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The present pilot study investigated the impact of debranning fractions and debranned kernels, used as ingredient, on phenolic acids (PAs) and total phenolic compounds content of pasta. In addition, the bioavailability of PAs in humans following the intake of pasta was investigated. Three different durum wheat products were tested: i) a pasta sample produced by enriching semolina with selected debranning fractions, obtained by sequential debranning; ii) a pasta sample produced by debranned kernels previously whole milled; iii) a pasta sample from standard semolina, considered as control. Results show that the level of phenolic compounds increases significantly when debranned products are used for pasta-making. Preliminary data regarding the bioavailability of phenolic compounds show that PAs bound to the dietary fibre complex of cereals are poorly absorbed but they can be further metabolized by gut microbiota. On the whole, the consumption of pasta with high content of phenolic compounds increases their bioavailability in absolute terms. Therefore, this approach proved to be useful for improving nutritional quality of cereal-based foods.

Introduction: The dietary guidelines recommend increasing wholegrain (WG) cereal intake, which is still far lower from recommendations. One of the main reasons for such low consumption is the prejudice of the technological and sensory properties, due to the presence of bran. Some solutions have been proposed to favour the consumption of less refined foods and among them debranning process appears a valuable toll to increase the hygienic-sanitary quality of cereal-based foods. However, to our knowledge no studies investigated the effects of the use of durum wheat debranning products in pasta-making on the content of bioactive compounds and on their bioavailability. Objectives: The present pilot study investigated the impact of bran fractions and debranned kernels, used as ingredient, on the content of the main bioactive compounds in pasta. In addition, the bioavailability of phenolic acids (PAs) in humans following the intake of pasta was investigated. Methods: Three different durum wheat products were tested: i) a pasta sample produced by enriching semolina with selected bran fractions, obtained by sequential debranning; ii) a pasta sample produced by debranned kernels previously whole milled; iii) a pasta sample from standard semolina, considered as control. Samples were analysed for their PAs content, total phenolic compounds, yellow coloured pigments and total dietary fibre. For the pilot study regarding to the bioavailability of phenolic acids (PAs), so far three subjects have been recruited, consuming 100 g of pasta test following a randomized design. Results: Overall, the level of bioactive compounds increases significantly when debranned kernels or bran fractions are used in pasta-making. Preliminary results show that the consumption of pasta containing debranned kernels or bran fractions increases the bioavailability of phenolic compounds in absolute terms, even if they are poorly absorbed. However, PAs bound to the dietary fibre complex of cereals can be further metabolized by gut microbiota. Conclusions: Based on current results, debranning process proved to be useful for improving nutritional quality of cereal-based foods. Further studies with larger sample size should be performed to confirm the present results.

BACKGROUND: The identification of novel plant-based functional foods or nutraceutical ingredients that possess bioactive properties with antioxidant function has recently become important to the food, nutraceutical and cosmetic industries. This study evaluates the polyphenolic composition, identifies bioactive compounds and assays the total antioxidant capacity of Prunus mahaleb L. fruits collected from different populations and sampling years in the countryside around Bari (Apulia Region, Italy). RESULTS: We identified nine polyphenolic compounds including major anthocyanins, coumaric acid derivatives and flavonols from P. mahaleb fruits. The anthocyanin content (in some populations > 500 mg/100 g fresh weight; FW) in the fruit was comparable to that reported for so-called superfruits such as bilberries, chokeberries and blackcurrants. Coumaric acid derivatives comprised a large portion of the total polyphenolic content in the P. mahaleb fruits. Antioxidant activities, assessed using oxygen radical absorbance capacity (ORAC) and Trolox equivalent antioxidant capacity (TEAC) assays, measured up to 15 and 4.5 mmol/100 g FW, respectively. CONCLUSION: Our findings suggest that mahaleb fruit (currently not consumed fresh or used in other ways) could serve as a source of bioactive compounds and therefore find interest from the functional food and nutraceutical industries, as a natural food colorant and antioxidant ingredient in the formulation of functional foods.

