Organoleptic Defects Research Articles

Ethyl esters versus fermentative organoleptic defects in virgin olive oil.

The quality and genuineness of extra-virgin olive oils (EVOOs) were assessed following the methods and parameters of EU Commission Regulation N° 2568/91/EEC and subsequent modifications, which also set specific limits for fatty-acid ethyl esters (FAEEs). This study included a subset of EVOOs from among 399 samples analysed as part of a monitoring study for FAEEs in EVOOs. The subset was subjected to statistical evaluation to quantify the relationships between FAEE content and sensory defects associated with fermentation: fusty/muddy sediment, musty/humid/earthy, and winey/vinegary. The use of multiple regression analysis demonstrates that FAEE content can be inferred as a function of the intensity of organoleptic defects for samples with high alkyl esters content. The intensity of the rancid defect negatively influences the accuracy of this model, because of underestimation of the fermentation defects that are also present.

Fatty-acid alkyl esters in table olives in relation to abnormal fermentation and poorly conducted technological treatments

There are several methods to prepare table olives, and each of the steps and conditions during this processing can affect the composition and nutritional value of the product. The influence of abnormal fermentation and poorly conducted technological treatments was examined here in terms of the lipid fraction of table olives. In ‘Greek style’ olives, a low concentration of brine can allow the growth of spontaneous microflora and consequent organoleptic defects (‘putrid/butyric fermentation’, ‘winey-vinegary’). Here, the ‘Kalamata’ and ‘Moresca’ cultivars can produce methyl esters (methyl oleate/ linoleate: 553 and 450 mg·kg -1 oil, respectively) and ethyl esters (ethyl oleate/ inoleate: 4764 and 4195; palmitate: 617 and 886 mg·kg -1 oil, respectively). In ‘Sevillan style’ olives, a high NaOH concentration influences the fatty-acid composition less, but is difficult to eliminate, for a ‘soapy’ defect. The ‘Giarraffa’ and ‘Nocellara del Belice’ cultivars produce only ethyl esters (ethyl oleate/ linoleate: 222 and 289 mg·kg -1 oil, respectively). With this production of ethyl and methyl esters from the principal fatty acids in the lipid fractions of table olives, methods that provide only biological treatments (i.e., Greek style) pose more risk than methods that provide only chemical treatments (i.e., Sevillan style).

Use of non-conventional yeast improves the wine aroma profile of Ribolla Gialla.

Consumer wine preferences are changing rapidly towards exotic flavours and tastes. In this work, we tested five non-conventional yeast strains for their potential to improve Ribolla Gialla wine quality. These strains were previously selected from numerous yeasts interesting as food production candidates. Sequential fermentation of Ribolla Gialla grape juice with the addition of the Saccharomyces cerevisiae T73 Lalvin industrial strain was performed. Zygosaccharomyces kombuchaensis CBS8849 and Kazachstania gamospora CBS10400 demonstrated positive organoleptic properties and suitable fermentation dynamics, rapid sugar consumption and industrial strain compatibility. At the same time, Torulaspora microellipsoides CBS6641, Dekkera bruxellensis CBS2796 and Dekkera anomala CBS77 were unsuitable for wine production because of poor fermentation dynamics, inefficient sugar consumption and ethanol production levels and major organoleptic defects. Thus, we selected strains of K. gamospora and Z. kombuchaensis that significantly improved the usually plain taste of Ribolla wine by providing additional aromatic complexity in a controlled and reproducible manner.

The interaction between starch hydrolysis and acidification kinetic determines the quality of a malted and fermented sorghum beverage

Gowé is a traditional fermented Beninese soft cooked paste made from a blend of malted and non-malted cereals that is diluted with water/ice and sugar just before consumption as a thirst-quenching drink. Major differences in the processes used for the preparation of gowé, which includes natural lactic fermentation, result in variable quality. Acidity and free sugar content have been linked to the process parameters but also to the type of strains that can be used for inoculation. The aim of this study was to investigate the starch degradation mechanism in relation with the activity of degrading enzymes during the preparation of gowé and enzyme impact on the quality (sugar content and viscosity) of the final product. Our results point to a key role for malt α-amylase and its susceptibility to acidic conditions in the sequence of the preparation process and in the final quality of gowé. Pre-cooking and inoculation speeds up and increases acidification of the product thereby favoring its safety, but reduces the final free sugar content and increases the final viscosity of gowé, which are both organoleptic defects of the product.

