Study of the effects of pasteurization and selected microbial starters on functional traits of fermented table olives.

Table olives are one of the most known fruit consumed as fermented food, being a fundamental component of the Mediterranean diet. Their production and consumption continue to increase globally and represent an important economic source for the producing countries. One of the most stimulating challenges for the future is the modernization of olive fermentation process. Besides the demand for more reproducible and safer production methods that could be able to reduce product losses and potential risks, producers and consumers are increasingly attracted by the final product characteristics and properties on human health. In this study, the contribution of microbial starters to table olives was fully described in terms of specific enzymatic and microbiological profiles, nutrient components, fermentation-derived compounds, and content of bioactive compounds. The use of microbial starters from different sources was tested considering their technological features and potential ability to improve the functional traits of fermented black table olives. For each fermentation assay, the effects of controlled temperature (kept at 20 °C constantly) versus not controlled environmental conditions (oscillating between 7 and 17 °C), as well as the consequences of the pasteurization treatment were tested on the final products. Starter-driven fermentation strategies seemed to increase both total phenolic content and total antioxidant activity. Herein, among all the tested microbial starters, we provide data indicating that two bacterial strains (Leuconostoc mesenteroides KT 5-1 and Lactiplantibacillus plantarum BC T3-35), and two yeast strains (Saccharomyces cerevisiae 10A and Debaryomyces hansenii A15-44) were the better ones related to enzyme activities, total phenolic content and antioxidant activity. We also demonstrated that the fermentation of black table olives under not controlled environmental temperature conditions was more promising than the controlled level of 20 °C constantly in terms of technological and functional properties considered in this study. Moreover, we confirmed that the pasteurization process had a role in enhancing the levels of antioxidant compounds.

Whole Grape Pomace Flour as Nutritive Ingredient for Enriched Durum Wheat Pasta with Bioactive Potential.

In this study, grape pomace is used as an ingredient to fortify pasta. The grape pomace phenolic component is highly accessible and available for metabolization in the human gut. Hence, grape pomace can be exploited as a source of polyphenols and fiber for sustainable and dietary beneficial food production. Analyses of soluble and bound phenols and volatile compounds in raw and cooked pasta were performed. In the uncooked pasta fortified with pomace, the content of soluble and bound phenolic molecules increased significantly. During the cooking process, the bound phenols were lost, while the soluble phenols doubled. The whole grape pomace flour as a pasta ingredient increased the fiber component by at least double, increased the soluble polyphenol component by at least 10 times, and doubled the isoprenoids (toco-chromanols and carotenoids) while maintaining the unaltered fatty acid content after cooking. In accordance with the polyphenol content, antioxidant activity resulted higher than that of the control pasta. Analysis of volatile compounds in fortified pasta, both uncooked and cooked, indicated an improvement in aromatic profile when compared to the control pasta. Our results show that durum wheat pasta fortified with whole pomace flour has bioactive potential for the reuse of food industry byproducts.

Liquid submerged fermentation by selected microbial strains for onion skins valorization and its effects on polyphenols.

Onion skins, actually recycled as organic fertilizers, could be used as a substrate in environmental-friendly bioprocesses to recover high-value bioactive compounds and food ingredients.In this work, a bioprospecting method was carried out including 94 bacterial and 45 yeast strains from several agri-food and environmental niches to verify their ability to grow on onion skins as unique nutrients source.Red and yellow onion skins were assessed by newly selected starter-driven liquid submerged fermentation assays mainly aimed at the release and modification of polyphenols through microbial activities. Fermented onion skins were also investigated as a inexpensive favourable source of microbial enzymes (amylases, proteases, lipases, esterases, cellulases, xylanases).In red onion skins, the treatment with Lactiplantibacillus plantarum TB 11-32 produced a slight increase of bioactive compounds in terms of total phenolics, whereas with the yeast strain Zygosaccharomyces mrakii CL 30 - 29 the quercetin aglycone content increased of about 25% of the initial raw material.In yellow onion skins inoculated, the highest content of phenolic compounds was detected with the yeast strain Saccharomyces cerevisiae En SC, while quercetin aglycone increased of about 60% of the initial raw material in presence of the bacterial strain L. plantarum C 180 - 34.In conclusion, the proposed microbial pre-treatment method can be a potential strategy to re-use onion skins as a fermentation substrate, and as a first step in the development of a biorefinery process to produce value-added products from onion by-products.

