Spatially Offset Raman Spectroscopy Combined with Attention-Based LSTM for Freshness Evaluation of Shrimp

Optical detection of the freshness of intact in-shell shrimps is a well-known difficult task due to shell occlusion and its signal interference. The spatially offset Raman spectroscopy (SORS) is a workable technical solution for identifying and extracting subsurface shrimp meat information by collecting Raman scattering images at different distances from the offset laser incidence point. However, the SORS technology still suffers from physical information loss, difficulties in determining the optimum offset distance, and human operational errors. Thus, this paper presents a shrimp freshness detection method using spatially offset Raman spectroscopy combined with a targeted attention-based long short-term memory network (attention-based LSTM). The proposed attention-based LSTM model uses the LSTM module to extract physical and chemical composition information of tissue, weight the output of each module by an attention mechanism, and come together as a fully connected (FC) module for feature fusion and storage dates prediction. Modeling predictions by collecting Raman scattering images of 100 shrimps within 7 days. The R², RMSE, and RPD of the attention-based LSTM model achieved 0.93, 0.48, and 4.06, respectively, which is superior to the conventional machine learning algorithm with manual selection of the optimal spatially offset distance. This method of automatically extracting information from SORS data by Attention-based LSTM eliminates human error and enables fast and non-destructive quality inspection of in-shell shrimp.

Combining Knowledge- and Data-Driven Fuzzy Approach to Evaluate Shelf-Life of Various Seafood Products

Due to the complexity of the deterioration process of seafood products, relying on one indicator is not adequate to determine the quality of such products. Usually, shelf-life was estimated based on various indicators complicating the decision-making process. Decision Support Systems are considered as a good solution. The current study aims to establish a simple and novel fuzzy model based on a combination of knowledge- and data-driven approaches to define a fuzzy quality deterioration index (FQDI) in various seafood products (rainbow trout, threadfin bream, and white shrimp samples) during cold storage. Total volatile basic nitrogen (TVB-N) and psychrotrophic microorganisms counts (PMCs) were determined based on traditional methods. The sensory analysis was performed by a data-driven fuzzy approach. Overall, the shelf-life of the rainbow trout fillet was estimated to be 8 days, based on all the freshness parameters. However, the shelf-life of the Japanese threadfin bream fillet was 5–7 days according to the microbial and chemical parameters, respectively. This time for shrimp samples was 6–8 days using sensory score and TVB-N contents. The results of data-driven fuzzy approach showed all of the quality properties were considered as the ‘Important’–‘Very Important’ (defuzzification score >75). The TVB-N and PMCs were the most and weakest freshness quality properties (defuzzified-values: 84.64 and 78.75, respectively). Based on FQDI, the shelf-life of the rainbow trout, Japanese threadfin bream, and shrimp samples were estimated to be 8, 5, and 7 days, respectively. This method was able to successfully provide a comprehensive deterioration index for evaluating the seafood shelf-life. Such a total index can be considered as a comprehensive output (y variable) to predict seafood freshness by rapid and nondestructive method.

Antibacterial effects of extracted corn zein with garlic extract-based nanoemulsion on the shelf life of Vannamei prawn (Litopenaeus vannamei) at refrigerated temperature

BACKGROUND

Litopenaeus vannamei is one of the most perishable foods due to microorganism growth. Using essential oil-based nanoemulsion as a biodegradable and edible coating can enhance the shelf life of shrimp at refrigerated temperature through retarding microbial growth compared to synthetic coatings.

METHODS

Zein was extracted from 50 g dry milled corn with ethanol. Garlic essential oil was prepared by mixing with Tween 80. Nanoemulsion was prepared in an ultrasonic bath. DLS analysis, turbidity, and stability of nanoemulsions were performed. Radical scavenging activity, and total phenol content were done for evaluation of garlic essential oil and nanoemulsion. A 10% zein solution was prepared using ethanol 95% and glycerol plasticizer (2.5%). In the end, various microbial analysis, peroxide value, the thiobarbituric acid reactive substance (TBARS) value, the total volatile basic nitrogen (TVB-N) values, and sensory evaluations of different shrimp samples were determined.