The problem of 2,4,6-trichloroanisole in cork planks studied by attenuated total reflection infrared spectroscopy: proof of concept.

Attenuated total reflection infrared spectroscopy (ATR-IR) proved to be a promising detection technique for 2,4,6-trichloroanisole (TCA), which confers organoleptic defects to bottled alcoholic beverages, allowing the proposal of a criterion for cork plank acceptance when meant for stopper production. By analysis of a significant number of samples, it was proved that the presence of TCA, even in very low concentrations, imparts subtle changes to the cork spectra, namely, the growth of two new bands at ∼1417 (νC═C of TCA ring) and 1314 cm–1 (a shifted νCC of TCA) and an increase in the relative intensities of the bands at ∼1039 cm–1 (δCO of polysaccharides) and ∼813 cm–1 (τCH of suberin), the latter by overlapping with intense bands of TCA. These relative intensities were evaluated in comparison to a fingerprint of suberin (νasC–O–C), at 1161 cm–1. On the basis of those spectral variables, a multivariate statistics linear analysis (LDA) was performed to obtain a discriminant function that allows classifying the samples according to whether they contain or not TCA. The methodology proposed consists of a demanding acceptance criterion for cork planks destined for stopper production (with the guarantee of nonexistence of TCA) that results from combining the quantitative results with the absence of the two TCA correlated bands. ATR infrared spectroscopy is a nondestructive and easy to apply technique, both on cork planks and on stoppers, and has proven more restrictive than other techniques used in the cork industry that analyze the cleaning solutions. At the level of proof of concept, the method here proposed is appealing for high-value stopper applications.

Analysis of grapes and the first stages of the vinification process in wine contamination with Brettanomyces bruxellensis

Brettanomyces bruxellensis is a major cause of wine spoilage due to the production of ethyl phenols, and it has become a major worldwide oenological concern in recent years. The most critical factor in volatile phenol production is the presence of microorganisms responsible for biosynthesis. In this work, carried out during three consecutive harvests, grapes and the first step in grape processing (stemming–crushing) have been evaluated as the origin of wine contamination by these spoilage yeasts. Results showed that there was nil or minimal presence of Brettanomyces yeasts in grapes and on the stemmer, in levels that the method was not able to detect. This shows that the main contamination of wines by this microorganism occurs in later stages of the vinification process and/or during storage. The contamination of many wines with Brettanomyces, either via the fruit or from the winery environment, during the early stages of vinification and before the start of aging, was confirmed by analyzing 100 recently made red wines, in which this yeast was detected in a high percentage of wines (27 %). However, the level of Brettanomyces yeasts found in the samples was low, with values which would not be sufficient to cause organoleptic defects. Consequently, this study confirms that many wines are still tainted by Brettanomyces when the winemaking phase comes to an end. It was also found that wines with problems during fermentation had a higher level of Brettanomyces. This is why it is essential to ensure strict controls during fermentation processes and conservation to prevent wine becoming spoiled or tainted.

Fatty acid alkyl esters presence in olive oil vs. organoleptic assessment

The scientific work on the authenticity and quality of olive oil is an ever-growing area. Olive oil genuineness is not only valuable for the producers, but also for the consumers who expect an actual correspondence between the products they purchase and the information on the packaging labels.Sometimes oil’s rejection by consumers is just a matter of taste, sometimes is a more objective question. Low quality olive oils with weak organoleptic defects are the targets of illegal blends that can be detected by determining the content of fatty acid alkyl esters (FAAEs). In this line we have established a relationship between the FAAEs concentration of olive oils and their sensory classification. Besides, a connection between the presence of large quantities of FAAEs and fermentative organoleptic defects has been proven.

(−)Geosmin sorption by enological yeasts in model wine and FTIR spectroscopy characterization of the sorbent

For the first time, we report that enological yeasts or yeast cell walls can sorb (−)geosmin, an undesirable molecule that causes critical organoleptic defects in wine at low concentrations (around 50 ng l −1). The wine is described as “earthy” or “mouldy”. The influence of various post-harvesting processes on yeast (−)geosmin sorption capacity was studied. The dried yeast biomass obtained by the different processes was analysed by FTIR spectroscopy in ATR mode: structural differences were detected between the samples depending on the strain and the treatment used. Surface proteins and mainly phospholipids from the plasma membrane appeared to induce significantly different signals which may explain the different sorption capacities. The possible involvement of phospholipids in (−)geosmin sorption by yeasts highlights the complexity of this phenomenon. The post-harvesting processes were: spray-drying, mechanical cell disruption, autolysis and two methods of rehydration of dried yeast samples. The results show that, using the optimal combination of processes, the initial (−)geosmin concentration in model wine can be decreased by more than 50%.

