Marco Paini

Combined effect of starter culture and temperature on phenolic compounds during fermentation of Taggiasca black olives

The influence of two operative parameters on the fermentation process of table olives from Taggiasca cultivar were investigated. Laboratory scale fermentations were performed using Lactobacillus plantarum as the only starter and in combination with Saccharomyces cerevisiae at three different temperatures (23, 30 and 37°C). Control tests used for each trial were fermented only by indigenous microflora. pH and phenolic compounds were monitored in the brine and olive flesh during the fermentation. Higher temperatures (37°C) enhanced notably the release of phenolic compounds in the brine. High performance liquid chromatography (HPLC) analysis of brines evidenced the complete hydrolysis of oleuropein after 100 days of fermentation at 37°C for all treatments. The antioxidant power of the extracts was linearly correlated to their polyphenol contents. The results confirmed the efficiency of treatments compared with the control tests for debittering process of table black olives. Phenolic compounds in the brines can be then extracted and used in food, cosmetic and pharmaceutical industries.

Chitosan/dextran multilayer microcapsules for polyphenol co-delivery

Polysaccharide-based nanostructured polymeric microcapsules were fabricated by the electrostatic layer-by-layer self-assembly technique and used to encapsulate mixtures of four different polyphenols in order to achieve their controlled release. The real-time fabrication of the dextran/chitosan multilayer was monitored by quartz crystal microbalance with dissipation monitoring, and the morphology of the nanostructured polymeric capsules was characterized by scanning electron microscopy. The polyphenol encapsulation was obtained by reversible permeability variation of the capsule shell in ethanol:water mixtures. The loading efficiency in different water:ethanol mixtures and the release rate in acidic conditions were characterized by UV spectroscopy and HPLC. The higher loading efficiency was obtained with an ethanol:water 35:65 phenolic solution, equal to 42.0±0.6%, with a total release of 11.5±0.7 mg of total polyphenols per 11.3 μL of microcapsules after 240 min of incubation in acidic environment. The results suggest that polysaccharide-based capsules can be successfully used to encapsulate and release low water-soluble molecules, such as polyphenols.

An efficient liposome based method for antioxidants encapsulation

Apigenin is an antioxidant that has shown a preventive activity against different cancer and cardiovascular disorders. In this study, we encapsulate apigenin with liposome to tackle the issue of its poor bioavailability and low stability. Apigenin loaded liposomes are fabricated with food-grade rapeseed lecithin in an aqueous medium in absence of any organic solvent. The liposome particle characteristics, such as particle size and polydispersity are optimised by tuning ultrasonic processing parameters. In addition, to measure the liposome encapsulation efficiency accurately, we establish a unique high-performance liquid chromatography technique in which an alkaline buffer mobile phase is used to prevent apigenin precipitation in the column;. salt is added to separate lipid particles from the aqeuous phase. Our results demonstrate that apigenin encapsulation efficiency is nearly 98% that is remarkably higher than any other reported value for encapsulation of this compound. In addition, the average particle size of these liposomes is 158.9 ± 6.1 nm that is suitable for the formulation of many food products, such as fortified fruit juice. The encapsulation method developed in this study, therefore have a high potential for the production of innovative, functional foods or nutraceutical products.

High-Pressure and Temperature Extraction of Phenolic Compounds from Corn Silage

Corn silage refers to stalks, leaves and cobs of maize plants that remain in fields after the corn harvest. Commonly it is used as a cattle feed, but recently it has been more often used together with cattle manure in biofuel production in anaerobic co-digestion. In this work high-pressure and temperature extraction of phenolic compounds from corn silage was performed. Process parameters (temperature, T = 90 – 180 °C; extraction time, t = 40 – 120 min; liquid – solid ratio, 10 – 20 mL/g; and solvent concentration (10 – 90 % aqueous ethanol, v/v) were studied. Box-Bhenken design was used in order to obtain the maximal extractability of phenolic compounds (namely total phenolic compoundsTPC and total extractible proanthocyanidins - TPA) and the maximal antiradical power (ARP) of obtained extracts. Experimental results of TPC, TPA, and ARP of corn silage extracts were in the range from 10.01 – 72.43 mgGallicAcid Equivalent/gdrybiomass, 0.27 – 3.21 mg/gdrybiomass and 1.25 – 16.76 mgDPPH/mLextract, respectively. Statistical results confirmed that temperature was the most significant factor affecting the observed responses (p < 0.05). Optimal extraction conditions for TPA and ARP were achieved at 180 °C, 120 min using 65 % ethanol and L/S ratio 10 while optimal conditions for TPC were achieved at 180 °C, 120 min using 10 % ethanol and L/S ratio 20. The results of this study evidenced that extracts from corn silage can be a good source of antioxidant compounds which can be used for production of food, cosmetic and pharmaceutical products.

Effect of Encapsulating Agent on Physical-chemical Characteristics of Olive Pomace Polyphenols-rich Extracts

During the last years, olive industry wastes are considered as a potential source of extracts with antioxidant properties rich in polyphenols. The recovery of these added-value compounds can be interesting both for their beneficial properties and from an environmental point of view and several studies have been performed for the optimization and characterization of the phenolic compounds present in olive pomace liquid extracts. However, dried forms of natural extracts are associated with several advantages over liquid forms, such as limited storage costs, higher concentration and stability of target compounds. Spray drying is one of the most common techniques for the transformation of a liquid extract, or food formulation, into dried powder, due to low operative costs respect to other methods, and high flexibility, related to the large number of operative parameters that can be optimized, such as coating agent type and concentration, inlet temperature, feed flow and aspiration rate. In this study, an ethanolic extract rich in phenolic compounds from olive pomace (Taggiasca cultivar) was obtained by high pressure and temperature extraction and spray dried with different ratios of gum arabic and maltodextrin as coating agents (0:100, 20:80, 40:60, 60:40, 80:20 and 100:0 % w/w). The total amount of coating agent was maintained constant and equal to 10 % w/v (100 g/L). Inlet temperature, feed flow and aspiration rate were 160 °C, 5 mL/min and 30 m3/h, respectively. For all products, moisture content, water solubility index, total polyphenol content, antiradical power and microencapsulation yield were determined. The results of this study show that the coating agent and process conditions led to the production of microencapsulated powders with improved water dissolution rate and a minimal loss in phenolics during the drying phase. The obtained microparticles, due to their high content in bioactive compounds and ease of handling, can have potential industrial applications as functional components for foods or nutraceuticals purposes.