A novel approach for the determination of freshness and identity of trouts by MALDI-TOF mass spectrometry

Properly handled fish is usually marketed as “fresh fish” until day 10 after fishing. About 40% of the total fishery that is used for direct human consumption is marketed in fresh form stored at temperatures up to +2 °C. Currently, there are no validated methods available for controlling the recommended period of storage. Apart from being a potential source for food fraud, spoiled fish represents a major source of foodborne illnesses and intoxications.In this study, a rapid MALDI-TOF mass spectrometry based screening method was developed using the vitreous fluid of fish eyes as specimen for the examination of different days of storage. The vitreous fluid was collected from n = 100 freshly fished brown trouts at day 0, 3, 7, 9, and 11 post mortem (n = 20 brown trouts each day of examination). The samples were immediately measured by MALDI-TOF mass spectrometry in linear positive mode (mass range m/z 2000–20,000 Da). For quality assurance the experiment was repeated with a set of brown trouts (n = 100) originating from the same fish farm and with brown trouts (n = 100) originating from a different fish farm. For specificity testing rainbow trouts (n = 10) were examined accordingly. All obtained mass spectra were processed by means of MALDI Biotyper OC 3.1 and ClinProTools 3.0 software.The MALDI Biotyper approach showed limited applicability for the identification of the time of storage. However, it was suitable to reliably discriminate between the closely related species brown and rainbow trout. Processing by ClinProTools revealed four crucial mass peaks (m/z 2594 Da, m/z 4857 Da, m/z 4879 Da, m/z 4899 Da) which enabled a reliable differentiation between day 0 and 3, 7, 9, 11 (rate of correct identification > 90%) as well as the differentiation between day 3 and 7, 9, 11 (rate of correct identification > 72%). However, this approach showed limited applicability within the end of the tested period of storage when comparing between day 7, 9, or 11.     

Development of a rapid method based on front face fluorescence spectroscopy for the monitoring of egg freshness: 1—evolution of thick and thin egg albumens

In this preliminary study, the intrinsic fluorescence of thick and thin egg albumens was evaluated as a possible rapid method for the monitoring of egg freshness. The fluorescence emission spectra of tryptophan residues (excitation: 290 nm; emission: 305–430 nm) of proteins and fluorescent Maillard reaction products (excitation: 360; emission: 380–580 nm) were recorded directly on thick and thin albumen samples within 2–3, 4, 5, 9, 10, 12, 16, 18, 23, 25 and 29 days of storage. Principal component analysis (PCA) and factorial discriminant analysis (FDA) were applied to the spectra data sets. Considering tryptophan fluorescence spectra recorded on thick egg albumen, correct classification was observed for 62.8 and 54.3% for the calibration and the validation sets, respectively. Better classification was obtained from thin egg albumen since 67.3 and 69.1% of samples were correctly classified. Considering fluorescent Maillard reaction products, the similarity map determined by the principal components (PCs) 1 and 2 showed a discrimination of eggs as a function of their storage time on both thick and thin albumens. The percentage of samples correctly classified into four groups by the FDA was 97.4 and 91.4% for the calibration and validation thick albumen samples, respectively. It was concluded that fluorescent Maillard reaction products could be considered as fingerprints that may allow the discrimination between fresh and aged eggs.     

The impact of food perishability issues in the vehicle routing problem

Highly perishable food products can lose an important part of their value in the distribution process. We propose a novel multi-objective model that decouples the minimization of the distribution costs from the maximization of the freshness state of the delivered products. The main objective of the work is to examine the relation between distribution scenarios and the cost-freshness trade-off. Small size instances adapted from the vehicle routing problem with time windows are solved with an $∊$-constraint method and for large size instances a multi-objective evolutionary algorithm is implemented. The computational experiments show the conflicting nature of the two objectives.     

Textural and biochemical properties of cobia (Rachycentron canadum) sashimi tenderised with the ultrasonic water bath

The present study investigated the tenderisation effects ultrasound processing (UT) on farmed cobia sashimi. Age-treated cobia trunk muscles (AT) were used as the control. The pH, total volatile base nitrogen, trimethylamine nitrogen, thiobarbituric acid reactive substances, ATP catabolism components, K₁ value, and texture were evaluated. The texture of AT sashimi reached the optimal firmness range with 8.53 N at day 7. However, AT samples could not be served raw after day 7 because of their poor freshness indexes, including a TVBN value of 18.53 g/100 g, a TMAN value of 3.25 mg/100 g, and a TBARS value 0.983 MDA mg/100 g. Moreover, the K₁ value of AT sashimi was 20.21% at day 5. UT was employed to efficiently tenderise cobia sashimi with an initial firmness of 9.70-7.82 N after 90 min of treatment. The results of this study indicate that UT accelerates the biochemical reaction rate, as evidenced by the increases in the TVBN, TMAN, and TBARS contents; however, these values were very low. The results of this study could provide basic information for the development of a novel ultrasonic tenderisation technique in raw seafood designed for restaurants and consumers.     

