinolates. The breakdown of 4-hydroxyglucobrassicin seems to consist of two parallel reaction pathways. Based on the proposed degradation kinetics and the estimated parameters, the degree of thermal degradation of all individual glucosinolates at standardized heating conditions (blanching, cooking and canning) was simulated. Glucosinolates are expected to be not very susceptible to thermal degradation during blanching conditions. Cooking will cause more thermal degradation to indole glucosinolates (38%) as compared to aliphatic glucosinolates (8%). Canning, the most severe heat treatment, will result in significant thermal degradation (73%) of the total amount of glucosinolates.

Epidemiological studies on the relation between fruit and vegetable intake and chronic diseases show variable results. In many studies a small protective effect is found for fruit and vegetable intake and the risk for cardiovascular diseases and cancers. In other studies these effects could not be found in a statistically significant way. Experimental animal and mechanistic studies with cell lines or in humans show often clear protective effects of many phytochemicals like e.g. glucosinolates, flavonoids and carotenoids. In this paper the effect of variability in the food production chain on the results of epidemiological studies as predicted by probabilistic simulation studies is presented. Even if a very strong protective effect of a phytochemical is assumed, this variability will lead to only very small, non-significant, protective effects to be found in epidemiological studies. The effect of different scenarios to improve human health has been investigated. Increasing the fruit and vegetable consumption will produce far less benefits when compared with a scenario of increasing the level of phytochemicals and reducing the variability in its content.

The aim of this study was to investigate the chemoprotective effects of Brussels sprouts juice towards benzo[a]pyrene (B(a)P)-induced DNA damage in the single-cell gel electrophoresis (SCGE)/Hep G2 test system. This assay combines the advantages of the SCGE assay with that of the use of human-derived cells possessing inducible phase I and phase 11 enzymes. Co-treatment of Hep G2 cells with small amounts of Brussels sprouts juice (0.25-2.0 mul/ml) and B(a)P reduced the genotoxic effect of the latter in a dose-dependent manner. Contrary to the results with the crude juice, unexpected synergistic effects were observed with allyl isothiocyanate (AITC, 1.0-6.0 muM), a breakdown product of sinigrin, which is the most abundant glucosinolate in Brussels sprouts. Although these concentrations of AITC did not cause DNA damage per se, at higher concentrations (greater than or equal to 25 muM), the compound caused a pronounced dose-dependent DNA damage by itself. Mechanistic studies showed that Brussels sprouts juice causes induction of activities of ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) at dose levels which were protective towards B(a)P. In combined treatment experiments with (+/-)-anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE, 5.0 muM), the main genotoxic metabolite of B(a)P, and Brussels sprouts juice, only weak protection was found indicating that the mechanism of chemoprotection of Brussels sprouts is not mediated through inactivation of this metabolite. In conclusion, our findings show that Brussels sprouts are highly protective against B(a)P-induced DNA damage in human-derived cells. (C) 2002 Elsevier Science Ltd. All rights reserved.