TL;DR: To control the more recalcitrant bacteria, several other technologies can be explored including pulsed electric fields, ultrahigh pressure, ultrasound or UV irradiation, and natural products, including bacteriocins and lysozyme.
Abstract: Bacteria are part of the natural microbial ecosystem of wine and play an important role in winemaking by reducing wine acidity and contributing to aroma and flavour. Conversely, they can cause numerous unwelcome wine spoilage problems, which reduce wine quality and value. Lactic acid bacteria, especially Oenococcus oeni, contribute positively to wine sensory characters, but other species, such as Lactobacillus sp. and Pediococcus sp can produce undesirable volatile compounds. Consequences of bacterial wine spoilage include mousy taint, bitterness, geranium notes, volatile acidity, oily and slimy-texture, and overt buttery characters. Management of wine spoilage bacteria can be as simple as manipulating wine acidity or adding sulfur dioxide. However, to control the more recalcitrant bacteria, several other technologies can be explored including pulsed electric fields, ultrahigh pressure, ultrasound or UV irradiation, and natural products, including bacteriocins and lysozyme.
TL;DR: In this paper, combined chemical and sensory methods were used for the source identification of musty off-flavours in water; the methods were based on stripping enrichment, gas chromatography (GC) with both instrumental and sensory detection, and preparative GC.
TL;DR: In this paper, the authors examined water, biofilms in RAS and fillets from cultured arctic charr known to have off-flavours and requiring depuration using instrumental [solid phase microextraction procedure and gas chromatograph mass spectrometry (GC-MS)] and human sensory analyses.
Abstract: The ‘earthy' and ‘muddy' off-flavours in pond-reared fish are due to the presence of geosmin or 2-methylisoborneol in the flesh of the fish. Similar off-flavours have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the cause of these off-flavours. Our hypothesis was that earthy and muddy off-flavour compounds, found previously in pond-raised fish, are also responsible for off-flavours in fish raised in RAS. In this preliminary study, we examined water, biofilms in RAS and fillets from cultured arctic charr known to have off-flavours and requiring depuration using instrumental [solid-phase microextraction procedure and gas chromatograph-mass spectrometry (GC-MS)] and human sensory analyses. Geosmin was present in the samples taken from the biofilter and on the side walls of the tanks. Two-methylisoborneol was only found in low levels in the samples. The GC-MS results indicated the presence of geosmin in the fillets (705 ng kg⁻¹), but lower levels were found in the water (30.5 ng L⁻¹). Sensory analyses also detected an earthy flavour (i.e., geosmin presence) in the fillets, and, therefore, it appears that geosmin is the main compound responsible for the off-flavour in RAS. Further studies are being performed to identify the microorganisms responsible for geosmin production in RAS.
TL;DR: In this paper, the authors discuss the possible origins of off-flavours and taints in foods, and describe some incidents in which food taints have been caused by chemical contamination from the environment.
Abstract: Taints and off-flavours in food are a major cause of consumer rejection of the food product, and consequently the occurrence of such flavour defects is of great concern also to the manufacturer. Unacceptable flavours in foods may develop within the food through chemical or microbial action on food components, or they may be inadvertently introduced into the food during processing or storage, by absorption of chemicals from airborne, waterborne or packaging-related sources. The chemicals responsible for taints and off-flavours are usually volatile organic compounds, which are frequently found at concentrations of less than 1 μg kg -1 , and cause flavour problems because of their low odour-threshold values. This paper discusses the possible origins of off-flavours and taints in foods, and describes some incidents in which food taints have been caused by chemical contamination from the environment.
TL;DR: In this article, the authors found that the highest concentrations of 2,4,6-trichloroanisole in tap water were caused by the formation of 2 4 6 trichlorophenol during chlorine disinfection of drinking water and subsequent methylation of this compound in the distribution system.