Elisabete M. C. Alexandre

Incorporation of strawberries preparation in yoghurt: impact on phytochemicals and milk proteins.

An immediate decrease in the total antioxidant activity (23%) and total phenolic content (14%) was observed after addition of strawberry preparations to yoghurt. The total anthocyanin content did not change immediately, but decreased 24% throughout the yoghurt shelf-life. The individual compounds, (+)-catechin (60%), (-)-epicatechin (60%), kaempferol (33%) and quercetin-3-rutinoside (29%) decreased after 24h in the yoghurt made with the strawberry preparation. During the remaining period of storage these compounds increased by 47%, 6%, 4% and 18%, respectively. Pelargonidin-3-glucoside decreased 49% after 28 d. Immediately after the addition of the strawberry preparation to yoghurt, β-lactoglobulin decreased to values lower than the limit of detection and α-lactalbumin by approximately 34%, and was reduced further slowly throughout yoghurt self-life. An immediate interaction between the carrageenan present in the strawberry preparation and β-LG was observed. The variations of both polyphenols and protein in the presence of carrageenan and the potential interactions were discussed.

Phytochemicals preservation in strawberry as affected by pH modulation

Strawberries purées are incorporated in foods and subjected to pH modulation according to the expected final food matrix. The effect of pH on strawberry polyphenols stored at 4 and 23 °C for 90 days was evaluated. Total antioxidant activity and total phenolics content were only affected by time according to a first order model. The pH 4.5 induced higher decrease in (-)-epigallocatechin gallate (71% and 79%) and quercetin-3-glucoside (29% and 36%), for both storage temperatures. For pH 2.5 and 3.0, ellagic acid increased 84% for 4 °C and 185% for 23 °C. Anthocyanins concentration changes along storage were well described by first order model. The pH value of 2.5 presented the lower kinetic constant rate where cyanidin-3-glucoside, pelargonidin-3-glucoside and pelargonidin-3-rutinoside had a k=0.04, 0.05 and 0.03 day(-1). Lower storage temperature (4 °C) and lower pH (2.5) were the best condition for the preservation of polyphenols in pasteurized strawberry during a 90-day storage period.

Emerging Technologies to Improve the Safety and Quality of Fruits and Vegetables

Consumers’ demand for increased quality standards has spurred the search for new and less aggressive processing technologies´, which permit greater retention of natural taste. As a consequence, minimal processing techniques emerged with the objective of replacing traditional preservation methods with the intention of extending shelf-life, without the detrimental effects caused by severe heating. Non-thermal methods have emerged as attractive alternatives to conventional thermal processing methods. They constitute challenging processes aiming at reducing pernicious effects of thermal methods, by preserving quality and nutritional attributes of fruits and vegetables, and yielding safe and less-perishable products. Ozone, UV-C irradiation and ultrasounds treatments are promising techniques for the fruits and vegetable industry. The application of such technologies may yield products with limited losses of color, flavor, texture and nutrients, while retaining the desired shelf-life and safety. However, the efficiency related to each safety or quality indicator depends on the product/indicator under consideration.

Comparison of Emerging Technologies to Extract High-Added Value Compounds from Fruit Residues: Pressure- and Electro-Based Technologies

Fruit consumption has significantly increased due to their attractive sensory properties and the growing recognition of its nutritional and therapeutic values. Nevertheless, several tons of fruits are processed by the food industry for the production of different products such as juices and jams, leading to the production of a great amount of fruit waste. Until a few decades ago, fruit residues were not considered a cost neither a benefit but resulted in a significant negative impact on the environment, ending up being used as animal feed, brought to landfills or sent to composting sites. The extraction of high-added value compounds from fruit residues is usually done through conventional methods, such as Soxhlet, hydrodistillation, maceration, and enzyme-assisted extraction. Although these methods are easy to perform and cheap to operate, they present several concerns mainly due to thermo-sensible compound degradation and environment pollution. Recently, new extraction technologies have been in development to improve extraction of high-value compounds, such as high pressure, pressurized liquid extraction, instantly controlled pressure drop, pulse electric fields, and high-voltage electrical discharges, as well its combinations between each other’s. These technologies are considered environmentally friendly, allow the use of lower amounts of organic solvents and the reduction in extraction time and energetic consumption, conducting to higher yields and high-quality final extracts.

