Browsing by Author "Duarte, Ricardo V."
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- Hyperbaric storage at room temperature with several short intermittent interruption periods at atmospheric pressure results in similar microbial growth inhibition and inactivation as without interruptionPublication . Duarte, Ricardo V.; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.In order to study the possible effect of several compressions and decompressions (C/D) cycles performed during hyperbaric storage (HS) in microbial behaviour, raw milk was stored under 75 MPa at room temperature (RT) for 31 days, under three different total C/D cycles conditions, 5, 31 and 93. The different C/D cycles achieved similar microbiological counts reduction for the same sampling period, independently of the number of C/D cycles, with Dp-values around 3.5 and 19 days for Enterobacteriaceae and total aerobic mesophiles, respectively, reaching similar microbial levels at the end of the storage period. These results contribute to enhance HS research, allowing the use of a single vessel with several samples to be taken along time, since several C/D cycles have no effect on results, thus leading to faster research advances in the field of HS.
- Hyperbaric storage of raw milk at room temperaturePublication . Duarte, Ricardo V.; Lemos, Álvaro T.; Delgadillo, Ivonne; Gomes, Ana Maria; Saraiva, Jorge A.
- A microbiological perspective of raw milk preserved at room temperature using hyperbaric storage compared to refrigerated storagePublication . Duarte, Ricardo V.; Pinto, Carlos A.; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.The effects of hyperbaric storage (HS, 50–100 MPa) at room temperature (RT) on endogenous and inoculated pathogenic surrogate vegetative bacteria (Escherichia coli, Listeria innocua), pathogenic Salmonella enterica and bacterial spores (Bacillus subtilis) were assessed and compared with conventional refrigeration at atmospheric pressure for 60 days. Milk stored at atmospheric pressure and refrigeration quickly surpassed the acceptable microbiological limit within 7 days of storage, regarding endogenous microbiota, yet 50 MPa/RT slowed down microbial growth, resulting in raw milk spoilage after 28 days, while a significant microbial inactivation occurred under 75–100 MPa (around 4 log units), to counts below 1 log CFU/mL throughout storage, similar to what was observed for B. subtilis endospores. While inoculated microorganisms had a gradually counts reduction in all HS conditions. Results indicate that HS can not only result in the extension of milk shelf-life but is also able to enhance its safety and subsequent quality. Industrial relevance: This new preservation methodology could be implemented in the dairy farm storage tanks, or during milk transportation for further processing, allowing a better microbial control, than refrigeration. This methodology is very promising, and can improve food products shelf-life with a considerable lower carbon foot-print than refrigeration.
- Nutritional and quality evaluation of hyperbaric stored fresh cheesesPublication . Duarte, Ricardo V.; Casal, Susana; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.Cow's and goat's fresh cheese (FC), two highly perishable dairy products, were stored under hyperbaric storage at room temperature (HS/RT, 50–100 MPa) and compared with refrigeration (RF, 4 °C), for 60 days. Under HS/RT (≥75 MPa), FCs presented a more stable volatile organic and fatty acid profiles, and reduced lipid oxidation rate, particularly for cow's FC, resembling more to FC prior storage, contrarily to refrigerated cheeses. No changes were observed for total protein, but free amino acids increased over time after 60 days at 75/RT of 13- and 16-fold, and at 100/RT of 14- and 8-fold, respectively in cow's and goat's FC, which may have contributed to increased protein digestibility (5.2%) observed for goat's FC after 60 days at 100/RT. In general, the results indicate the overall increased preservation performance achieved by HS/RT for cow's and goat's FC when compared with RF, slowing down FC matrix degradation, possibly leading to considerable shelf-life extension.
- Nutritional, physicochemical, and endogenous enzyme assessment of raw milk preserved under hyperbaric storage at variable room temperaturePublication . Duarte, Ricardo V.; Casal, Susana; Silva, José A. Lopes da; Gomes, Ana; Delgadillo, Ivonne; Saraiva, Jorge A.Raw milk (a highly perishable food) was preserved at variable room temperature (RT) under hyperbaric storage (HS) (50-100 MPa) for 60 days and compared with refrigeration (RF) under atmospheric pressure (AP) on quality, nutritional, and endogenous enzyme activity parameters. Overall, a comparable raw milk preservation outcome was observed between storage under AP/RF and 50/RT after 14 days, with similar variations in the parameters studied indicating milk degradation. Differently, even after 60 days (the maximum period studied) under 75-100/RT, a slower milk degradation was achieved, keeping most of the parameters similar to those of milk prior to storage, including pH, titratable acidity, total solid content, density, color, viscosity, and volatile organic and fatty acid profiles, but with higher free amino acid content, signs of an overall better preservation. These results indicate an improved preservation and enhanced shelf life of raw milk by HS/RT versus RF, showing HS potential for milk and highly perishable food preservation in general.