Maria Cristina Nicoli

Review of non-enzymatic browning and antioxidant capacity in processed foods ☆

Browning reactions represent an interesting research area for the implications in food technology, nutrition and health. The development of some non-enzymatic browning reactions, such as Maillard reaction, has been recently associated to the formation of compounds with strong antioxidant capacity. In this paper, the relation between colour changes due to non-enzymatic browning and the formation of compounds with antioxidant activity is discussed. Simple positive or complex correlation between colour and antioxidant properties can be found depending on composition and technological history of the product. Complex relations between these variables are generally obtained in multi-component and in formulated foods, where the simultaneous development of a number of reactions, interacting or prevailing Maillard reaction itself, can affect in opposite ways the overall antioxidant properties and colour of the product.

Influence of processing on the antioxidant properties of fruit and vegetables

Abstract Nutritional factors are widely considered to be critical for human health. Overwhelming evidence from epidemiological studies indicate that diets rich in fruit and vegetables are associated with a lower risk of several degenerative diseases. These results have created a new perspective concerning the potential of diet in preventing serious diseases in the future. However, the health-promoting capacity of fruit and vegetables strictly depends on their processing history. This aspect has been generally neglected or scarcely considered in present nutritional and epidemiological studies. Processing is expected to affect content, activity and bioavailability of bioactive compounds. The aim of this article, therefore, is to review the effects of processing on the antioxidant properties of foods by means of a multidisciplinary approach. It is believed that the implications of this challenging and rapidly advancing area may contribute to enhanced industrial competitiveness as well as consumer health and well-being.

Loss and/or formation of antioxidants during food processing and storage

It is well known that natural antioxidants contained in foods are significantly lost during processing. Nevertheless it was recently demonstrated that thermal treatments can induce the formation of compounds with new antioxidant properties. This is the case of the Maillard reaction products (MRPs) whose presence as well as their potential effects have been scarcely investigated. In the present work the loss of natural antioxidants in relation to processing and the formation of MRPs with antioxidant activity were studied in different food systems such as tomato derivatives and coffee. Results showed that, although the concentration of natural antioxidants was significantly reduced as a consequence of the thermal treatments, the overall antioxidant properties of the food products were maintained or even enhanced by the development of MRPs.

Antioxidant properties of tomato juice as affected by heating

The changes in the overall antioxidant properties of tomato juice samples and model solutions as a consequence of heat treatments were studied. The antioxidant properties were evaluated both through the measurement of the chain breaking and the oxygen scavenging activities. While a decrease in the antioxidant potential was found for short heat treatments, a recovery of these properties was measured by prolonging heating times. Results suggested that the initial reduction in the overall antioxidant activity can be attributed not only to the thermal degradation of naturally occurring antioxidants but also to the formation of early Maillard reaction products (MRP) with pro-oxidant properties. The gain in antioxidant activity coincided with the formation of brown MRP. © 1999 Society of Chemical Industry

Nanoemulsion-Based Delivery Systems for Polyunsaturated (ω-3) Oils: Formation Using a Spontaneous Emulsification Method

Nanoemulsion-based delivery systems are finding increasing utilization to encapsulate lipophilic bioactive components in food, personal care, cosmetic, and pharmaceutical applications. In this study, a spontaneous emulsification method was used to fabricate nanoemulsions from polyunsaturated (ω-3) oils, that is, fish oil. This low-energy method relies on formation of fine oil droplets when an oil/surfactant mixture is added to an aqueous solution. The influence of surfactant-to-oil ratio (SOR), oil composition (lemon oil and MCT), and cosolvent composition (glycerol, ethanol, propylene glycol, and water) on the formation and stability of the systems was determined. Optically transparent nanoemulsions could be formed by controlling SOR, oil composition, and aqueous phase composition. The spontaneous emulsification method therefore has considerable potential for fabricating nanoemulsion-based delivery systems for incorporating polyunsatured oils into clear food, personal care, and pharmaceutical products.

Microstructure and bioaccessibility of different carotenoid species as affected by high pressure homogenisation: a case study on differently coloured tomatoes.

