Sónia Marília Castro

High pressure extraction of phenolic compounds from citrus peels

This study evaluated the effect of high pressure processing on the recovery of high added value compounds from citrus peels. Overall, the total phenolic content in orange peel was significantly (P < .05) higher than that in lemon peel, except when pressure treated at 500 MPa. However, lemon peel demonstrated more antioxidant activity than orange peel. Pressure-treated samples (300 MPa, 10 min; 500 MPa, 3 min) demonstrated higher phenolic content and antioxidant activity comparatively to the control samples. For more severe treatments (500 MPa, 10 min), the phenolic content and antioxidant activity decreased in both lemon and orange peels.

Effect of high pressure on growth and bacteriocin production of Pediococcus acidilactici HA-6111-2

This study was aimed to investigate the effect of high pressure processing (HPP, 200–600 MPa) on the (i) survival of Listeria innocua and Pediococcus acidilactici HA-6111-2; (ii) production of bacteriocin bacHA-6111-2 and (iii) activity of bacteriocin against untreated and pressure-treated L. innocua cells. Inactivation of P. acidilactici was observed for pressures of >300 MPa. However, at this pressure level, L. innocua was more sensitive. Bacteriocin crude extract was pressure stable, with a decrease for pressures of ≥400 MPa. Pressures of ≤200 MPa did not affect bacteriocin production when compared with non-pressure-treated cells, whereas higher pressures caused a 2- to 4-fold decrease on the maximum level of bacteriocin production. Growth curves of P. acidilactici were fitted with the modified Gompertz model. The lag phase period depended on the magnitude of the pressure applied: there was a delay in the exponential phase as pressure increased and, as a consequence, in the beginning of bacteriocin production. Since P. acidilactici HA-6111-2 and its bacteriocin have shown resistance to pressures up to 300–400 MPa, they could be used in combination with HPP in order to improve food safety.

High-Pressure Processing of Fruits and Fruit Products

In the last decade, the food industry has seen a high rate of commercial expansion of the use of pressurized products. This is mainly due to the natural, fresh, and raw-like characteristics (sensorial, nutritional, and functional) that can be obtained after cold high pressure pasteurization. Foods with a high acid content, such as fruits, are particularly good candidates for high pressure processing. Color, flavor and texture are important quality characteristics of fruits and fruit products as they are major factors affecting sensory perception and consumer acceptance. Commercially, higher pressures are preferred, around 600 MPa, as a means of accelerating the inactivation process. The pressure resistance of vegetative microorganisms often reaches a maximum at ambient temperatures, so the initial temperature of the food prior to high pressure processing can be reduced or elevated to improve inactivation at the processing temperature. This chapter reviews the main findings related to the effect of high pressure processing on fruits and fruit-based products, from 2004 onwards.

Antimicrobial activity of ethanolic extract of propolis in “Alheira”, a fermented meat sausage

Abstract The objective of this study was to evaluate the efficacy of an ethanolic extract of propolis (EEP) in the control of Listeria innocua PHLS 2030c (as a surrogate for Listeria monocytogenes) during storage of Alheira at 4°C. Total phenolic content was evaluated to determine the minimal inhibitory concentration of EEP against the growth of L. innocua by the agar dilution method. Alheiras were manufactured by incorporating EEP (0.28 mg/mL) and pathogenic bacteria and storage during 62 days at 4°C. Growth of L. innocua was determined during storage. The behaviour of L. innocua in the food matrix was significantly affected (p < 0.01) by the addition of EEP. The ethanolic extract of propolis reduced the Listeria population to below the detection limit of the technique after 8 days of storage. These results suggest that incorporation of EEP in a food susceptible to Listeria contamination may be an interesting alternative to existing chemical preservatives and can extend the shelf life of these products.

Chapter 8 – Environmental Footprint of Emerging Technologies, Regulatory and Legislative Issues

Abstract Consumers are more demanding, better educated in terms of food quality and nutritional aspects, and forcing producers along with regulatory agencies to search for alternative processing technologies. Some of these technologies like high pressure, pulsed electrical fields, supercritical CO 2 , ultrasound, ozone, or plasma treatment are at industrially use, pilot scale, or even at the edge of application, but the most successful ones at the moment, with already a wide variety of commercial products, are high hydrostatic pressure and pulsed electrical fields. These technologies offer better products, both “natural” in terms of fresh-like flavor and ingredients and safe with extended shelf-life. This tendency leads to the need for a global regulation system that ensures quality of food regardless of country of origin and, at the same time, without compromising safety. In addition to this system, there should be governing bodies that regulate and monitor the enforcement of these food-processing regulations, to avoid regulations that often only apply to countries belonging to specific organizations. Together with food legislation concerns, sustainable food manufacturing and related efficient energy use have also became priorities of the food industries. While conventional preservation processes (e.g., canning, freezing, drying) mainly use thermal energy, more complex processes use mechanical, electromagnetic, electrical, and other forms of energy, which can reduce the energy consumption. Indeed the efficient use of resources in food industry is a critical element for the future generations for sustainable food processing, but the impact of energy requirements in emerging technologies has not been a matter of intense discussion. The objective of this chapter is to provide a concise overview of environmental footprint of emerging technologies, namely high-pressure processing and pulsed electric fields, and their current related food legislation status in various countries.

Enhancement of bacteriocin production and antimicrobial activity of Pediococcus acidilactici HA-6111-2

The effect of sequential treatments of pressure (50–150 MPa, 10 oC, 5 min) and temperature (57 oC, 15 min) on the survival and bacteriocin production of Pediococcus acidilactici HA-6111-2 cells in the exponential growth phase was assessed. The growth curves were fitted with the modified Gompertz model, and the estimated maximum specific growth rate was considered to be pressure dependent. A delay in the maximum value of bacteriocin production was registered for more severe pressure conditions, but it was found more notorious for pressure followed by temperature treatments. At lower pressure intensity treatment, regardless of the application order, there was an enhancement of bacteriocin production per cell when compared to the control while maintaining the maximum production value. Bacteriocin production after the treatments can be described by an exponential model.

Effect of pressure and blanching treatments on endogenous enzymatic activity and vitamin C content of bell pepper fruit

The effect of high pressure and blanching treatments on green bell pepper was studied. Both processes caused changes on pectin methylesterase activity and vitamin C and protein contents. Polygalacturonase activity was not detected in any of the samples studied. There seems to be no significant difference caused by both types of processing.