Search

We assessed the efficacy of Lactobacillus nodensis CSK964 as an adjunct culture in Gouda cheese under various industrial conditions. We set up 4 different systems: a direct vat inoculum with and without adjunct using the calf rennet Kalase, and an undefined bulk starter culture with and without adjunct using the microbial rennet Milase (both rennets from CSK Food Enrichment, Ede, the Netherlands). During ripening, we subjected the cheeses to the following analyses: viability of starter and adjunct cells, composition, proteolysis, and flavor development by detection of sulfur compounds and descriptive sensory analysis. In general, the presence of Lb. nodensis increased secondary proteolysis and influenced cheese flavor, particularly in relation to volatile sulfur compounds; hydrogen sulfide and methanethiol were present in higher abundances in cheeses containing Lb. nodensis. The primary starter also influenced the range of volatile sulfur compounds produced. Methanethiol and dimethyl disulfide were more abundant in the nisin-producing direct vat inoculum cheese with adjunct; hydrogen sulfide was more prevalent when bulk starter culture was used with Lb. nodensis. Sensory analysis revealed that the direct vat inoculum cheese with adjunct scored significantly better in terms of smell and taste than the direct vat inoculum cheese without adjunct and lacked the dominant sulfur flavors of the bulk starter cheese with adjunct. Subsequent analysis using lead acetate paper and modified motility broth as indicators of hydrogen sulfide production confirmed that Lb. nodensis produced hydrogen sulfide in broth and in the cheese matrix. This study suggests that the inclusion of Lb. nodensis as an adjunct culture can significantly alter the flavor profile of the final cheese. However, the selection of a suitable primary starter is imperative to ensure a desirable product.

Cheddar cheese was made using control culture (Lactococcus lactis subsp. lactis), or with control culture plus a galactose-metabolising (Gal+) or galactose-non-metabolising (Gal−) Streptococcus thermophilus adjunct; for each culture type, the pH at whey drainage was either low (pH 6.15) or high (pH 6.45). S. thermophilus affected the levels of residual lactose and galactose, and the volatile compound profile and sensory properties of the mature cheese (270 d) to an extent dependent on the drain pH and phenotype (Gal+ or Gal−). For all culture systems, reducing drain pH resulted in lower levels of moisture and lactic acid, a higher concentration of free amino acids, and higher firmness. The results indicate that S. thermophilus may be used to diversify the sensory properties of Cheddar cheese, for example from a fruity buttery odour and creamy flavour to a more acid taste, rancid odour, and a sweaty cheese flavour at high drain pH.

In cheese, a negative oxidation-reduction (redox) potential is required for the stability of aroma, especially that associated with volatile sulphur compounds. To control the redox potential during ripening, redox agents were added to the salted curd of Cheddar cheese before pressing. The control cheese contained only salt, while different oxidising or reducing agents were added with the NaCl to the experimental cheeses. KIO3 (at 0·05, 0·1 and 1%, w/w) was used as the oxidising agent while cysteine (at 2%, w/w) and Na2S2O4 (at 0·05 and 0·1%, w/w) were used as reducing agents. During ripening the redox potential of the cheeses made with the reducing agents did not differ significantly from the control cheese (Eh ≈ −120 mV) while the cheeses made with 0·1 and 0·05% KIO3 had a significantly higher and positive redox potential in the first month of ripening. Cheese made with 1% KIO3 had positive values of redox potential throughout ripening but no starter lactic acid bacteria survived in this cheese; however, numbers of starter organisms in all other cheeses were similar. Principal component analysis (PCA) of the volatile compounds clearly separated the cheeses made with the reducing agents from cheeses made with the oxidising agents at 2 month of ripening. Cheeses with reducing agents were characterized by the presence of sulphur compounds whereas cheeses made with KIO3 were characterized mainly by aldehydes. At 6 month of ripening, separation by PCA was less evident. These findings support the hypothesis that redox potential could be controlled during ripening and that this parameter has an influence on the development of cheese flavour.

Curd was washed to varying degrees during Cheddar cheese manufacture, by partial replacement of whey with water at the early stages of cooking, to give target levels of lactose plus lactic acid in cheese moisture of 5.3 (control), 4.5, 4.3 and 3.9% (w/w). The cheeses were matured at 8 °C for 270 days. While curd washing had little effect on composition or the mean levels of proteolysis (as measured by pH 4.6 soluble nitrogen and levels of free amino acids), it led to cheeses that were, overall, firmer and less brittle. Curd washing resulted in cheeses having lower levels of some volatile compounds, and being less acid, more buttery, sweeter, saltier and creamier than non-washed cheeses that had more 'sweaty', pungent and farmyard-like sensory notes. The results suggest that curd washing during Cheddar manufacture may be used as a means of creating variants with distinctive flavour profiles.

