Paola Pittia

Effect of Fermentation and Drying on Procyanidins, Antiradical Activity and Reducing Properties of Cocoa Beans

This work was aimed to determine the effect of fermentation and drying on the content and profile of procyanidins (from monomers P1 to polymers P10) as well as on the antiradical and scavenging properties of cocoa beans. To this purpose, three experiments were carried out: a traditional fermentation process followed by air drying and two pilot-scale fermentation processes by either natural microbiota or starter followed by sun drying. Procyanidins were evaluated by HPLC analysis, while the total polyphenol index (TPI), the antiradical activity as well as the reducing power were determined by means of the reaction with the Folin–Ciocalteu reagent, the decolorization assays of the ABTS radical (TEAC) and the Ferric Reducing Antioxidant Power (FRAP) methods, respectively. Both the traditional and pilot-scale processes resulted to affect the profile and content of the procyanidins fractions as well as the antiradical and reducing power functionality. Drying caused a severe reduction of compounds and thus resulted to be the critical step for the loss of procyanidins and monomers in particular. The indices of functionality generally showed a decreasing trend as a consequence of processing, and their evolution was similar to that observed in procyanidins content. To study the relationship between the individual procyanidins and the antioxidant activity expressed as TEAC, FRAP and TPI, the data set were processed by modified partial least squares regression. The obtained models presented a good predictive ability. Normalised regression coefficients showed that the relative contribution of each single class of compounds to total antioxidant activity resulted as follows: P1 > P2 > P3 > P4 > P6 > P8 > P5 > P7 > P9 >> P10.

Shelf-life extension of fresh-like ready-to-use pear cubes

Minimally processed fruit and vegetables are generally more perishable than the original raw materials due to the injury stresses during preparation that greatly increase tissue respiration and lead to deterioration through various biochemical pathways. In this paper, the effects of low intensity blanching treatments on enzymatic and microbiological stability on the fresh-like quality of ready-to- use pear cubes has been evaluated. Blanching treatments as well as packaging were carried out both in aseptic and in non-aseptic conditions. The combination of low intensity blanching with superficial enzymatic treatments has been carried out. The results confirm that the combination of a mild heat treatment (3 min at 95 °C) under aseptic conditions is enough to enhance the stability of this minimally processed product with an acceptable reduction in the texture. The superficial treatment with lysozyme did not result in an improvement in the stability of the blanched pear cubes during storage under refrigerated conditions. # 1999 Society of Chemical Industry

Gold nanoparticles-peptide based gas sensor arrays for the detection of food aromas.

A gas sensor array based on peptide modified gold nanoparticles deposited onto 20MHz quartz crystal microbalances has been realized. Glutathione and its constituting aminoacids and dipeptides have been used as ligands. A great increase in sensitivity (2 orders of magnitude) was achieved using gold nanoparticles versus monolayer modified QCMs. The sensors have been characterised in terms of sensitivity for hexane, water, trimethylammine and ethanol. Highest sensitivity was found for water. The ability to discriminate typical food aromas as cis-3-hexenol, isopentylacetate, ethylacetate, and terpinen-4-ol dissolved in different solvents was studied using a gas sensor array constituted by gold nanoparticles modified with the glutathione peptides, thioglycolic acid and an heptapeptide. The array was found able to discriminate the food aromas, the response being dependent on the polarity of the solvent used. Tests on real olive oil samples gave a satisfactory separation among samples having defects versus non defected samples demonstrating that this approach has high potential for the development of gas sensor arrays to be used in real samples.

Effect of Blanching in Water and Sugar Solutions on Texture and Microstructure of Sliced Carrots