Drought and Heat Stress Impacts on Phenolic Acids Accumulation in Durum Wheat Cultivars.

Droughts and high temperatures are the main abiotic constraints hampering durum wheat production. This study investigated the accumulation of phenolic acids (PAs) in the wholemeal flour of six durum wheat cultivars under drought and heat stress. Phenolic acids were extracted from wholemeals and analysed through HPLC-DAD analysis. Ferulic acid was the most represented PA, varying from 390.1 to 785.6 µg/g dry matter across all cultivars and growth conditions, followed by sinapic acids, p-coumaric, vanillic, syringic, and p-hydroxybenzoic acids. Among the cultivars, Cirno had the highest PAs content, especially under severe drought conditions. Heat stress enhanced the accumulation of minor individual PAs, whereas severe drought increased ferulic acid and total PAs. Broad-sense heritability was low (0.23) for p-coumaric acid but ≥0.69 for all other components. Positive correlations occurred between PA content and grain morphology and between test weight and grain yield. Durum wheat genotypes with good yields and high accumulation of PAs across different growing conditions could be significant for durum wheat resilience and health-promoting value.

Strategies for Reuse of Skins Separated From Grape Pomace as Ingredient of Functional Beverages.

Wine grape pomace, the by-product of wine making, is a source of polyphenols, metals, and organic acids, and may be exploited for the production of functional beverages. Among red wines, Primitivo and Negramaro varieties possess an interesting amount of polyphenolic compounds and other chemicals. Consequently, study of the biological activity of Primitivo and Negramaro vinification by-products is of great interest as well as optimizing the extraction of its bioactive components. In order to stabilize the grape pomace, different methods of drying grape pomace were tested. After stabilization of the pomace, the grape skins were manually separated from the seeds and any woody parts. The chemical characterizations of acidified alcoholic (methanol/ethanol) and water extracts and either microwave-assisted or ultrasound-assisted extractions of separated grape skins were compared. Besides that, the in vitro antioxidant activity of wine pomace skin extracts was also investigated as Trolox equivalents antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC). Overall, the alcoholic extractions were found to be the most effective for recovering phenolic compounds, when compared with those in water. Ultrasound- and microwave-assisted extraction of pomace skin using acidified water allowed the highest TEAC value. Taking into account the water extraction result, in order to reuse grape pomace skins to produce a functional beverage, we utilized them in combination with black tea, karkadè (Hibiscus sabdariffa L.), or rooibos (Aspalathus linearis Burm.) to produce an infusion. The combination of grape skins and black tea showed the highest ratio of total phenol content to antioxidant activity. Moreover, skin isolated from pomace, with or without black tea infusions, were shown to have anti-inflammatory capacity in human cell culture. Our results raise the value of grape skin pomace as a rich source of bioactive compounds with antioxidant and anti-inflammatory activity and suggest its exploitation as an ingredient for functional beverages.

Jasmonates elicit different sets of stilbenes in Vitis vinifera cv. Negramaro cell cultures.

The plant phenol trans-resveratrol, which is mainly found in grape, displays a wide range of biological effects. A cell suspension culture was developed from calli of grape leaves of Vitis vinifera cv. Negramaro in order to study the bioproduction of resveratrol. The effects of a number of secondary plant metabolism elicitors, namely chitosan, methyl jasmonate, jasmonic acid, coronatine, and 12-oxo-phytodienoic acid, were tested on this cell suspension culture. The identification and quantification of stilbenes was achieved with high performance liquid chromatography, with both spectrophotometric and mass spectrometric detection. Of the tested elicitors, methyl jasmonate was the most effective in inducing the biosynthesis of approximately 4 mg g(-1) dry weight (about 60 mg L(-1)) of resveratrol. Conversely, 12-oxo-phytodienoic acid, jasmonic acid, and coronatine were able to trigger the synthesis of approximately 20 mg g(-1) dry weight (200-210 mg L(-1)) of viniferins. Taken together, our results show for the first time different modulatory effects of closely-related jasmonates on stilbene biosynthesis.

