Loading...
3 results
Search Results
Now showing 1 - 3 of 3
- Freshness assessment and shelf-life prediction for Seriola dumerili from aquaculture based on the quality index methodPublication . Freitas, Jorge; Vaz-Pires, Paulo; Câmara, José S.Fish and fish-based products are easily perishable foods due to different factors, including fragile organization, abundant endo-enzymes, psychrophilic bacteria, and impact of pre-harvest operations, that contribute to reducing its value. Therefore, a timely effective method for fish freshness and shelf-life evaluation is important. In this context, this study aimed to develop a sensory scheme based on the Quality Index Method (QIM) (sensory table and point system) for freshness monitorization and shelf-life prediction for Seriola dumerili from aquaculture in Madeira Island. Evaluation of appearance, texture, eyes, and gills was performed during 20 days of storage on ice (0 ± 1 ◦C). The shelf-life prediction was supported by the analysis of microorganisms (total viable colonies, TVC, counts), texture (Torrymeter), and production of trimethylamine (TMA), evaluated by HS-SPME–GC–MS and validated according to Association of Official Analytical Chemists AOAC guidelines. The result is a QIM scheme with 25 demerit points, where zero indicates total freshness. From the integration of sensory analysis, microbial growth at the time of rejection (TVC, 108 cfu/cm2 and H2S producers, 107 cfu/cm2 ), texture (Torrymeter value < 8), and TMA analyses (>12.5 mg/100 g), shelf-life was estimated as 12 days (±0.5 days). The obtained results show the high-throughput potential of the developed method for fish freshness assessment and shelf-life prediction. This QIM scheme is a secure way to measure quality and provide users with a reliable standardized fish freshness measure.
- Establishment of authenticity and typicality of sugarcane honey based on volatile profile and multivariate analysisPublication . Silva, Pedro; Freitas, Jorge; Silva, Catarina L.; Perestrelo, Rosa; Nunes, Fernando M.; Câmara, José S.Sugarcane honey (SCH) is a black syrup produced in Madeira Island widely known for their excellent quality being used in traditional pastry and confectionery. However, its notoriety has been affected by circumstances in which some producers do not guaranty the product quality. The purpose of this study was to establish, for the first time, the volatomic profile of SCH produced by certified and non-certified producers in order to define their authenticity and typicality as useful platform to ensure SCH safety, protect consumer interests and fight the continuous problems of food fraud and adulteration. Solid-phase microextraction in headspace mode (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was applied as high throughput approach for extraction, separation and identification of SCH volatile compounds. The extraction technique was optimized for nature of stationary phase, extraction temperature, extraction time, and validated according with IUPAC and AOAC guidelines. Different volatomic fingerprints for SCH from certified and non-certified producers were recognized, being identified up to 87 volatile organic compounds (VOCs) belonging to distinct chemical classes, mainly aldehydes, alcohols, ketones and furans. One-way ANOVA analysis showed the existence of 18 VOCs with statistically significant differences between volatile profiles from certified and non-certified producers. Principal component analysis (PCA) and linear discriminant analysis (LDA) differentiate and discriminate the samples from both type of producers. According to the obtained results, the followed strategy revealed an effective way to establish the authenticity and typicality of SCH, providing useful information to producers that might therefore be used to improve the SCH quality and a powerful platform to promote a European certification application.
- A fast and environment-friendly MEPS PEP /UHPLC-PDA methodology to assess 3-hydroxy-4,5-dimethyl-2(5H)-furanone in fortified winesPublication . Freitas, Jorge; Perestrelo, Rosa; Cassaca, Rubina; Castillo, Mariangie; Santos, Mariana; Pereira, Jorge; Câmara, José S.Sotolon is widely associated with the quality of fortified aged wines, and has also been linked to premature oxidative aging (premox). Here we developed a single, fast and environmental-friendly microextraction by packed sorbent ultra-high pressure liquid chromatography analysis (MEPS/UHPLC-PDA) for sotolon quantification in different wines. The best extraction conditions (loading three times 250μL samples through the MEPSPEP sorbent and elution with 100μL of 50% MeOH) were combined with a fast UHPLC separation (5min separation using acidified 10% MeOH isocratic flow in a CORTECS C18 column) to allow unparalleled minimum sample and solvents volumes usage. The validated methodology showed good linearity (r(2)>0.993) and precision (<5.6%); high recovery (>81%) and detection limits (0.45-2.51μg/L) far below sotolon odor threshold for any type of wine. The methodology was successfully applied to selected white table and Madeira wines, encompassing therefore a wide range of alcohol and sugar contents. Furthermore, as far we may know, this is the first time a single methodology can be used to assess both wine aging or premox according to the type of wine.