Oxidative analysis of omega-3-enriched fat spreads (oil-in-water-in-oil, O/W/O emulsions) was carried out using conventional lipid oxidation methods (lipid hydroperoxide and p-Anisidine values) and compared with volatile compound analysis using SPME-GC/MS and sensory evaluation. Fat spreads were produced using novel double-emulsion technology. More volatile compounds were detected in tuna oil-enriched spreads (Ross and Smith in Compr Rev Food Sci Food Saf 5:18–25, 2006) than control (no tuna oil) (Lund and Holmer in Eur Food Res Technol 212:636–642, 2001). As storage time of spreads increased, volatile concentration increased. Conventional lipid oxidation results correlated well with the GC/MS results, as the tuna spread had consistently higher values than the control spread. Lipid hydroperoxides and GC/MS volatile compounds increased with storage time, whereas p-Anisidine values remained level. The control spread achieved the highest score from the sensory panel for odour and flavour acceptability. Flavour of all tuna spreads became unacceptable after 8 weeks. To the authors’ knowledge, this is the first study-detecting volatiles using SPME-GC/MS, in omega-3-enriched double-emulsion fat spreads.

The incorporation of brewer's spent grain (BSG) into baked snacks (crispy-slices) was investigated in terms of nutritional, sensory and aromatic properties. Wheat flour was replaced with BSG at the levels of 10, 15 and 25%. Snacks containing 10% BSG exhibited high Crispiness index (Ci), low Crispiness work (Wc) and a high number of peaks during texture analysis, indicating that the crispiness of the samples was not negatively affected. However higher levels of BSG affected the texture and the crumb structure of snacks and the results were significantly different to the 100% wheat control. Addition of BSG altered the odour profile of the snacks as shown by the volatile profiles, however sensory results indicated that BSG-containing snacks at a level of 10% were highly acceptable and highlighted the possibility of using BSG as a baking ingredient in the formulation of enhanced fibre baked snacks.

The effect of varying salt (sodium chloride) addition levels of 0.50%, 1.25%, 1.80%, 2.25%, 2.50% and 3.00% (w/w) on the quality of Cheddar cheese was assessed. Reducing the salt adversely impacted Cheddar flavour and texture. The key compositional parameters of moisture-in-non-fat-substances and salt-in-moisture were most affected. Decreasing salt resulted in a concomitant reduction of pH, a slight reduction in buffering capacity and an increase in water activity and growth of starter and non-starter lactic acid bacteria that resulted in enhanced proteolysis. Lipolysis was not impacted by salt reduction. To produce quality reduced salt Cheddar cheese cognisance must be taken on how to reduce proteolysis, limit growth of NSLAB, reduce water activity, achieve pH 5.0–5.4 by modifications to the cheese making procedure to create a more appropriate environment for selected starter and/or adjunct cultures to generate acceptable Cheddar flavour and texture.

This study was undertaken to independently evaluate three commercial enzyme preparations: Accelase AM317, Accelase AHC50, Accelerzyme CPG used to accelerate Cheddar cheese ripening. Cheese trials were carried out in triplicate under identical conditions and compared with a control without an added enzyme preparation. All enzyme preparations were incorporated according to manufacturers' guidelines. The flavour of the Cheddar cheese was accelerated by the inclusion of each enzyme preparation, evident by more complex volatile profiles and the development of sensory attributes associated with aged Cheddar. Compositional parameters were not adversely impacted. Instrumental and descriptive textural analyses indicated some adverse rheological effects in cheeses produced by both Accelase blends, attributed to excessive primary proteolysis, and higher levels of moisture. The study has highlighted the potential of commercial accelerating ripening systems, but also identified that compositional and proteolytic indices need to be optimised to maximise their potential.

