Development of a quality index method (QIM) sensory scheme and study of shelf-life of ice-stored blackspot seabream (Pagellus bogaraveo)

Non-Destructive Evaluation of the Physiochemical Properties of Milk Drink Flavored with Date Syrup Utilizing VIS-NIR Spectroscopy and ANN Analysis

A milk drink flavored with date syrup produced at a lab scale level was evaluated. The production process of date syrup involves a sequence of essential unit operations, commencing with the extraction, filtration, and concentration processes from two cultivars: Sukkary and Khlass. Date syrup was then mixed with cow's and camel's milk at four percentages to form a nutritious, natural, sweet, and energy-rich milk drink. The sensory, physical, and chemical characteristics of the milk drinks flavored with date syrup were examined. The objective of this work was to measure the physiochemical properties of date fruits and milk drinks flavored with date syrup, and then to evaluate the physical properties of milk drinks utilizing non-destructive visible-near-infrared spectra (VIS-NIR). The study assessed the characteristics of the milk drink enhanced with date syrup by employing VIS-NIR spectra and utilizing a partial least-square regression (PLSR) and artificial neural network (ANN) analysis. The VIS-NIR spectra proved to be highly effective in estimating the physiochemical attributes of the flavored milk drink. The ANN model outperformed the PLSR model in this context. RMSECV is considered a more reliable indicator of a model's future predictive performance compared to RMSEC, and the R2 value ranged between 0.946 and 0.989. Consequently, non-destructive VIS-NIR technology demonstrates significant promise for accurately predicting and contributing to the entire production process of the product's properties examined.

Nondestructive rainbow trout (Oncorhynchus mykiss) freshness estimation by using an affordable open-ended coaxial technique

In the present work, a nondestructive device set up for a rapid and reliable freshness assessment of rainbow trout during 10 days of storage in ice was evaluated. The device was characterized by a vector network analyzer interfaced with an open coaxial probe to be placed in contact with the fish eye. The acquisition of the reflected scattering parameter (S11), which is the ratio between the amplitude of the reflected and the incident signal, was assessed in the 50 kHz-3 GHz spectral range. S11 is composed of a real part and an imaginary part, and both parts were used to predict quality index method for freshness evaluations. Partial least squares regression predictive models of the demerit scores related to fish eye attributes (eye pupil and eye shape) and the day of storage were set up. The main results showed that both the real and imaginary parts of the S11 decrease as a function of storage time. The combination with multivariate analysis allowed to set up predictive models of the storage time and the demerit scores with R² values up to 0.946 (root mean square error [RMSE] = 0.88 days) and 0.942 (RMSE = 3.17 demerit scores related to the fish eyes attributes), respectively (external validation). According to our results, the proposed cheap solution appears a useful tool for the freshness assessment of rainbow trout. PRACTICAL APPLICATION: This work shows that dielectric properties have the potential to discriminate stored fish according to their freshness quality. A device based on this principle can play a significant role in the postharvest processes, contributing to higher product quality and safety and supporting producers and retailers during the qualitative inspections.

Multivariate Nature of Fish Freshness Evaluation by Consumers

The aim of the present study was to evaluate the sensory acceptability limit of refrigerated fish through a multivariate approach, involving classic physicochemical and bacteriological indicators and considering different consumer profiles. The results of the survival analysis demonstrated that, in general, consumers still considered the fish to be suitable for purchase (4.128 days of storage), despite being microbiologically unsuitable for consumption. However, the subsequent division of consumers into clusters indicated that women and individuals with high income and education levels tend to reject fish with few days of storage (3.650 days), mainly due to discoloration, despite still being microbiologically suitable for consumption. Thus, these segments present a safer behavior regarding the purchase of fresh fish. The influence of different frequencies of fish consumption and age of consumers on the assessment of fish freshness was not clarified. The responsibility for ensuring safe and healthy products at the point of sale must lie with the producers and distributors. However, improving consumers’ ability to make good choices when buying fresh fish would bring social and economic benefits related to public health and to the seafood industry, because it would enable them to make relevant claims and demand their rights.

