Percorrer por autor "Silva, Beatriz Nunes"
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- Antifungal capacity of commercial flavouring agents against spoilage yeastsPublication . Silva, Beatriz Nunes; Carvalho, Teresa Bento de; Azevedo, Miguel; Silva, Beatriz; Teixeira, PaulaIntroduction: Yeasts are involved in the spoilage of foods and beverages, causing undesirable changes in the physicochemical and sensory properties of the products. Prevention of food spoilage requires good manufacturing and hygiene practices, but additives are also frequently used to hinder yeast growth. Nowadays, consumers and companies are moving from chemical additives towards other options that can be perceived as more natural and less harmful to human health: biopreservatives. Objectives: Assess the antifungal capacity of three commercial flavouring agents against: four Zygosaccharomyces yeasts isolated from pastry fillings (Z. bailii, Z. parabailii, Z. bisporus and Z. rouxii); two yeasts isolated from thermo-sealed packaging (Rhodotorula mucilaginosa and an unidentified yeast). Conclusions: While the commercial extracts did not exhibit antifungal activity against all the tested yeasts, the results are still encouraging in several cases. These natural alternatives may be useful to replace the chemical preservatives currently used in the pastry industry (such as potassium sorbate), as they may hamper yeast growth during the manufacturing process.
- Chicken breasts packaged under different gas compositions reveal distinct microbial communities and olfactive characteristicsPublication . Silva, Beatriz Nunes; Ferreira, Ricardo M.; Monteiro, Maria João; Moen, Birgitte; Jensen, Merete Rusås; Langsrud, Solveig; Barbosa, Joana; Mena, Cristina; Teixeira, Susana; Poças, Fátima; Teixeira, Paula
- Clean label antimicrobial strategies for fungal spoilage of pastry fillingsPublication . Carvalho, Teresa Bento de; Silva, Beatriz Nunes; Azevedo, Miguel; Silva, Beatriz; Teixeira, PaulaIntroduction: Fungal spoilage is a key concern for the food industry, leading to hefty economic losses Consequently, the food waste that follows is also a grave matter not only due to its social or humanitarian aspect but also its environmental impact. Objectives: The aim of this study was to assess the antifungal activity of commercial clean label alternatives to potassium sorbate against moulds isolated from a pastry filling. Methodology: Isolation of fungi from a contaminated product used in antimicrobial activity tests of clean label preservatives. Results and discussion: Fungal growth was not completely inhibited at the concentrations recommended by the manufacturers. The antimicrobial agents are still effective and, therefore, a promising alternative to traditional chemical preservatives for the pastry industry. Conclusions: In this context, the clean label movement is trending to offer natural spoilage control strategies while having their organoleptic characteristics and, most importantly, safety in sight. Future research into the application of these antimicrobial compounds in pastry fillings is an important step to guarantee their efficacy and application in the industry.
- Comparing growth and survival kinetics of persistent and sporadic strains of listeria monocytogenes from alheira sausagePublication . Meneses, Rui; Pereira, Catarina; Ferreira, Vânia; Magalhães, Rui; Barbosa, Joana; Silva, Beatriz Nunes; Teixeira, PaulaMotivation: L. monocytogenes is known to persist in food processing environments, with some strains being routinely isolated (persistent), while others are only occasionally found (sporadic). This raises the question: Are persistent strains more resistant to stress conditions compared to sporadic strains from similar sources? Objective: To investigate the effect of food processing related stresses (pH=6 and 8% NaCl) on the behaviour of L. monocytogenes isolates from alheira sausage, compared to a set of reference conditions (37 °C, 0% NaCl, pH=7). Results: Compared to the reference conditions: High salinity conditions → significantly longer lag times and lower μmax for all isolates Low pH (pH = 6) reduced μmax but also shortened the lag phase for most isolates These sub-optimal conditions were insufficient to promote pathogen decay The persistent strains #2981 and #3048 do not exhibit a particular behavior nor appear to have increased resistance against the conditions tested This result is aligned with recent research. Conclusions: No significant differences were found between persistent and sporadic strains, suggesting that persistence events may not be explained by a better aptitude for growth. However, further research with a larger number of isolates is needed.
