Filipa V.M. Silva

Bio: Filipa V.M. Silva is an academic researcher from University of Auckland. The author has contributed to research in topics: Pascalization & Pasteurization. The author has an hindex of 30, co-authored 90 publications receiving 2481 citations. Previous affiliations of Filipa V.M. Silva include Cardiff University & Catholic University of Portugal.

Alicyclobacillus acidoterrestris spores in fruit products and design of pasteurization processes

Abstract: Alicyclobacillus acidoterrestris is a thermoacidophilic, non-pathogenic and sporeforming bacterium which has been found in commercial pasteurized fruit juices in the past. Only few and recent studies were available in the literature, since only in 1984 Cerny et al. [Cerny, G., Hennlich, W., & Poralla, K. (1984). Fruchtsaftverderb durch bacillen: isolierung und charakterisierung des verderbserregers. Z. Lebensmitt. Unters. Forsch. 179, 224–227] reported a spoiled aseptically packaged apple juice with A. acidoterrestris and in 1987 Deinhard et al. [Deinhard, G., Blanz, P., Poralla, K., & Altan, E. (1987). Bacillus acidoterrestris sp. nov., a new thermotolerant acidophile isolated from different soils. Systematic and Applied Microbiology, 10, 47–53] named first this species. Detection and identification methods for A. acidoterrestris were reviewed and data regarding heat resistance of spores and growth in fruits were collected. Finally, a new methodology to design pasteurization processes for high acidic fruit products is presented.

Target Selection in Designing Pasteurization Processes for Shelf-Stable High-Acid Fruit Products

Abstract: This study is focused on the search for targets and criteria for the design of pasteurization processes for high-acid shelf-stable fruit products, such as juices, nectars, pastes, purees, concentrates, jams, jellies, etc. First, an overview of pasteurization is presented and then, frequently used targets for pasteurization processes are reviewed. Enzymes naturally present in fruits, in decreasing order of heat resistance, were pectinesterase, peroxidase, and polyphenoloxidase, and they may be used as pasteurization targets. The heat resistance of each enzyme is strongly dependent on its fruit origin. The most heat resistant micro-organisms capable of spoiling high acid fruit products include ascospores of Neosartorya fischeri, Byssochlamys nivea, Talaromyces flavus, Eupenicillium javanicum, and Byssochlamys fulva moulds, as well as bacterial spores of Clostridium butyricum, Bacillus coagulans, and Bacillus megaterium. These micro-organisms, spores, and enzymes were, in general, less heat resistant than th...

Colour Measurement and Analysis in Fresh and Processed Foods: A Review

Abstract: Colour is an important quality attribute in the food and bioprocess industries, and it influences consumer’s choice and preferences. Food colour is governed by the chemical, biochemical, microbial and physical changes which occur during growth, maturation, postharvest handling and processing. Colour measurement of food products has been used as an indirect measure of other quality attributes such as flavour and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. This review discusses the techniques and procedures for the measurement and analysis of colour in food and other biomaterial materials. It focuses on the instrumental (objective) and visual (subjective) measurements for quantifying colour attributes and highlights the range of primary and derived objective colour indices used to characterise the maturity and quality of a wide range of food products and beverages. Different approaches applied to model food colour are described, including reaction mechanisms, response surface methodology and others based on probabilistic and non-isothermal kinetics. Colour is one of the most widely measured product quality attributes in postharvest handling and in the food processing research and industry. Apart from differences in instrumentation, colour measurements are often reported based on different colour indices even for the same product, making it difficult to compare results in the literature. There is a need for standardisation to improve the traceability and transferability of measurements. The correlation between colour and other sensory quality attributes is well established, but future prospects exist in the application of objective non-destructive colour measurement in predictive modelling of the nutritional quality of fresh and processed food products.

Biofilms in the Food Industry: Health Aspects and Control Methods

Abstract: Diverse microorganisms are able to grow on food matrixes and along food industry infrastructures. This growth may give rise to biofilms. This review summarizes, on the one hand, the current knowledge regarding the main bacterial species responsible for initial colonization, maturation and dispersal of food industry biofilms, as well as their associated health issues in dairy products, ready-to-eat foods and other food matrixes. These human pathogens include Bacillus cereus (which secretes toxins that can cause diarrhea and vomiting symptoms), Escherichia coli (which may include enterotoxigenic and even enterohemorrhagic strains), Listeria monocytogenes (a ubiquitous species in soil and water that can lead to abortion in pregnant women and other serious complications in children and the elderly), Salmonella enterica (which, when contaminating a food pipeline biofilm, may induce massive outbreaks and even death in children and elderly), and Staphylococcus aureus (known for its numerous enteric toxins). On the other hand, this review describes the currently available biofilm prevention and disruption methods in food factories, including steel surface modifications (such as nanoparticles with different metal oxides, nanocomposites, antimicrobial polymers, hydrogels or liposomes), cell-signaling inhibition strategies (such as lactic and citric acids), chemical treatments (such as ozone, quaternary ammonium compounds, NaOCl and other sanitizers), enzymatic disruption strategies (such as cellulases, proteases, glycosidases and DNAses), non-thermal plasma treatments, the use of bacteriophages (such as P100), bacteriocins (such us nisin), biosurfactants (such as lichenysin or surfactin) and plant essential oils (such as citral- or carvacrol-containing oils).

Modified atmosphere packaging of fresh produce: Current status and future needs

Abstract: Fresh produce is more susceptible to disease organisms because of increase in the respiration rate after harvesting. The respiration of fresh fruits and vegetables can be reduced by many preservation techniques. Modified atmosphere packaging (MAP) technology is largely used for minimally processed fruits and vegetables including fresh, “ready-to-use” vegetables. Extensive research has been done in this research area for many decades. Oxygen, CO 2 , and N 2 , are most often used in MAP. The recommended percentage of O 2 in a modified atmosphere for fruits and vegetables for both safety and quality falls between 1 and 5%. Although other gases such as nitrous and nitric oxides, sulphur dioxide, ethylene, chlorine, as well as ozone and propylene oxide have also been investigated, they have not been applied commercially due to safety, regulatory, and cost considerations. Successful control of both product respiration and ethylene production and perception by MAP can result in a fruit or vegetable product of high organoleptic quality; however, control of these processes is dependent on temperature control.