When monoglyceride (MG) was dispersed in oil above melting point, it formed self-assembled structures (liquid crystals) on cooling, which have the potential to structure oil in emulsion systems. In this study, the effects of MG on emulsion properties and subsequent flavor release were investigated. Model oil-in-water (O/W) emulsions stabilized with tween 20 (1% w/w, TW) and whey protein isolate (1% w/w, WPI) were prepared using microfluidization. All emulsions, with droplet size ranging from 170 nm to 387 nm, showed good stability during storage. In TW emulsions, DSC results indicated that development of MG crystalline structure occurred within 3 days of storage. The MG self-assembled structures largely modified the rheological behaviors of the emulsions, which showed an increased storage modulus on storage and the TW emulsion gave gel property (G′ > G″). The crystallinity was highly dependent on the content of MG in the system, while independent on the content of oil. However, the gel property was affected by the content of oil and MG. For WPI emulsions, very little MG crystallized during storage, and the WPI emulsions remained Newtonian. When limonene was introduced into the oil phase of these emulsions, a delay in the release of limonene in MG structured emulsions was observed by headspace analysis. Changes in emulsifier types and oil contents greatly influenced limonene release. The results of this study demonstrated the potential of using MG structured emulsion for controlled release of flavors, possibly in fat-reduced system.

Cheddar cheese was manufactured in triplicate from mid-lactation milk and analysed over a 270-day ripening period. The curd was washed in the cheese vat to give target levels of lactose plus lactic acid in cheese moisture (LLAMc) in the final cheese of 5.3 (control), 4.5, 4.3 and 3.9% (w/w); these values correspond to the expected LLAMc levels in non-washed cheeses made from milk with lactose levels of 4.8 (control), 4.6, 4.3 and 3.8% (w/w), respectively. Increasing curd washing from 0 to 33% of milk volume significantly reduced mean levels of total lactate and LLAMc over the ripening period. Conversely, it increased the mean cheese pH by ∼0.3–0.4 at times ≥ 90 days. The LLAMc was ∼1.0–1.6 units lower than predicted based on levels of milk lactose and curd washing. Otherwise, alteration of curd washing generally did not affect gross composition or microbiology of the cheese.

In this study, the growth of chloramphenicol-resistant bacteriocin-sensitive indicator strain Lactobacillus casei DPC 2048CM was evaluated in Cheddar cheese made with bacteriocin-producing Lactobacillus paracasei DPC 4715. No suppression of growth of the indicator strain was observed in the cheese during ripening, and no bacteriocin production by L. paracasei DPC 4715 was detected by the well diffusion method in cheese and cheese extracts. The bacteriocin produced by L. paracasei DPC 4715 was sensitive to chymosin and cathepsin D, and it may have been hydrolysed by the rennet used for cheese manufacture or by indigenous milk proteases.

The exopolysaccharide (EPS) produced by Lactococcus lactis subsp. cremoris DPC6532 has been shown to improve yield and functionality of reduced fat cheese. The aim of this work was to characterise the EPS produced by this strain to elucidate its role in fermented milk. The EPS was isolated from fermented skim milk, purified, quantified and imaged using atomic force microscopy and scanning electron microscopy. The monosaccharide composition and molecular weight of the EPS was also determined. The direct effect of the EPS on gelation and viscosity was investigated by oscillation rheometry on skim milk fermented with DPC6532 and its non-EPS-producing isogenic variant. The results indicated that this EPS gave a yield of 322 mg.L−1 in skim milk, had a molecular weight of ~2.8 × 105 g.mol−1 and was mainly composed of glucose and galactose (1.29:1). When observed by atomic force microscopy and scanning electron microscopy, a large size distribution was observed, with large aggregates consisting of several EPS molecules. Milk fermented with the EPS-producing culture was significantly more viscous than milk fermented with its non-EPS-producing isogenic variant. Gel strength was also significantly higher after 16 h of fermentation when the EPS-producing strain was used. This effect is thought to be due to depletion interactions caused by the EPS, which would stay dissolved in the serum phase, hence affecting gel viscosity and causing phase separation. The information provided by this study provided some insight to the information available on this specific EPS which can help to better understand its role in dairy matrices.

The objective of this study was to assess the effect of an exopolysaccharide-producing starter culture on milk coagulation and curd syneresis during the manufacture of half-fat Cheddar cheese by comparing the effect of an exopolysaccharide-producing starter with its non exopolysaccharide-producing isogenic variant. Coagulation and syneresis were monitored using light backscatter sensor technologies and the charge of the exopolysaccharide was also established. The distribution of the exopolysaccharide within the cheese microstructure was investigated by staining with Concavalin A and using confocal laser scanning microscopy. The study indicated that the exopolysaccharide produced by this starter culture did not interfere with coagulation but had a significant effect on reducing syneresis shortly after cutting. No charge was found on the exopolysaccharide under the measurement conditions. The exopolysaccharide was observed to be uniformly distributed throughout the cheese matrix and specifically located near the aqueous pores, possibly binding moisture and causing the observed decrease in syneresis.