Texture changes during chilled storage of wild and farmed blackspot seabream (Pagellus bogaraveo) fed different diets

The impact of changes in dietary lipids and protein sources on texture was evaluated on farmed blackspot seabream (Pagellus bogaraveo) throughout 14 days of ice storage and compared with wild fish. A commercial diet formulated with a high proportion of lipids, and two diets formulated with an important reduction of lipid levels by 60% and adding either plant protein sources (LL diet) or fishmeal (LL + diet) were supplied during growth until commercial size was attained. In the wild fish, the raw fillet hardness was significantly higher than in farmed fish during the entire ice-storage period. In the farmed fish, an increase of muscle lipid accumulation and change of fiber density were responsible for the variations in texture in the raw fillet. The highest reduction was found in fish fed with diets LL+ and LL. The texture parameters studied on the cooked fillets showed no significant differences, neither attributable to the diets nor to the ice-storage period.

Estimating freshness of ice storage rainbow trout using bioelectrical impedance analysis

This study aimed to evaluate the freshness of ice stored rainbow trout by bioelectrical impedance measurements. Rigor mortis, ATP-related components, K-value, and hardness of rainbow trout muscle during storage were monitored along with impedance. The results showed that the progress of rigor mortis was accompanied by an increase in impedance. Impedance kept decreasing even in rigor state, and during the gradual resolution of rigor mortis with impedance change upon storage of fish was biphasic (r = -0.944, p < .01). Thus, when impedance decreased close to the lowest value, K-value was only about 61.57 ± 0.52%, but still exhibited a high pertinence (r = -0.959, p < .01). A gradual decrease of the hardness of fish muscle upon storage of fish showed a close correlation (r = 0.981, p < .01) with impedance decrease. These results suggested that the impedance measurement has a great potential for predicting the freshness of the rainbow trout during ice storage.

Nanoencapsulated Clove Oil Applied as an Anesthetic at Slaughtering Decreases Stress, Extends the Freshness, and Lengthens Shelf Life of Cultured Fish

In the aquaculture industry, fish are stunned using a wide range of methods, but all of them trigger stress responses and affect the fish flesh quality. Chilled water is considered one of the most efficient methods, but even this is not a stress-free experience for the fish. Anesthetics included in the ice slurry or in water could decrease this stress and delay the loss of flesh quality. In this work, we analyze the effect of clove oil (CO) nanoencapsulated in β-cyclodextrins (β-CD) (CO + β-CD), incorporated in the stunning bath, on the stress response and the organoleptic attributes of fresh marine and freshwater fish from four economically important fish species: Atlantic salmon, European seabass, Nile tilapia, and Rainbow trout. CO + β-CD reduces the time required to induce anesthesia, independently of water salinity, habitat or water temperature. The plasmatic glucose and cortisol levels decreased in all four species, although the concentrations of CO varied between species. Moreover, plasmatic lactate level differed between the marine and freshwater fish. The use of CO + β-CD extended the shelf life of fish from all the species studied (by 3-7 days). In conclusion, using CO encapsulated in β-CD for anesthetizing fish can be regarded as an improved fish-stunning technique that reduces the anesthesia-induction time, decreases the stress response, and extends the shelf life of fresh fish.

Effects of ε-polylysine and rosemary extract on the quality of large yellow croaker (Pseudosciaena crocea) stored on ice at 4 ± 1°C

To evaluate the quality changes in large yellow croaker (Pseudosciaena crocea) with ε-polylysine and rosemary extract stored on ice at 4 ± 1°C. About 0.1% ε-polylysine (PL) and 0.2% rosemary extract (RE) were individually or in combination with each other were treated with samples. Samples treated with deionized water were regarded as control check (CK) group. Physicochemical (texture profile analysis (TPA), pH, total volatile basis nitrogen (TVB-N), thiobarbituric acid (TBA)), endogenous enzyme activity (cathepsin B and D), proteolytic degradation (Trichloroacetic Acid (TCA)-soluble peptides and Sodium Salt-polyacrylamide gel electrophoresis (SDS-PAGE)), microbiological (Total viable count (TVC), Shewanella bacteria count, Pseudomonas bacteria count, Psychrophilic bacteria count) and sensory evaluation were conducted during the whole storage. As a result, PL + RE could delay the increase in pH, TVB-N, TBA value, and improve the texture attributes compared with the CK group. In addition, PL + RE could inhibit cathepsin B and D activities, protein degradation, and microbial growth effectively. Moreover, the shelf life of samples could be prolonged at least 4 days when compared with the CK group according to the quality index method (QIM) and physicochemical assay, indicating that the PL + RE treatment could maintain the quality of large yellow croaker more effectively. PRACTICAL APPLICATIONS: The preservation of fish is becoming increasingly important in aquatic products. According to the fence theory, a combination of biopreservatives with different functions could be used to maintain the freshness synergistically. Furthermore, this research indicates that the combination of ε-polylysine and rosemary extract, a promising method for the preservation of aquatic products, could slow down the deterioration of large yellow croaker and prolong its shelf life.