RESULTS

Corn zein along with garlic-based nanoemulsion, had a great impact on the TVB-N, TBARS, and peroxide value (which indicated that z+24% garlic nanoemulsion group was the lowest among other groups on days 3, 7, and 14 (p < 0.05) as well as microbial properties (garlic EO nanoemulsion had significantly better antibacterial effectiveness compared to other groups (p < 0.05)), and sensory evaluation (the z+24% garlic nanoemulsion sample received a significantly higher score than other groups (p < 0.05)) of Litopenaeus vannamei.

CONCLUSIONS

Corn zein nanoemulsion functioned as an antioxidant and antimicrobial agent, increasing the shelf life of Litopenaeus vannamei at refrigerated temperature.

PRACTICAL APPLICATION

Emerging nanotechnology-based approaches with no side-effects on immune system of consumers plays a vital role in bioactive packaging, and on reduction of food spoilage or food poisoning in the transportation, exporting, and distribution stages of food products, especially marine-based products with cold chain transportation. Additionally, it can reduce aquaculture and environmental risks due to the usage of chemical agents used in packaging. Our results showed that administration of a corn zein with nanoemulsion of garlic extract can prolong shelf life of Litopenaeus vannamei. The paper should be of interest to readers such as food microbiologists, aquaculture scientists, fisheries scientists, marine biologists, biomaterial scientists, food packaging industrialists, medical microbiologists, public health managers, and health system managers.

Effect of low-temperature preservation on quality changes in Pacific white shrimp, Litopenaeus vannamei: a review

Shrimp has been widely accepted as an excellent resource for white meat due to its high-protein and low-fat content, especially low cholesterol. However, shrimps are highly perishable during preservation and retailing procedures due to the activities of enzymatic proteolysis, lipid oxidation, and microbial degradation. With increasing knowledge of and demands for safety, nutrition, and freshness of shrimp products, energy efficient, quality, maintained, and sustainable preservation technologies are needed. Low-temperature preservation, a practical processing method for improving the shelf life of food products, is widely used in the aquatic industry. This review focuses on the effects of low-temperature preservation on the quality changes in Litopenaeus vannamei. It considers physicochemical properties, sensory evaluation, melanosis assessment, and microbiological analysis. The perspectives of non-protein-based techniques on quality analysis of shrimps during preservation are also discussed. © 2019 Society of Chemical Industry.

Effects of different ozonized slurry-ice treatments and superchilling storage (-1°C) on microbial spoilage of two important pelagic fish species

Combining different preservative treatments for improving quality and safety of fishery products increasingly receives global research attention. Consistent with this pursuit, the current research was undertaken to determine the effects of different ozonized slurry-ice treatments and superchilling (-1°C) storage on microbial spoilage of European anchovy (Eugraulis encrasicolus) and sardine (Sardina pilchardus), which are two commercially important pelagic fish species. After the catch (within <5 hr) and at defined scheduled storage times, ozone has been discharged once on sardine (herein referred to as "One-T") and repeatedly/sequentially on European anchovy (herein referred to as "Seq-T"). Microbiological analyses enumerated total viable count (TVC), Bacillus spp., Enterobacteriaceae, Lactobacillus spp., Moraxella spp., Shewanella spp., Listeria monocytogenes and Pseudomonas spp. Independent of potential antimicrobial effects of ozone during superchilling storage, no Listeria spp., Shewanella spp., Moraxella spp., and Bacillus spp. were found in all processed samples. While Enterobacteriaceae and Lactobacillus spp. were detected at below 1 log cfu/g, both TVC and Pseudomonas spp. proliferated at different rates throughout superchilling storage. The repeated ozone-treated ("Seq-T") showed lower TVC and Pseudomonas spp. values compared with one-time treated ("One-T") slurry-iced and control samples. Thus, combined slurry-ice and superchilling storage at Seq-T produced improved antimicrobial activity over One-T application. Largely, ozonized slurry-ice outcomes/results appear promising thanks to superchilling storage.