Fat-reduced cheeses often suffer from undesirable texture, flavor, and cooking properties. Exopolysaccharides (EPS) produced by starter strains have been proposed as a mechanism to increase yield and to improve the texture and cooking properties of reduced-fat cheeses. The objective of this work was to assess the influence of an exopolysaccharide on the yield, texture, cooking properties, and quality of half-fat Cheddar cheese. Two pilot-scale half-fat Cheddar cheeses were manufactured using single starters of an isogenic strain of Lactococcus lactis ssp. cremoris (DPC6532 and DPC6533) that differed in their ability to produce exopolysaccharide. Consequently, any differences detected between the cheeses were attributed to the presence of the exopolysaccharide. The results indicated that cheeses made with the exopolysaccharide-producing starter had an 8.17% increase in actual cheese yield (per 100 kg of milk), a 9.49% increase in moisture content, increase in water activity and water desorption rate at relative humiditiesor=90%, significant differences in the cheeses microstructure, and a significant improvement in both textural and cooking properties, without negatively affecting the flavor profiles of the cheeses.

International audience; The ripening of industrial soft cheeses manufactured using a liquid pre-cheese produced from the ultrafiltration (UF) of milk was observed to be slow in comparison to that of cheese manufactured by a traditional process. Moreover, in the UF-cheeses investigated in this study, which were produced using Penicillium camemberti as the surface flora, several surface defects were observed: the texture was 'carton' like and the rind frequently detached from the cheese. To gain a fuller understanding of the development of these surface defects in UF-cheeses, the migration of different minerals and ions, and the study of the rind microstructure by scanning electron microscopy and X-ray mapping were performed. The results suggest that the slower diffusion of lactate, possibly due to the mineral layer at the surface of cheeses, acting as a barrier to its diffusion, may have caused an alteration in the metabolism and growth of the surface mould and may explain the surface defects of these UF-cheeses.; Les fromages à pâte molle industriels produits par ultrafiltration (UF) à partir d'un pré-fromage liquide présentent un affinage retardé par rapport à des fromages produits à l'aide d'un procédé traditionnel. De plus, des fromages UF modèles produits avec seulement Penicillium camemberti comme flore de surface montrent une texture de carton et la croûte se détache souvent du fromage. La caractérisation des migrations des minéraux et des ions et l'étude de la microstructure de la croûte de ces fromages modèles par microscopie électronique à balayage et micro-analyse X ont été réalisées afin de comprendre l'origine de ces défauts. La diffusion retardée du lactate, peut-être due à la présence d'une couche minérale à la surface des fromages, pourrait être à l'origine de changements de métabolisme et de la croissance de la moisissure et pourrait expliquer la moindre qualité des fromages.

The use of viable or attenuated Lactobacillus helveticus DPC 4571 for use in enzyme-modified cheese production was assessed. Optimal heat shocking conditions for attenuation of DPC 4571 were found to be 69°C for 25 sec. Enzyme-modified cheese was produced from an emulsion of pre-hydrolysed rennet curd, water, and butter fat. This substrate was heat-treated and inoculated with either an equivalent level of viable or attenuated cells of DPC 4571 and further incubated under controlled conditions. The heat-treated products produced using attenuated DPC 4571 had a preferred sensory character with strong cheesy savory notes, enhanced secondary proteolysis, and more key volatile flavor compounds than those produced with viable DPC 4571. However, prolonged incubation (>16 h) resulted in growth of advantageous enterococci, which adversely influenced the sensory profile.