Emerging technologies to extract high added value compounds from fruit residues: Sub/supercritical, ultrasound-, and enzyme-assisted extractions

ABSTRACT Food waste is a growing problem for the food industry, leading to an increase of pollution and economic problems. Fruits and vegetables are very rich in bioactive compounds having many benefits for humans. These biocompounds can be found not only in the fruit/vegetable itself but also in its wastes, after processing. Nonetheless, the conventional extraction methods are highly problematic, due to solvent consumption, long extraction time, and low extraction yields, making it necessary to develop new extraction techniques. In this review, we aim to review the most recent literature on the extraction of bioactive compounds from fruit peels and seeds, using sub/supercritical fluids, ultrasound, and enzymes.

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.

Antimicrobial activity of pomegranate peel extracts performed by high pressure and enzymatic assisted extraction

This study aimed to assess the effect of high pressure (300 and 600 MPa) and enzymatic extraction (pectinase and cellulase) on the phenolic compounds profile, antioxidant capacity and antimicrobial activity of extracts from pomegranate by-products. Antimicrobial activity against eight different strains of pathogenic and contaminant bacteria and against five beneficial bacteria including Lactobacillus and Bifidobacterium strains were determined. The maximum level of total phenolic content, as well as antioxidant capacity were observed at 300 MPa, however enzymatic extraction did not improve the extraction yields. Punicalagin isomers and bis-hexahydroxydiphenoyl-glucoside isomer were the most abundant phenolic compounds found in the extracts. All pomegranate peel extracts demonstrated selective antimicrobial activity against all pathogenic bacteria without affecting beneficial ones. Pressurized extracts presented lower minimum inhibitory concentration against Bacillus cereus and Pseudomonas aeruginosa and lower minimum bactericidal concentration against B. cereus, while, enzymatic extracts presented lower minimum bactericidal concentration for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus and Listeria monocytogenes. Principal component analyses reveled that antioxidant activity and phenolic compounds content were strongly related with antimicrobial activity. Pomegranate peels extracts obtained by high pressure extraction could so be used as a source of high added-value bioactive compounds for antioxidant and antimicrobial applications.

Effect of emergent non-thermal extraction technologies on bioactive individual compounds profile from different plant materials

Extraction is the first step for isolation and purification of interesting bioactive compounds, by mixing of the plant material with an adequate solvent. Those bioactive compounds are, usually, secondary metabolites, such as phenolic acids and flavonoids which are present in closed insoluble structures, making its extraction a challenge. There are many different traditional extraction methods, such as Soxhlet, heat reflux, and maceration. Nevertheless, due to several disadvantages, they are being replaced by new methods, using emergent technologies, such as high hydrostatic pressure, ultrasounds, pulsed electric fields, and supercritical fluids. The use of novel technologies allows enhancing mass transfer rates, increasing cell permeability as well as increasing secondary metabolite diffusion, leading to higher extraction yields, fewer impurities on the final extract, extractions at room temperature with thermo-sensitive structures preservation, use of different non-organic solvents, low energy consumption, short operation time, and have no significant or lower effect on the structure of bioactive compounds. This paper aims to review the effect of the main emergent extraction technologies (high hydrostatic pressure, pulsed electric fields, ultrasounds, and supercritical fluid assisted) on the individual profile of bioactive compounds from plant material.

Effect of high pressure on green pea seeds germination and plantlets development

The aim of this work was to study the impact of high pressure (50 MPa, 10 min) on germination of pea seeds with different imbibition times (0, 12 and 36 h). The parameters analysed were the percentage of germinated seeds, length of roots and stems, number of leaves developed and the weight of young plantlets. Peroxidase (POD), polyphenol oxidase (PPO), pectin methylesterase (PME) and total proteolytic activity were analysed in seeds after the pressure treatment and in leaves after the germination period. Results showed that 50 MPa applied during 10 min retarded the germination onset and inhibited seeds to germinate. The pressure treatment increased and decreased the length of roots and stems, respectively. The number of leaves per germinated seed decreased with the pressure treatment. Enzymatic activities of seeds showed that only total proteolytic activity was significantly reduced by pressure and only for 0 h of imbibition. POD and PPO activities determined in leaves of the plantlets increased with the pressure treatment, while PME activity also increased but only for 12 h of imbibition and total proteolytic activity decreased.