The effect of high pressure homogenisation (HPH) on structure (Bostwick consistency, particle size distribution and microstructure) and carotenoid in vitro bioaccessibility of different tomato pulps was investigated. HPH decreased tomato particle size due to matrix disruption and increased product consistency, probably due to the formation of a fibre network. Homogenisation also resulted in a decrease of in vitro bioaccessibility of lycopene, ζ-carotene, and lutein. Such decrease was attributed to the structuring effect of HPH. An inverse relation between tomato consistency and carotenoid in vitro bioaccessibility was found. This dependency was affected by carotenoid species and its localisation within the matrix. It could be observed that one matrix (e.g. (homogenised) red tomato pulp) can contain carotenoids with a very low bioaccessibility (lycopene) as well as carotenoids with a very high bioaccessibility (lutein), indicating that carotenoid bioaccessibility is not solely dependent on the matrix.

Chain-breaking and oxygen scavenging properties of wine as affected by some technological procedures

Abstract The chain-breaking and the oxygen scavenging properties of red and white wines as a consequence of some technological procedures were evaluated. Phenols in white wine samples showed an antioxidant power similar to those found in red wine despite their lower concentration. The addition of sulphur dioxide to wine and to a simple model system simulating wine, did not affect the chain-breaking capacity of the samples but greatly enhanced their oxygen consumption activity. The progressive polymerisation of phenols upon ageing was associated with a decrease in the antioxidant properties of wine, whilst the development of non-enzymatic browning reactions, as occurs in the production of Marsala-type wines, resulted in a great increase in its chain-breaking activity. ©

Polyphenoloxidase and peroxidase activity in partially frozen systems with different physical properties

Abstract Enzyme catalysed reactions can occur at significant rates at low temperatures, thus exerting a major control on the quality of frozen foods. The temperature-concentration effect in partially frozen systems can make enzyme reactions controlled by diffusion and thus rate limited by viscosity according to the Stokes–Einstein relation. Polyphenoloxidase (PPO) activity in sucrose, glycerol and fructose water media and (POD) activity in fructose and glycerol water media, were assayed spectrophotometrically from 20°C to −30°C. The media have at equal sub-freezing temperature marked differences in viscosities and others physical properties. For both enzymes, the activity data showed similar dependence on temperature and, above freezing, on the concentration of the media. A relation with the viscosity of the media at equal sub-freezing temperature was not evident. POD activity showed a “break” between −10°C and −20°C, suggesting a reversible conformational change. The temperature dependence of PPO rate constants were well described by both the Williams–Landel–Ferry ( r 2 =0.998) and the Arrhenius ( r 2=0.985) models. A hypothesis for the non conformity of the measured kinetics with the theoretical model is that in the temperature range considered the reactions are still activation controlled or in a transition zone, and should become diffusion limited only at lower temperatures and higher viscosities.

Monitoring dry-curing of S. Daniele ham by magnetic resonance imaging

S. Daniele hams were collected at different stages during dry-curing and submitted to magnetic resonance imaging (MRI) according to the acquisition Spin-Echo sequences T1 and T2. The intensity of the MR signals in the images of the Semimembranosus, Semitendinosus, Rectus femoris and Biceps femoris muscles of the hams was computed and expressed in grey levels. Muscles were also submitted to traditional analyses, including aw, soluble solids, sodium chloride, total and water soluble nitrogen. T1 and T2 MR signals well described the evolution of the phenomena occurring in the different muscles during dry-curing. MR signal acquired in T2 mode well correlated with traditional indicators in Semitendinosus, Rectus femoris and Biceps femoris muscles. Predictive models estimating the value of aw, moisture, salt content and proteolysis extent on the basis of the MR signal intensity were proposed.

Shelf Life Modeling of Photosensitive Food : The Case of Colored Beverages

A new approach to shelf life modeling of photosensitive foods was developed taking into consideration the example of a saffron-containing yellow beverage highly prone to oxidative photobleaching. The beverage was exposed to different light levels at increasing temperatures. During exposure, samples were analyzed for bleaching rate, pigment content, and pigment degradation products. The results obtained clearly showed that shelf life testing of light-sensitive foods must take into proper account the effect of light. In addition, for these foods, shelf life models based on the sole accelerating effect of temperature may be misleading. By contrast, the concomitant exploitation of the accelerating effects of both light and temperature was used to develop and validate a simple model correctly predicting the shelf life of the beverage under actual storage conditions. The methodology proposed may allow solving of the difficult task of predicting shelf life of photosensitive foods usually marketed in the presence of light.