Thermal processing of vegetables has pronounced effects on the cell structure, often negatively affecting the final textural properties of the product. In order to study the effect of thermal processing and the protective effect of sugars on the tissue, sliced carrots were subjected to blanching treatments under different time and temperature combinations both in water and in 4% sugar solutions made of trehalose or maltose. The influence of these process conditions on mass transfer, texture, and microstructure (Cryo-scanning electron microscopy) was thus investigated. The total mass loss of all the samples blanched in water was associated to their cook value (C(100)(18)) except for the overprocessed one (90 °C, 10 min) that showed a total mass change significantly lower due to water uptake. The use of trehalose and maltose in the blanching solution reduced the solute loss while increasing the water loss. Microstructural analysis of the differently blanched carrots showed detachments between adjacent cell walls as well as plasmolysis phenomena as the time and temperature of the thermal treatment were increased. A protective effect of both sugars on cell structures was observed mostly in the sample treated at 90 °C. At macroscopic level, textural changes upon blanching were observed by a penetration test. As blanching time was increased, samples processed at 75 °C showed a hardness increase, while those processed at 90 °C showed a hardness decrease. However, both trehalose and maltose did not exert significant effects on the textural properties of blanched carrots when compared with those blanched in water. Practical Application: The results of this study could offer interesting perspectives in the optimization of the heat treatments in order to preserve the quality of semi-finished processed vegetables. Furthermore, the microstructural analysis is nowadays an important investigation tool that could contribute to a deeper understanding of both the effects of processing and ingredients on the vegetable microstructure and its relationship with the changes occurring on the quality properties at macroscopic level.

Effect of Olive Oil Phenolic Compounds and Maltodextrins on the Physical Properties and Oxidative Stability of Olive Oil O/W Emulsions

The aim of this work was to study the physical properties and oxidative stability of model olive oil-in-water (o/w) emulsions stabilised by β-lactoglobulin (BLG), enriched with olive phenolic compounds, namely oleuropein, tyrosol and hydroxytyrosol, and added with maltodextrins (MD 7.5–9.9) in different concentrations to modify the viscosity of the continuous water phase. Emulsions were characterized for their viscosity, droplet size distribution, microstructure and interfacial protein coverage. The oxidative stability was monitored by means of hydroperoxides, hexanal and nonanal contents as indices of primary and secondary oxidation products, respectively. At high concentrations, MD increased significantly the viscosity of the emulsions; conversely, the addition of olive phenolic compounds did not show any significant effect on it. Both MD and phenolic compounds resulted to affect both the droplet size and the bigger to smaller particles ratio, with phenolic compounds generally improving the dispersion degree. A delay in the decomposition of hydroperoxides was observed as a consequence of MD addition, which also resulted to affect the efficiency of the phenolic compounds among the different systems. However, the highest protection towards oxidations was obtained when hydroxytyrosol was added. MD effect was related not only to the higher viscosity of the emulsions but also to complex interactions that occurred among the different components of the system.

Evaluation of Microstructural Properties of Coffee Beans by Synchrotron X-Ray Microtomography: A Methodological Approach

UNLABELLED Synchrotron radiation microtomography was used as a nondestructive imaging technique to investigate the microstructural properties of green and roasted coffee beans. After image acquisition, 2D images have been reconstructed and 3D images of the beans have been then obtained. Qualitative and quantitative analysis of the images allow to fully characterize the morphological and structural features of the coffee beans. Roasting causes meaningful changes in the microstructure of the coffee bean tissue with the development in the entire bean of a porous structure with pores of different shape and size depending on the zone of the bean and cracks occurring mainly in the more external regions and between parenchyma and mucilage. The highly contrasted X-ray images have been analyzed to determine the pore size and its distribution in different regions of the coffee beans by selecting Volume-of-Interest (VoI). The use of phase-contrast hard X-rays imaging techniques represents an interesting tool of investigation of the internal structure, morphology, as well as the quality of whole coffee beans. Moreover, the high potentiality of 3D X-ray imaging and the approach used in this study could be applied in understanding the effects of roasting process conditions on the evolution of microstructural properties of the bean that may affect the stability as well the grinding and brewing performances. PRACTICAL APPLICATION Synchrotron radiation microtomography is an elegant nondestructive imaging technique to investigate the microstructural properties of porous cellular matrices like the green and roasted coffee beans. The quantitative analysis of the resulting 2D and 3D images allows a more comprehensive and objective characterization of the sample under investigation as a whole or of extracted Volumes-of-Interest in the bean. This imaging technique could have a major role in understanding the effects of roasting process conditions on the microstructural properties of the bean.