- Consumer-driven shelf-life determination and consumer perception of chicken samplesPublication . Joy, Aira Aquino; Kasza, Gyula; Szakos, Dávid; Császár-Biró, Ágnes; Izsó, Tekla; Fügedi, Eszter; Langsrud, Solveig; Moen, Birgitte; Berget, Ingunn; Måge, Ingrid; Gaarder, Mari Øvrum; Almli, Valérie Lengard; Teixeira, Paula; Silva, Beatriz NunesDuring storage, raw chicken meat produces off-odours and off-tastes due to microbial growth. The speed of this process mainly depends on storage conditions (temperature, moisture, and presence of preservatives), as well as the initial contamination. Consumers consider the product unfit for consumption once it reaches a certain level of spoilage. The expiry date is one of the key quality and safety indicators that producers provide for consumers. However, determining the actual expiry date can be challenging, as many factors are at play, such as batch variation and storage environments, which contribute to the gradual spoilage of products. Currently, research linking storage time, microbial growth, sensory changes, and consumer perception is limited. Studies investigating the various aspects of product spoilage are necessary for determining the appropriate shelf life for raw chicken. This study aims to address the following objectives: 1) Determine consumers’ sensory perception of chicken samples stored under different time points and conditions and identify the time points at which consumers deem the products unfit for consumption. 2) Link consumer scores of sensory quality and fitness for consumption to measurable parameters that can be used to establish shelf life (e.g., bacterial counts, microbiota, sensory profile). 3) Integrate consumer, sensory, and microbial results from the laboratory experiment into shelf-life determination methods applicable to the food industry. The experiment was conducted in three countries: Hungary, Norway, and Portugal. Chicken samples were obtained from one local producer per country, and the same batch of chickens was used for the analysis. A cutting-edge reversed storage design was employed; with sampling plans tailored to each country based on the original expiration date set by the producer. The plan included storing the samples in their original packaging at different time points and at two storage temperatures: 4 °C and 8 °C. The samples were tested for total microbiological load and microbiome composition, and at the end of the shelf-life storage test, all samples were used for consumer and semi-trained sensory analyses. For the consumer analysis, a minimum of 120 participants were recruited in each country to evaluate the degree of disliking and overall acceptance of the samples. Meanwhile, in the semi-trained test, a 9-point hedonic scale was used to assess the intensity of 11 sensory attributes. Results from the consumer test showed that in Norway and Portugal, higher intensity scores were observed for samples stored at abusive temperatures (8 °C). In Hungary, however, storage conditions did not significantly affect the intensity scores. An increase in intensity scores and disliking was observed in Hungary between 3 and 6 days, in Norway between 7 and 15 days (8 °C) and at 18 days (4 °C), and in Portugal at 7 days (8 °C) and between 7 and 11 days (4 °C). For the semi-trained panel test, all sensory attributes related to spoilage were highly correlated in all countries. The most important attributes contributing to perceived spoilage were total intensity, cloying, sour/fermented, ammonia/burnt/pungent, and sulphur. The Photobacterium was discovered through microbiota analysis, but it was likely underestimated by conventional PCA total count methods, as we cannot be certain what grew on the plates. The total intensity score from the semi-trained panel test seems to depend primarily on the total bacterial counts and the aggregated bacterial load. For industry recommendations, total intensity can be suggested as a reliable indicator for producers. However, variability observed in microbial analyses is not always detectable through sensory analysis, so further investigation is needed. The majority of consumers accepted all samples across all countries. The data support that, provided raw chicken is stored under proper conditions, an additional 2 days of shelf life can be recommended for Norwegian and Portuguese chicken samples. Additionally, we will report the results of a recently concluded digital survey in Hungary which was also done in 9 other European countries. A total of 1006 respondents were gathered in Hungary using stratified random sampling and a predefined criterion. The questionnaire was divided in different sections involving aspects like purchase decision making, food waste data, new innovations in measuring shelf-life, acceptability of two different food preservation methods, and whether they will support government and policy initiatives to support the improvement of shelf life and reduce food waste.
