Tilapia fish microbial spoilage monitored by a single optical gas sensor

Abstract

As consumption of fish and fish-based foods increases, non-destructive monitoring of fish freshness also becomes more prominent. Fish products are very perishable and prone to microbiological growth, not always easily detected by organoleptic evaluation. The analysis of the headspace of fish specimens through gas sensing is an interesting approach to monitor fish freshness. Here we report a gas sensing method for monitoring Tilapia fish spoilage based on the application of a single gas sensitive gel material coupled to an optical electronic nose. The optical signals of the sensor and the extent of bacterial growth were followed over time, and results indicated good correlation between the two determinations, which suggests the potential application of this simple and low cost system for Tilapia fish freshness monitoring.

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

“…[ 146,150,160,162 ] Additionally, gas or VOC interactions were also characterized by Fourier‐transform infrared spectroscopy (FTIR) [ 149,160,162 ] or Raman spectroscopy. [ 140 ] Other transduction methods include the use of custom‐made devices, [ 42,94,109,127,142 ] SPR [ 135 ] (used to detect subtle changes in LC birefringence), or quartz crystal microbalance [ 153 ] (used to detect mass changes when chiral LCs were coated on acoustic devices). As discussed in Section 3.6, discotic LCs films exhibit changes in their surface conductivity upon gas exposure.…”

“…The final analysis was performed by converting all images to a gray scale of intensities and their luminosities were subsequently analyzed by Photoshop. Hussain et al, [ 42 ] Semeano et al, [ 142 ] and more recently Esteves et al [ 43 ] used a custom‐made device [ 165 ] where the total intensity of light, generated from a light‐emitting diode and transmitted through crossed polarizers, was converted into an electrical signal by using a light‐dependent resistor. Reyes et al [ 44 ] and Wang et al [ 94 ] detection methods were based on placing the sensing materials between crossed polarizers, allowing for the detection of changes of the transmitted light with the naked eye.…”

“…LC droplets have also been considered as potential candidates for gas sensing applications [ 42,142–145 ] ( Table 4 ). When compared with the solid surface‐based sensing systems described in previous sections, interface‐anchored or (bio)polymeric‐encapsulated LC droplets exhibit a larger surface area, which can be advantageous in chemical sensors designed for higher sensitivity.…”

“…Semeano et al, [ 142 ] Hussain et al, [ 42 ] and recently, Esteves et al [ 43 ] studied self‐assembled LC droplets encapsulated in an ionic liquid interface and dispersed within a biopolymer matrix, overall forming a hybrid gel. The anchoring of 5CB molecules, which is preferentially homeotropic, is promoted by the ionic liquid.…”

Understanding spoilage microbial community and spoilage mechanisms in foods of animal origin

“…For example, Møretrø, Moen, Heir, Hansen, and Langsrud (2016) reported the presence of Pseudomonas in a salmon processing plant before and after sanitation. Seawater can serve as a source of initial contamination and eventual spoilage of seafood in addition to the normal flora present on the fish and in the gastrointestinal tract at the time of harvest (Dousset et al, 2016;Semeano et al, 2018). Other sources of contamination include transportation and storage (Figure 1).…”