Rapid headspace solid-phase microextraction/gas chromatographic/mass spectrometric assay for the quantitative determination of some of the main odorants causing off-flavours in wine

In this study we present a rapid and simultaneous assay method using headspace (HS) solid-phase microextraction (SPME)/gas chromatography (GC)/electron impact (EI) mass spectrometry (MS) (selected ion monitoring) for contaminants causing the principal organoleptic defects of wine (2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole, pentachloroanisole, 2,4,6-tribromoanisole, 1-octen-3-ol, geosmin, 2-methylisoborneol, 3-isopropyl-2-methoxypyrazine, fenchol, fenchone, 2-methoxy-3,5-dimethylpyrazine, 4-ethylphenol, 4-ethylguaiacol, 4-vinylphenol, 4-vinylguaiacol, 3-isobutyl-2-methoxypyrazine, guaiacol and ethyl acetate). The method was validated according to protocols NF ISO 5725-1, 2 and NF V03-110. Its characteristics (limit of detection (LOD), limit of quantification (LOQ), uncertainties) were determined after having optimised the SPME parameters. The target contaminants were quantified in the wines below their threshold of perception with a satisfactory relative standard deviation for all the analytes except ethyl acetate (RSD = 36%); for that, the assay method permits clear differentiation of the wines that are at risk of presenting an acescent character, i.e. containing more than 120 mg L −1 ethyl acetate. The target volatile and odorous substances were determined at concentrations significantly below their threshold of perception in a hydroalcoholic context and their threshold of recovery in wines.

Characterization of Some Mushroom and Earthy Off-Odors Microbially Induced by the Development of Rot on Grapes

Grape rot is one of the major causes of degradation of many grape components and, thus, of deterioration in wine quality. In particular, the association of Botrytis cinerea with other, less visible, fungi frequently leads to the development of organoleptic defects in grapes and sometimes in wines. This study examines the nature of the volatile compounds responsible for mushroom, mossy, or earthy odors detected by gas chromatography-olfactometry in organic extracts of rotten grapes and musts. 2-Methylisoborneol, (-)-geosmin, 1-octen-3-one, 1-octen-3-ol, 2-octen-1-ol, and 2-heptanol were identified or tentatively identified. Their concentrations in musts were determined, and the impact of alcoholic fermentation by the yeast Saccharomyces cerevisiae was studied. The ability of fungi isolated from rotten grapes (Botrytis cinerea; Penicillium species including P. brevicompactum, P. expansum, P. miczynskii, P. pinophilum, P. purpurogenum, and P. thomii; Aspergillus section nigri; Rhizopus nigricans; and Coniothyrium sp.) to produce some of the identified compounds was evidenced.

Industrial implementation of black ripe olive storage under acid conditions

Restrictions on the discharge of chloride in wastewater streams have recently increased, and processors of black ripe olives have to look for alternative storage systems to the traditional brines. Ripe olives of the Hojiblanca variety were stored under aerobic and anaerobic conditions in industrial underground tanks for one year. The aerobic systems assayed with or without NaCl produced a continuous consumption of sugars as they diffused from the fruits to the surrounding liquid. At the same time sugars accumulated in the liquid for months when anaerobic conditions were employed and a high concentration of acetic acid was used. In the end, glucose was consumed with time as well and, in addition to yeasts, acetic acid and lactic acid bacteria grew in the cover solutions. The assessment of olives stored under the different systems and processed as black ripe olives revealed that the traditional aerobic brines gave rise to darker and firmer fruits. However, olive industries must eliminate chlorides from their waste streams. Promising new storage systems were (i) anaerobic preservation of olives in water with an initially high concentration of acetic acid, and (ii) aerobic preservation in water with an initially low concentration of acetic acid. Both systems produced a good quality product, free of microbial spoilage and organoleptic defects.