Resveratrol, a plant phenolic compound, is found in grapes and red wine, but is not widely distributed in other common food sources. The pathway for resveratrol biosynthesis is well characterized. Metabolic engineering of this compound has been achieved in tomato plants (Lycopersicon esculentum Mill.) in order to improve their nutritional value. Tomato plants synthesizing resveratrol were obtained via the heterologous expression of a grape (Vitis vinifera L.) cDNA encoding for the enzyme stilbene synthase (StSy), under the control of the fruit-specific promoter TomLoxB or the constitutive CaMV 35S promoter. The resulting 35S plants accumulate resveratrol in all the tissues, but in the highest amount in the fruits. While, as expected, LoxS transgenic plants only accumulate it in the fruits, in particular in the skin of the mature fruits. Quantitative analyses carried out on LoxS fruits were compared with those of 35S tomato lines. The LoxS fruits contained levels of trans -resveratrol that were 20-fold lower than those reported for the 35S line. The total antioxidant capability, ascorbate and gluthatione contents were also evaluated. A significant increase in all these antioxidant paramenters was found in the LoxS and 35S lines. These results could explain the higher capability that extract from transgenic fruits have to counteract the pro-inflammatory effects of phorbol ester in monocyte- macrophages via the inhibition of induced cyclo-oxygenase-2 enzyme.

Tomato tissues were transformed with a grape cDNA encoding the enzyme stilbene synthase transcriptionally regulated by TomLoxB, a tomato fruit specific promoter. The modified plants LoxS, accumulated new products, absent in the wild-type plants. These were identified as trans-resveratrol and trans-piceid. The accumulation of these metabolites was monitored in the fruit and in particular in the skin and the flesh of the mature fruit. The quantitative analyses carried out on LoxS plants were compared with those of tomato line constitutively expressing the grape cDNA (35SS). LoxS plants showed 20 times lower accumulation of the trans-resveratrol than 35SS line. In order to estimate the effects of the new biosynthetic pathways, chlorogenic acid, naringenin, and flavonols were quantified. The results obtained showed an increase in the synthesis of chlorogenic acid, naringenin and kaempferol in transgenic fruit. The total antioxidant capability and ascorbate content increased proportionally to the resveratrol synthesised. These results could explain the higher capability of transgenic fruits to inhibit the phorbole ester induced cyclooxygenase-2 enzyme, in monocyte-macrophage cultures.

Tomato fruit contains only small amounts of flavonoids, and do not produce any stilbenes. With the aim of generating plants and fruits with increased antioxidant capacity and a wider range of potential health benefits, the tomato flavonoid route was modified through the over-expression of the grape stilbene synthase cDNA. The expression of the StS gene in tomato tissues caused the synthesis of new compounds, not present in either wild type or vector transformed plants, which were identified as trans-resveratrol and trans-resveratrol-glucopyranoside and which have a different tissue specificity, both depending on the promoter used and on the amount of precursors present in the tissues. Since the free radical scavenging capabilities of resveratrol are well known, we wanted to analyse whether its presence in tomato plants and fruit affected the level and/or the metabolism of other antioxidants normally present in tomato. The results here reported indicate that the synthesis of resveratrol affects certain metabolic routes related to primary antioxidants in different ways, according to the levels of resveratrol produced in the tissue.

There is a growing interest in producing food plants with increased amounts of antioxidants because of their potential health benefits. In particular polyphenol, secondary metabolites, such as flavonoids and stilbenes, have a great antioxidant activity, important both for plant physiology and human nutrition. With the aim of generating plants and fruits with increased antioxidant capacity and a wider range of potential health benefits, the tomato flavonoid route was modified through the over-expression of the grape stilbene synthase cDNA under constitutive promoter and a tissue specific, TomLoxB, promoter. The expression of the StS gene in tomato tissues caused the synthesis of new compounds, identified as trans-resveratrol and trans-resveratrol-glucopyranoside which have a different tissue specificity, both depending on the promoter used and on the amount of precursors present in different tissues. In order to verify the metabolic impairment, the amounts of soluble phenolics (i.e. chlorogenic acid) flavonoids (i.e. naringenin) and flavonols (i.e. rutin, and quercetin), in both transgenic and wild type fruits tissues at different stages of maturity, were compared. The results indicate that the stilbenes and the flavonoids found in transgenic plants are present as conjugates. Since the free radical scavenging capabilities of resveratrol are well known, we wanted to analyse whether its presence in tomato fruit affected the level and/or the metabolism of other antioxidants naturally present in tomato. The synthesis of resveratrol affects the other antioxidants in different ways, in particular ascorbate was increased in the transformed tissues. The alteration of ascorbate seem to be proportional to the amount of the resveratrol accumulated in the different tissues. Our results support the view-point that cross-talk between endogenous and introduced pathways is much more complex that the simple competition of enzymes for the same substrates.