Role of olive oil phenolics in physical properties and stability of mayonnaise-like emulsions

The effect of olive oil phenolic content and pattern on the physical properties and stability of olive oil mayonnaise-like emulsions has been investigated. Mayonnaises were formulated with either naturally phenolic-rich extra virgin olive oils or purified olive oil artificially enriched with a phenolic-rich olive extract and pure oleuropein. Mayonnaises were characterized by droplet size distribution, microstructure, textural properties and flow behaviour. The addition of phenolic extracts significantly affected the dispersion degree of the corresponding mayonnaise-like emulsions, their microstructure and physical stability especially in the systems prepared with purified olive oil treated with pure oleuropein and the highest olive phenolic extract concentration. The viscosity and back-extrusion analyses evidenced that the systems characterized by a relatively high content of phenolics, either natural or by addition, presented lower yield stress and viscosity indices and were easier to deform and to break. This study confirms the main role of olive phenolic compounds, and in particular that of oleuropein, in the dispersion state, and physical properties of emulsions with main effects on their quality and stability.

Tailoring gas sensor arrays via the design of short peptides sequences as binding elements

A semi-combinatorial virtual approach was used to prepare peptide-based gas sensors with binding properties towards five different chemical classes (alcohols, aldehydes, esters, hydrocarbons and ketones). Molecular docking simulations were conducted for a complete tripeptide library (8000 elements) versus 58 volatile compounds belonging to those five chemical classes. By maximizing the differences between chemical classes, a subset of 120 tripeptides was extracted and used as scaffolds for generating a combinatorial library of 7912 tetrapeptides. This library was processed in an analogous way to the former. Five tetrapeptides (IHRI, KSDS, LGFD, TGKF and WHVS) were chosen depending on their virtual affinity and cross-reactivity for the experimental step. The five peptides were covalently bound to gold nanoparticles by adding a terminal cysteine to each tetrapeptide and deposited onto 20MHz quartz crystal microbalances to construct the gas sensors. The behavior of peptides after this chemical modification was simulated at the pH range used in the immobilization step. ΔF signals analyzed by principal component analysis matched the virtually screened data. The array was able to clearly discriminate the 13 volatile compounds tested based on their hydrophobicity and hydrophilicity molecules as well as the molecular weight.

Safety by Control of Water Activity: Drying, Smoking, and Salt or Sugar Addition

Abstract Salting, drying, smoking are traditional preservation techniques. The “water activity” (aw) concept and its role on the inhibition of the main degradation biochemical and chemical reactions and microbial growth in foods have defined the change from traditional, empirically developed to science-based processes. The understanding of the water–food matrix interactions, the role of humectants and the effect of the “water freedom” in the control of microbial growth, the inhibition of enzymatic activity and the modulation of the chemical reaction rates have given the scientific sound to the ancient use of salt, sugars, and the natural water removal by drying and smoking for preservation purposes. In this chapter, salting, smoking, drying will be presented as referred to their impact on the aw of the traditional food products, their quality and safety. The more recent approach in using the aw parameter in combination with other technological actions or hurdles (hurdle technology) will be also presented.

Skill development in food professionals : a European study

Abstract The food sector is the largest employer in the European Union, yet it ranks low in innovation and few educated young people pursue food careers. Updating both the skills and the image of food science and technology professionals (FSTs) first requires understanding the current situation. This work compares the view of currently employed FSTs (3,007) with that of food science and technology (FST) employers (602) regarding skills and when and where they should be developed. European FSTs responded to a web-based survey in 2011 and 2012, and FST employers responded to an e-mail-based survey and/or attended brainstorming workshops from 2009 to 2012. Soft skills, especially those related with communication, were the best evaluated by both groups, whereas technical non-food skills were in the lowest positions. FSTs were judged qualified by their employers in some food skills (food safety and quality, product development, production), while others (engineering maintenance, consumer and nutritional sciences, environmental issues) were more poorly evaluated. In general, FSTs believe themselves to be well qualified by higher education programs, and most of them do not continue training once they are working, with the notable exception of those that achieve positions of high responsibility. However, employers appeared to disagree, recommending that education and training in soft, food and technical skills continue throughout working life. Additionally, they recommended more frequent reinforcement of soft than of food or technical skills. A competitive food sector requires FSTs of the highest quality, and understanding the view of FSTs and their employees can contribute to improved training and thus benefit the European food sector.