The relationship between quality criteria of goat milk, its technological properties and the quality of the final products

This paper presents the main criteria that enable the control of milk quality criteria that are included in a payment system based on goat milk quality, with regard to hygienic quality and the technological and sensorial impacts on the final products. Somatic cells, often linked to mastitis and thus to pathogens when the count is high, induce changes of the biochemical composition of milk. However, somatic cell count (SCC) does not seem to impair either cheese-making or sensorial characteristics of the cheeses for SSC close to 1,800,000 cells/ml. Some problems could, nevertheless, occur for the production of high heat-treated milks. The presence of colostrum (IgG) could impair heat-treated fluid milk production, while inhibiting substances could impair the fermentation process. Taking into account the great variability of natural inhibiting substances contained in goat milk, the bovine test applied to goat milk should be adapted. Bacteria count gives a good estimation of the hygienic quality of milk and although pathogens are also included in payment systems, these are not discussed. Nevertheless, different classes of bacteria should be distinguished due to the specific character or change each may cause, for example, psychrotrophic bacteria, which may produce heat resistant protease and lipase and induce organoleptic defects in goat milk products. The fat and protein contents in goat milk have been improved through genetics and feeding programmes. Protein percentage, however, is not a precise criterion to predict and ensure cheese yield. Casein percentage would be a more precise criterion to ensure cheese yield. The lipolysis of goat milk can be a useful optional criterion to ensure the quality of non-ripened lactic cheeses.

Identification of 9(E),11(E)-18:2 Fatty Acid Methyl Ester at Trace Level in Thermal Stressed Olive Oils by GC Coupled to Acetonitrile CI-MS and CI-MS/MS, a Possible Marker for Adulteration by Addition of Deodorized Olive Oil

The olive oil market is suffering from sophisticated illegal treatments. One common adulteration process consists of the addition to virgin olive oil of lower quality oils, such as "lampante" oil, an inexpensive oil and with some organoleptic defects, which is then submitted to thermal deodorization under vacuum processes for removal of the undesired flavor components. Such a blending may not have a huge influence on the chemical composition and may not significantly affect the parameters usually checked as quality indicators, although the organoleptic properties may change. As a consequence, a major effort is being devoted to find reliable markers able to unmask such adulterations. We report here the complete characterization of a compound, detected at trace levels exclusively in thermal stressed oils, which could be a candidate marker for adulteration. The investigation, carried out by GC-MS and GC-MS/MS, provided its complete structure, including the stereochemistry, shown to be a 9(E),11(E)-18:2 fatty acid methyl ester. Experimental data also confirmed the influence of both temperature and heating time on formation and concentration of this compound.

Sorption of wine volatile phenols by yeast lees

The capacity of Saccharomyces cerevisiae yeast lees to sorb 4-ethylguaiacol and 4-ethylphenol was investigated in a synthetic medium and in wine. Active dried yeast was more effective when volatile phenols were diluted in red wine. Partition coefficients between wine model solution and wine yeast lees were determined and compared with those measured for dried active yeast. They showed a larger affinity of volatile phenols for wine yeast lees than for dried active yeast. The effect of yeast lees on volatile phenol sorption was sensitive to yeast autolysis level and to physicochemical parameters, such as ethanol content, temperature and pH. These results could be applied in the technology of reduction of organoleptic defects in wine due to phenols.

Lien entre le niveau de lipolyse du lait de chèvre et la qualité sensorielle des fromages au lait cru ou pasteurisé

Link between goat milk lipolysis and sensorial quality of lactic goat cheeses made from raw or pasteurised milk. There is an important variability of the lipolysis level in goat milk, due to various physiological and breeding factors. The aim of this study was to evaluate the impact of these natural variations on the sensorial quality of fresh and ripened lactic goat cheeses. The effect of milk pasteurisation was also studied. The results show that the variation of the lipolysis level of goat milk do not have any significant effect on the sensorial quality of ripened cheeses. On the contrary, the sensorial quality of fresh cheeses is linked to the lipolysis level of milk. These results allowed us to recommend some means of controlling the sensorial quality of goat cheeses. For ripened cheeses, a satisfying sensorial quality could be obtained via the control of the technological parameters, notably the moisture in non-fat cheese at the demoulding. For fresh cheeses, the lipolysis level of milk should be checked before cheesemaking, and milks with high lipolysis levels should not be used. Pasteurisation of milk induced a decrease in the lipolysis level of cheeses. The use of pasteurisation led to a limitation of the appearance of organoleptic defects in rip- ened cheeses, but the overall flavour and odour of ripened cheeses made from pasteurised milk was also reduced compared to cheeses made from raw milk. goat milk / lipolysis / goat cheese / sensorial quality / pasteurisation

A numerical taxonomic study of the Pseudomonas flora isolated from poultry meat.

