Fishy Off-flavours Research Articles

Using machine-learning approaches to investigate the volatile-compound fingerprint of fishy off-flavour from beef with enhanced healthful fatty acids

Machine learning classification approaches were used to discriminate a fishy off-flavour identified in beef with health-enhanced fatty acid profiles. The random forest approach outperformed (P < 0.001; receiver operating characteristic curve: 99.8 %, sensitivity: 99.9 % and specificity: 93.7 %) the logistic regression, partial least-squares discrimination analysis and the support vector machine (linear and radial) approaches, correctly classifying 100 % and 82 % of the fishy and non-fishy meat samples, respectively. The random forest algorithm identified 20 volatile compounds responsible for the discrimination of fishy from non-fishy meat samples. Among those, seven volatile compounds (pentadecane, octadecane, γ-dodecalactone, dodecanal, (E,E)-2,4-heptadienal, 2-heptanone, and ethylbenzene) were selected as significant contributors to the fishy off-flavour fingerprint, all being related to lipid oxidation. This fishy off-flavour fingerprint could facilitate the rapid monitoring of beef with enhanced healthy fatty acids to avoid consumer dissatisfaction due to fishy off-flavour.

Flavour Improvement of Protein Hydrolysates Derived from Cephalopods Byproducts Using Maillard Reaction: A Short Review

The conversion of low-value byproducts to high value-added protein hydrolysates by enzymatic hydrolysis is among the top trends in the food industry. Protein hydrolysates provide an opportunity for effective utilization and are considered promising functional food ingredients. However, hydrolyzing effect contributes to taste and aroma defects such as fishy off-flavour and bitterness that impeded their application. Several procedures such as encapsulation, enzymatic hydrolysis with exopeptidase and plastein reaction and Maillard reaction have been compared to mask the undesirable flavour of protein hydrolysates. Maillard reaction has more potential to overcome these challenges and enhance the organoleptic properties of protein hydrolysates. All literature were accessed through available electronic databases. The revised overview can be helpful to explore the rational use of Maillard Reaction with reduced adverse effects. The reaction of Maillard-induced modification on bioactive properties of protein-derived peptides is well-positioned the beneficial effect and facilitate design to obtain applicable functional ingredients for food formulation.

Non-thermal processing of pineapple (Ananas comosus [L.] Merr.) juice using continuous pressure change technology (PCT): HS-SPME-GC–MS profiling, descriptive sensory analysis, and consumer acceptance

The effects of single and twofold continuous pressure change technology (PCT) applications on the volatiles and sensory characteristics of pineapple juice were studied. Fresh and thermally pasteurised juices were additionally characterised. 128 volatiles were tentatively assigned in the four juices. Thermal pasteurisation and a single PCT treatment caused substantial losses in total volatiles of 6 and 20%, respectively. A second PCT passage further reduced the volatiles (36%) and is thus not recommended. PCT-treated samples were clearly distinguished from the remaining juices by principal component analysis. The descriptive sensory profiles, assessed by trained panellists, were not substantially affected by thermal pasteurisation and non-thermal PCT. The fresh juice exhibited a significant fishy off-flavour. In the consumer acceptance test, the thermally pasteurised juice was highly rated compared to both PCT-treated and the fresh juice. This study highlights the potential of PCT to avoid the genesis of off-flavours in fresh-like pineapple juice.

High trimethylamine concentration in milk from cows on standard diets is expressed as fishy off-flavour.

To establish whether fishy off-flavour observed in cows' milk in Sweden is due to abnormal concentrations of trimethylamine (TMA) in milk, 15 milk samples from 13 cows of the Swedish Red and White breed (SRB) were analysed for this compound using dynamic headspace (DHS) gas chromatography (GC). A mass selective detector (MSD) was used for the qualitative and a flame ionization detector (FID) for the quantitative analyses. Further confirmation was obtained using a solid phase microextraction (SPME) followed by GC-olfactometry (GC-O) and GC-NPD (nitrogen and phosphorus detector). Samples were also evaluated by a two-person organoleptic panel for the presence of fishy off-flavour. Results showed that the seven milk samples with a fish-like taint contained > 1 mg TMA/kg milk, whereas, with a single exception, the seven samples that were judged to be normal did not contain this compound. Furthermore, there were indications of a dose-dependent relationship between TMA concentration and fishy off-flavour score.

Effect of incorporation of dietary polyunsaturated fatty acids in pork backfat on the quality of salami

The suitability of backfat high in polyunsaturated fatty acids (PUFA) for salami manufacture was assessed. Eighty pigs (barrows and gilts) were fed four diets, containing 21, 25, 28 and 28 g PUFA/kg feed, originating mainly from soybeans and/or soybean oil in the first three diets and from linseed in the fourth. Salami was prepared with backfat from these pigs, according to gender and dietary treatment. Samples were taken throughout the ripening. The taste panel rejected the two high PUFA (diet 3 and 4) levels; moreover fishy off-flavours were detected for dietary treatment four. Twenty-five grams PUFA/kg feed, corresponding with 23% PUFA in backfat or 15% PUFA in salami, results in acceptable taste, if linoleic acid is the predominant PUFA. However, all PUFA levels resulted in salamis too soft to be commercialized, as evidenced by a fatty film on the salami slicing machine.

Fishy and hay-like off-flavours of dry spinach

Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw spinach: methylpropanal, 2- and 3-methylbutanal and propanal were identified as the odorants with higher odour activity values. It was also found that (Z)-1,5-octadien-3-one and methional, in a concentration ratio of about 1 : 100, are responsible for the fishy off-flavour as dry spinach stored at lower temperatures under nitrogen. The hay-like flavour was caused by oxidative degradation of furan fatty acids, yielding 3-methyl-2,4-nonanedione.

A Chemical Test for Estimating Oily and Fishy Off-Flavour in Bacon

(1954). A Chemical Test for Estimating Oily and Fishy Off-Flavour in Bacon. Acta Agriculturae Scandinavica: Vol. 4, No. 1, pp. 266-271.