A Systematic AQbD Approach for Optimization of the Most Influential Experimental Parameters on Analysis of Fish Spoilage-Related Volatile Amines

The volatile amines trimethylamine (TMA) and dimethylamine (DMA) could be used as important spoilage indices for seafood products, assisting in the determination of the rejection period. In the present study, a systematic analytical duality-by-design (AQbD) approach was used as a powerful strategy to optimize the most important experimental parameters of headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) conditions for the quantification of TMA and DMA in Sparus aurata. This optimization enabled the selection of the best points in the method operable design region for HS-SPME extraction (30 min; 35 °C; NaOH 15 M and NaCl 35%, w/v) and GC-MS analysis (80 °C; gradient 50 °C/min; flow rate 1 mL/min and splitless mode). The rejection day, estimated through the TMA concentration (>12 mg/100 g, at days 9–10), was compared with sensory (quality index method: day 7–8), physical (Torrymeter: day 8–9), and microbial (day 9–10) analysis, corroborating the suitability of the proposed approach for estimating the period for which they will retain an acceptable level of eating quality from a safety and sensory perspective.

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.

Freshness Assessment and Shelf-Life Prediction for Seriola dumerili from Aquaculture Based on the Quality Index Method

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.

Quality evaluation of fish and other seafood by traditional and nondestructive instrumental methods: Advantages and limitations

Although being one of the most vulnerable and perishable products, fish and other seafoods provide a wide range of health-promoting compounds. Recently, the growing interest of consumers in food quality and safety issues has contributed to the increasing demand for sensitive and rapid analytical technologies. Several traditional physicochemical, textural, sensory, and electrical methods have been used to evaluate freshness and authentication of fish and other seafood products. Despite the importance of these standard methods, they are expensive and time-consuming, and often susceptible to large sources of variation. Recently, spectroscopic methods and other emerging techniques have shown great potential due to speed of analysis, minimal sample preparation, high repeatability, low cost, and, most of all, the fact that these techniques are noninvasive and nondestructive and, therefore, could be applied to any online monitoring system. This review describes firstly and briefly the basic principles of multivariate data analysis, followed by the most commonly traditional methods used for the determination of the freshness and authenticity of fish and other seafood products. A special focus is put on the use of rapid and nondestructive techniques (spectroscopic techniques and instrumental sensors) to address several issues related to the quality of these products. Moreover, the advantages and limitations of each technique are reviewed and some perspectives are also given.

Microbiological evolution of gilthead sea bream (Sparus aurata) in Canary Islands during ice storage

This study analyses the microbiological changes with traditional methods for total mesophilic aerobic, psychrotrophic, Aeromonas sp., Pseudomonas sp., Shewanella putrefaciens, Enterobacteriaceae, sulfide-reducing Clostridium and Photobacterium phosphoreum in muscle, skin and gills of whole ungutted gilthead sea bream (Sparus aurata) stored in ice during 18 days. The muscle tissue showed the minor grade of contamination, followed by the skin and the gills, with statistic significance (p < 0.001). The most prominent microorganisms in the different tissues and at the end of the storage were Pseudomonas sp. (7.76, 10.11 and 10.40 log CFU/g), Aeromonas sp. (7.49, 8.24 and 9.02 log CFU/g) and S. putrefaciens (8.05, 7.49 and 8.05 log CFU/g) in sea bream harvested in the temperate water of the Canary Islands. The results obtained from this study can contribute to the improvement of microbiological knowledge of gilthead sea bream (Sparus aurata) by determining the evolution of microorganisms responsible for spoilage and their counts in different tissues such as muscle, skin, and gills during iced storage.