Pseudomonas strains were isolated from both fresh and cold-stored broiler skin. Phenotypically-based numerical taxonomic techniques were used to characterize the isolates and 36 reference strains. For this purpose, Biolog GN Microplates, API 20NE and a number of other biochemical tests were used. Jaccard clustering revealed the predominance of four major Pseudomonas groups: Ps. fragi, Ps. lundensis, strains belonging to Ps. fluorescens biovars and an unidentified group of strains displaying a high degree of similarity to Ps. fluorescens biovars. Within Ps. fluorescens, biovar A was best represented. The marked proteolytic character of members of Ps. fluorescens biovars A, B and C, as well as of members of the unidentified cluster, supports their possible role in the origin of organoleptic defects. In the Ps. lundensis cluster, a distinct group of Ps. lundensis-like species was found. Further genotypic studies should be carried out to clarify the taxonomic status of the Ps. lundensis-like strains and that of the unidentified group resembling Ps. fluorescens biovars A and B.

Deacidification of red and white wines by a mutant of Schizosaccharomyces malidevoransunder commercial winemaking conditions

A mutant of Schizosaccharomyces malidevorans, which utilizes malic acid more rapidly than the wild-type strain and does not utilize significant amounts of glucose or fructose, was used in commercial scale deacidification of grape juice during two vintages in a New Zealand winery. Four trials were conducted in Chardonnay, Semillon and Cabernet Sauvignon juices, 1000–4500 l. In the first two trials, the juices were inoculated with the alcoholic fermentation yeast, Saccharomyces cerevisiae, 33–48 h after the mutant inoculation. In the remaining two trials, the juices were inoculated simultaneously with the mutant and S. cerevisiae. Malic acid, ranging from 3.5–10 g l −1in the juices, was completely degraded within 21–73 h. The Schiz. malidevoransmutant utilized malic acid at sulfur dioxide levels and temperatures used in red and white winemaking. The wines produced in the trials lacked obvious organoleptic defects. They were blended with untreated wines for acid balance and retailed as varietal wines.

Development of flavour defects in pasteurized double cream during storage at 6°C and at 10°C

A total viable count in excess of 1× 107 cfu/ml is required before organoleptic defects can be detected in pasteurized double cream, although defects were shown to be the results of non‐bacterial sources in creams from one creamery in the survey. Proteolysis was associated mainly with the presence of Bacillus spp. and resulted in the detection of a bitter flavour in the creams.

Enzymatic Control of Metability in a Direct Acidified Cheese Product

ABSTRACTAn enzymatic method based on a fungal protease derived from A. oryzae was developed to control the meltability of a direct acidified cheese product. The kinetics of activation and inactivation were delineated. Meltability values, as determined by the standard L.D. Schrieber test, were strongly correlated with proteolysis as measured in terms of nonprotein nitrogen (NPN). Excessive proteolysis resulted in textural and organoleptic defects (short and grainy texture, bitterness). Optimum conditions for enzymatic action were delineated in terms of desirable rheological characteristics and overall product quality.

Effect of Brandy upon the Quality and Changes in Composition of California-Type Sherry during Baking

1. The composition and quality of fortifying brandy has a corresponding influence upon the quality of Californiatype sherry not only after baking but after two years of wood aging. The characteristic which is most clearly attributable to the brandy used is a residual hotness in taste. 2. Sherry material which had high aldehyde contents lost part of the aldehydes during baking, owing to condensation or evaporation or probably both, under the conditions of the experiments described. The initial presence of aldehydes does not appear to be a requirement for obtaining the characteristic aroma and taste of baked sherry. 3. Sherry produced with brandy containing heads possesses organoleptic defects, especially hotness which is noticeable after 120 days of heating at 120° F., and it did not appear to possess any favorable flavor adjuncts that are not also present in sherry produced with clean brandy.