Effect of drying and co-matrix addition on the yield and quality of supercritical CO2 extracted pumpkin (Cucurbita moschata Duch.) oil.

In this work a process for obtaining high vitamin E and carotenoid yields by supercritical carbon dioxide (SC-CO2) extraction from pumpkin (Cucurbita moschata Duch.) is described. The results show that the use of a vacuum oven-dried [residual moisture (∼8%)] and milled (70 mesh sieve) pumpkin flesh matrix increased SC-CO2 extraction yields of total vitamin E and carotenoids of ∼12.0- and ∼8.5-fold, respectively, with respect to the use of a freeze-dried and milled flesh matrix. The addition of milled (35 mesh) pumpkin seeds as co-matrix (1:1, w/w) allowed a further ∼1.6-fold increase in carotenoid yield, besides to a valuable enrichment of the extracted oil in vitamin E (274 mg/100 g oil) and polyunsaturated fatty acids. These findings encourage further studies in order to scale up the process for possible industrial production of high quality bioactive ingredients from pumpkin useful in functional food or cosmeceutical formulation.

Antioxidant and anti-inflammatory properties of tomato fruits synthesizing different amounts of stilbenes.

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. The resulting LoxS transgenic plants accumulated trans-resveratrol and trans-piceid, in particular in the skin of the mature fruits. Quantitative analyses carried out on LoxS fruits were compared with those of a tomato line constitutively expressing the stsy gene (35SS). The LoxS fruits contained levels of trans-resveratrol that were 20-fold lower than those previously reported for the 35SS line. The total antioxidant capability and ascorbate content in transformed fruits were also evaluated, and a significant increase in both was found in the LoxS and 35SS lines. These results could explain the higher capability of transgenic fruits to counteract the pro-inflammatory effects of phorbol ester in monocyte-macrophages via the inhibition of induced cyclo-oxygenase-2 enzyme.

Antioxidant metabolite profiles in tomato fruit constitutively expressing the grapevine stilbene synthase gene.

Tomato (Lycopersicon esculentum Mill.) tissues were transformed with a grape (Vitis vinifera L.) stilbene synthase cDNA, transcriptionally regulated by the cauliflower mosaic virus (CaMV) 35S promoter. Transgenic plants accumulated new compounds, not present in either wild-type or vector-transformed plants. These were identified, by high-pressure liquid chromatography, as trans-resveratrol and trans-resveratrol-glucopyranoside. The amounts of trans-resveratrol and its piceid form were evaluated in the transgenic fruit. It was found that the content of the metabolite varied during fruit maturation to up to 53 microg/g fresh weight of total trans-resveratrol at the red stage of ripening. This metabolite accumulation was possibly dependent on a combination of sufficiently high levels of stilbene synthase and the availability of substrates. With the aim of verifing the metabolic impairment, the amounts of chlorogenic acid and naringenin in both transgenic and wild-type ripening fruit were compared and no dramatic variation in the synthesis profile of the two metabolites was noted. To our knowledge, no data are available on the assessment of the effects of the expression of the StSy gene on other antioxidant compounds present in tomato fruit. To establish whether the presence of a novel antioxidant molecule affected the redox regulation in transgenic tomato fruit cells, the effect of resveratrol accumulation on the naturally present antioxidant pool was analysed. We showed that, in transgenic fruit which accumulate trans-resveratrol, there is an increase in the levels of ascorbate and glutathione, the soluble antioxidants of primary metabolism, as well as in the total antioxidant activity. Conversely, the content of tocopherol and lycopene, which are membrane-located antioxidants, is not affected. Consistent with the increased antioxidant properties, the lipid peroxidation was lower in transformed than in wild-type fruit.