Fish Quality Index Method: Principles,weaknesses, validation,and alternatives—A review

Fish is a high nutritional value matrix of which production and consumption have been increasing in the last years. Advancements in the efficient evaluation of freshness are essential to optimize the quality assessment, to improve consumer safety, and to reduce raw material losses. Therefore, it is necessary to use rapid, nondestructive, and objective methodologies to evaluate the quality of this matrix. Quality Index Method (QIM) is a tool applied to indicate fish freshness through a sensory evaluation performed by a group of assessors. However, the use of QIM as an official method for quality assessment is limited by the protocol, sampling size, specificities of the species, storage conditions, and assessor's experience, which make this method subjective. Also, QIM may present divergences regarding the development of microorganisms and chemical analysis. In this way, novel quality evaluation methods such as electronic noses, electronic tongues, machine vision system, and colorimetric sensors have been proposed, and novel technologies such as proteomics and mitochondrial analysis have been developed. In this review, the weaknesses of QIM were exposed, and novel methodologies for quality evaluation were presented. The consolidation of these novel methodologies and their use as methods of quality assessment are an alternative to sensory methods, and their understanding enables a more effective fish quality control.     

Postmortem changes in yellow grouper (Epinephelus awoara) fillets stored under vacuum packaging at 0 °C

The freshness of yellow grouper (Epinephelus awoara) stored under vacuum-packing at 0 °C was assessed by physicochemical, sensory and microbiological methods. No significant differences were found in pH and thiobarbituric acid (TBA) values during the storage, while TVB-N, TMA-N, HxR, Hx and K values increased significantly with time. The content of IMP was decreased significantly with the storage time. The texture profile, hardness and chewiness were significantly decreased with the time. L∗ values, the values of chroma and hue were all decreased. However, the increased b∗ values were observed. Furthermore, the significant variations and correlations of sensory attributes were shown with the storage time. A regression analysis for total viable counts yielded a shelf life of 26 days. This suggested that the TMA-N, IMP, HxR, Hx, K value, hardness, chewiness, colour, sensory attributes and microbiological counts may be considered suitable indicators for evaluating yellow grouper fillets spoilage during refrigerated storage.     

臭氧处理对鱼片冷却保鲜效果的研究

本试验采用臭氧水对鱼片进行冷却保鲜,检测冷藏保鲜过程中鱼片的感官、理化、微生物等指标的变化,研究臭氧水对鱼片保鲜的效果。     

Postmortem changes in the adductor muscle of Pacific lions-paw scallop (Nodipecten subnodosus) during ice storage

Postmortem biochemical, chemical, and physical changes of the adductor muscle of Pacific lions-paw scallop were studied during a 15-day storage period at 0 °C (ice). Content of ATP and breakdown products, K value, pH, trimethylamine, total volatile bases, water-holding capacity, colour, and texture changes were examined. K value increased logarithmically (r² = 0.95) from an initial value of 40.3–79.7% on day 15. The spoilage indicators trimethylamine and total volatile bases increased from 15.6 to 30.7 and 1.3 to 6.8 mg N/100 g of sample, respectively, which indicated spoilage at the end of the storage period. Texture, colour, and pH were not affected; however, water-holding capacity decreased significantly, from 96.0% on day 1 to 86.0% on day 15. Overall results indicated that quality of Pacific lions-paw scallop adductor muscle was maintained during at least 12 days of ice storage.     

Freshness Gauge based cold storage management: A method for adjusting temperature and humidity levels for food quality

As the perishable products market grows, the cold chain system is getting more attention. It is desirable for perishable products to keep a good control throughout the whole logistics process. Data collection and the analysis of products are useful for decision making in logistics and it can also enhance the quality of cold chain management. For these reasons, new technologies like Automatic identification and data capture (AIDC) is getting more attention in cold chain management. In this paper, a concept for measuring quality called Freshness Gauge and an algorithm that adjusts proper temperature and humidity levels by reflecting the quality change of eatable products in refrigerated storage are introduced. Shelf-life was used to estimate the food quality and the Centre-of-gravity model and Genetic Algorithm were also applied to get temperature and humidity levels. The proposed algorithms are expected to achieve keeping food quality longer, therefore, the product loss during refrigeration can be reduced.