- Explorative analysis of microbial communities in chicken productionPublication . Måge, Ingrid; Rasmussen, Morten Arendt; Teixeira, Paula; Moen, Birgitte; Sousa, Clara Santana; Silva, Beatriz Nunes; Fagerlund, Annette
- Explorative analysis of microbial communities in chicken productionPublication . Måge, Ingrid; Rasmussen, Morten Arendt; Teixeira, Paula; Silva, Beatriz Nunes; Sousa, Clara Santana; Fagerlund, Annette; Moen, BirgitteContext: This study is part of the MICROORC project, which aims to reduce food waste by monitoring and utilizing microbiomes in the food processing chain. A key aspect of the project involves mapping microbiome variations along the chicken production line, to identify patterns and potential key control points. Research question: What is the best chemometric tool for exploring variations in complex industrial microbiome data, and interpreting these variations with respect to time, space, and microbial signatures? Methods: The data can be structured either in a two-way or three-way array. The rows in the batch mode represent 28 independent production batches (2 factories x 7 production days x 2 times a day). There are varying numbers of replicates per batch and sampling location, which are averaged in the three-way representation but kept intact in the two-way data. The two-way array was analysed using ASCA with factors Factory, Location and Time of day, while the three-way array was decomposed by PARARAC. The three-way array contains 4% missing elements, as some locations are missing for some batches. ASCA Results: Differences between factories and locations had the highest contribution to the microbial variation. Interestingly, there was also systematic variation du to time of day. SCA was performed to interpret these differences, revealing that the shift along the processing line is related to different genera. The difference between factories (top row) is largest in the clean zone, while the difference between early and late batches (bottom row) is largest in the scalding water. PARAFAC Results: A PARAFAC model with two components explains 23% of the variation in the data. In line with the ASCA result, the loadings reveal that the first component represents the difference between factories, which increases along the processing line. The second component represents variation that also differs between factories, and separates early and late batches in factory A. Conclusion: The main systematic variation is the difference between factories, which increases along the production line. This is represented in both models. The more subtle differences between early and late batches are more challenging to understand, and the methods provide different perspectives on this. Both methods indicate that the difference between early and late batches is largest in the scalding water but also evident in the latest locations. While the PARAFAC model indicates that this effect is only found in factory A, the ASCA results suggest that it is present in both factories. The large residual variation within both models stems from the natural uncertainty within industry level microbial data, as well as from variation between sampling days throughout the year, which is particularly interesting for the project and will be investigated further.
