Characterization of Volatile Compounds in Chilled Cod (Gadus morhua) Fillets by Gas Chromatography and Detection of Quality Indicators by an Electronic Nose

Abstract

Volatile compounds in cod fillets packed in Styrofoam boxes were analyzed during chilled storage (0.5 degrees C) by gas chromatography (GC)-mass spectrometry and GC-olfactometry to screen potential quality indicators present in concentrations high enough for detection by an electronic nose. Photobacterium phosphoreum dominated the spoilage bacteria on day 12 when the fillets were rejected by sensory analysis. Ketones, mainly 3-hydroxy-2-butanone, were detected in the highest level (33%) at sensory rejection, followed by amines (TMA) (29%), alcohols (15%), acids (4%), aldehydes (3%), and a low level of esters (<1%). The electronic nose's CO sensor showed an increasing response with storage time coinciding with the production of ethanol and 2-methyl-1-propanol that were produced early in the storage, followed by the production of 3-methyl-1-butanol, 3-methyl-butanal, 2,3-butandiol, and ethyl acetate. Lipid-derived aldehydes, like hexanal and decanal, were detected in similar levels throughout the storage time and contributed to the overall sweet odors of cod fillets in combination with other carbonyls (3-hydroxy-2-butanone, acetaldehyde, 2-butanone, 3-pentanone, and 6-methyl-5-heptene-2-one).

Electronic Nose: Current Status and Future Trends

“…Otherwise, differences in new batches caused by, for example, different fishing grounds, the fishing season, the fat content in the flesh, or physical damages due to rough handling and bruising will not be taken into account. 98,99 A very good study about the potential of electronic noses in this field was presented by Olafsdottir et al 100 Using a fundamental approach, the chemical reason for the sensor response of an electronic nose consisting of four electrochemical gas sensors was identified. The experimental setup used included microbial analysis, determination of TVBN, pH measurements, GC/MS measurements, and GC-O measurements.…”

Comparison of olfactometrically detected compounds and aroma properties of four different edible parts of Chinese mitten crab

“…Trimethylamine is a thermal decomposition product of choline, betaine, methionine, or most likely, trimethylamine oxide during cooking [18]. It has been reported as an important odorant in cooked E. sinensis [11], lobster [18], and cod [19] in high concentrations. Due to its high content and intense aroma in this study, trimethylamine could be a net contributor to the aroma of three parts-claw meat, leg meat, and the gonad-of E. sinensis.…”

Characterization of Farmed Ovate Pompano (Trachinotus ovatus Linnaeus) Freshness during Ice Storage by Monitoring the Changes of Volatile Profile

“…1-Penten-3-ol was reported to be the product of the action of lipoxygenases on ω-3 PUFA (German et al, 1992;Hu and Pan, 2000). 1-Penten-3-ol could also be caused by Pseudomonas species and can contribute to the stale and putrid off odors in fish (Miller et al, 1973;Olafsdottir et al, 2005). Nakamura et al (1980) also found that 1-penten-3-ol may be produced by microbial spoilage.…”

“…Heptanal was described to have an earthy and boiled-potato like smell and may cause the fishy odor in cold stored cod (Karahadian and Lindsay, 1989;Olafsdottir et al, 2005;Maqsood and Benjakul, 2011). Heptanal can be used as a reliable indicator of flavor deterioration for fish products, while hexanal is related with the rancidity in meats (Augustin et al, 2006;Ross and Smith, 2006).…”

“…Ethanol and 3-hydroxy-2-Butanone was reported to be associated with the growth of Pseudomonas spp (Olafsdottir et al, 2005). The utilization of carbohydrate sources by spoilage microorganisms caused the production of ethanol.…”