- Impact of salt reduction on lactic acid bacteria and total viable counts in chouriçãoPublication . Barbosa, Joana; Carvalho, Teresa Bento de; Komora, Norton; Azevedo, Maria A.; Silva, Beatriz Nunes; Teixeira, PaulaIntroduction: Salt has been used as a food additive and preservative in meat products for many centuries. As excessive sodium intake can lead to cardiovascular and cerebrovascular diseases, primary liver cancer, and atrial fibrillation, low-salt reformulations of traditional meat products have been developed. Nevertheless, while salt reduction may address the issue of excessive sodium intake, the effects of using reduced amounts of salt must be carefully considered and raise questions regarding the microbiological stability and shelf-life of the products. Purpose: This study aimed to assess the impact of reducing the salt content in the formulation of sliced chourição on the growth of Total Viable Counts (TVC) and Lactic Acid Bacteria (LAB) during the shelf-life of the product. Discussion: An increase in the number of TVC (Figure 1) and LAB (Figure 2) was observed over the 60 days of storage at the two temperatures tested, although this increase was more pronounced at 10 °C (abuse temperature). Regarding TVC (Figure 1), an increase in the bacterial levels was observed in the salt-reduced prototypes compared to the standard samples, particularly in samples stored at 10 °C (4 and 6-log cycle increase for the traditional formulation (chourição standard), and 6 and 7-log cycle increase for salt-reduced prototypes, at 4 °C and 10 °C, respectively. Regarding LAB (Figure 2), an increase of 4 and 5-log cycles was observed at 4 °C and 10 °C, respectively, for the traditional chourição, while an increase of 5-log cycles was observed at both temperatures for the salt-reduced salt formulation. Conclusions: Salt plays a critical role in the preservation of meat products. Therefore, product reformulation that involves salt reduction must ensure the same degree of economic and technological feasibility, and, most importantly, maintain the microbiological quality of the final product. New reduced-salt formulations must be further studied, such as physico-chemical characteristics, sensory analysis and challenge tests with target foodborne pathogens, and new hurdles should be introduced or improved in chourição production to achieve the same microbiological stability and shelf-life.
- Microbial contamination in a chicken slaughterhouse: insights from sampling throughout productionPublication . Silva, Beatriz Nunes; Moen, Birgitte; Jensen, Merete Rusås; Langsrud, Solveig; Teixeira, PaulaMotivation: In some slaughterhouses, the high volume of chicken processed (~190k chicks/day) creates a challenging environment where contamination of the carcasses may be difficult to avoid, even with proper hygienic measures. Goal: To evaluate microbial contamination at various locations in the slaughterhouse throughout the production day. Results: Between the first and the last production batch, the microbial load of the chicken cages and of the scalding water decreased. Microbial load of blades remain stable throughout production. No differences between Belts_early vs. Belts_late. This suggests that cutting blades and each conveyor belt do not become increasingly contaminated throughout production. Belt_early is the most different group, especially compared to Cages and Scalding water. The biggest and most significant difference was Belt_early vs. Cages_early. Scalding water_early also differs considerably from the Belt groups. Conclusions: Large variability in microbial load at specific sampling points. Hygiene samples with higher microbial levels than samples during production ? must be investigated! High volume of carcasses processed and lack of time to stop production and sanitize the production line pose a hindrance to reducing microbial levels in the final product.
- Microbiological profile of vegan and vegetarian meat analogues from the Portuguese retail marketPublication . Tomé, Elisabetta; Barbosa, Joana; Silva, Beatriz Nunes; Carneiro, Ana; Mena, Cristina; Ferreira, Ricardo; Poças, Fátima; Teixeira, PaulaMotivation: Meat analogues, especially those of plant origin, are generally high in protein, high in water activity (aw > 0.95) and have a mildly acidic pH (pH > 5.5) (Kabisch et al., 2024), making these products highly susceptible to microbial spoilage. With the current increase in consumption of meat analogues, their food safety aspects need to be considered and the question arises: can meat analogs pose a food safety concern? Objective: To determine the microbiological status of plant meat analogues at the retail level in Portugal. To obtain insight into the levels of contamination and the bacterial contaminants associated with these products. Methodology: Ten vegetarian or vegan meat analogues produced by different companies made from soy (n = 6), milk/eggs (n = 2), wheat (n = 1) or lupine (n = 1), were purchased in 2024 from local supermarkets in Porto, Portugal. Of these, seven products required heating/cooking, and three were ready-to-eat (RTE). Microbiological analysis and physicochemical characterisation (pH and aw) of the products was carried out at five different times during the shelf-life indicated on packaging and up to two weeks after the expiry date. Total viable counts, lactic acid bacteria, Listeria monocytogenes and sulfite-reducing clostridia spores were determined. Results: Throughout the analyses, for all samples, the pH ranged between 4.72 and 6.25, and the aw ranged between 0.92 and 0.97. These values are insufficient to prevent microbial growth.