The rapid release of intracellular enzymes due to autolysis of lactic acid bacteria in the cheese matrix has been shown to accelerate cheese ripening. The objective of this work was to investigate the evolution of the flavour precursors, individual free amino acids (FAAs), free fatty acids (FFAs) and volatile compounds that contribute to the sensory profiles of cheeses at 2, 6 and 8 months of ripening in Cheddar cheese manufactured using starter systems which varied with respect to their autolytic properties. Starter system A contained a blend of two commercial Lactococcus lactis strains (223 and 227) which had a low level of autolysis. System B was identical to A but also included a highly autolytic strain of Lactobacillus helveticus (DPC4571). System C contained only strain DPC4571. Levels of all individual FAAs were elevated in cheeses B and C relative to A after 2 months of ripening. By 8 months of ripening the main FAA were glutamate, leucine, lysine, serine, proline and valine. Levels of C6:0, C8:0, C12:0 and C18:0 fatty acids did not vary greatly over ripening, while levels of C4:0, C10:0, C14:0, C16:0 and C18:1 were elevated in cheeses B and C. Principal component analysis of the headspace volatiles separated cheese A from cheeses B and C. Cheeses B and C had highest levels of dimethyl disulphide, carbon sulphide, heptanal, dimethyl sulphide, ethyl butanoate, 2-butanone, and 2-methyl butanal and were described as having a ‘caramel’ odour and ‘sweet’, ‘acidic’ and ‘musty’ flavour. Cheese A had highest levels of 2-butanol, 2-pentanone, 2-heptanone, 1-hexanol and heptanal and was described as having a ‘sweaty/ sour’ odour and ‘soapy’, ‘bitter’ and ‘mouldy’ flavour. The results highlight the impact of starter lactococci on flavour precursor development and the positive effect of Lb. helveticus and the lysis of this strain on enhancing levels of substrate and flavour precursors early during ripening resulting in early flavour development.

Fast-ripened Cheddar cheeses for ingredient purposes were produced by addition of a dried enzyme-modified cheese (EMC; 0.25 and 1 g/100 g of milled curd) at the salting stage during a standard Cheddar cheese-making procedure. Populations of starter and nonstarter lactic acid bacteria (NSLAB), levels of proteolysis and lipolysis, volatile analysis, and flavor development (by quantitative descriptive sensory analysis) were monitored over a 6-mo ripening period. Levels of free AA and free fatty acids were elevated in the experimental cheeses on d 1 because of inclusion of the EMC. Counts of NSLAB were also elevated in the experimental cheeses compared with the control cheese from the start of ripening. Levels of free AA were slightly elevated in the experimental cheeses at 1, 2, and 4 mo, but significantly greater accumulations were detected by 6 mo of ripening, with His, Leu, and glutamate reflecting the greatest increases. Levels of long-chain free fatty acids increased up to 2 mo, indicating an initial stimulation of lipolysis, but had decreased by 6 mo, indicating greater catabolism, probably caused by NSLAB and increased starter lysis. Principal component analysis of the volatile compounds showed few differences in the aroma profiles among the cheeses up to 4 mo of ripening, but a large separation of the cheeses supplemented with EMC relative to the control was observed by 6 mo. Sensory analysis of the cheeses with added EMC showed an acceleration of 2 mo in flavor development compared with the control cheese with the addition of 1 g/100 g of EMC developing a flavor profile at 4 mo similar to the control cheese at 6 mo of ripening. However, atypical Cheddar flavors developed on prolonged storage. This study shows the potential of adding EMC during Cheddar production to produce a fast-ripened ingredient-type Cheddar cheese.

The impact of elevated ripening temperatures of varying duration to accelerate ripening and flavour development in Cheddar cheese was investigated using multi-variate statistical analysis of biochemical and descriptive sensory data. Descriptive sensory analysis was carried out by 13 trained assessors, using a vocabulary of 21 terms, to quantitatively describe cheese odour and flavour. Twelve attributes significantly discriminated (P

Young Tilsit cheese is traditionally smeared during ripening using smear liquid from older cheese which facilitates the development of surface flora, but this practice is undesirable from the point of view of hygiene. The objectives of this study were to investigate an alternative to this traditional practice involving a defined-strain surface starter. Two trials of Tilsit cheese were undertaken. In Trial 1, cheese were smeared with a reference smear (R1; old–young smearing) or defined-strain smears, i.e., Mix A (Brevibacterium linens 5 Br5, Microbacterium gubbeenense CA12, Br. casei 047-0399, Corynebacterium casei CA3, Staphylococcus equorum STAPH 2 and Debaryomyces hansenii 6004) or Mix B (as Mix A but C. variabile 025-0165 was used instead of C. casei CA3). In Trial 2, the cheese were smeared with a reference smear (R2) or defined-strain smears, i.e. Mix C (strains as in Mix A except S. equorum STAPH 2 and D. hansenii 6004 were added to the brine) or Mix D (strains as in Mix C plus S. sciuri STAPH 4 and C. variabile 025-0165). Compositional analysis indicated that the surface of the cheese differed from the core due to the action of the smear but that the compositions of the cheese made with the defined strain smear were similar to those made with the reference smears. Levels of pH 4.6-soluble nitrogen, expressed as a percentage of total nitrogen, increased more rapidly at the surface than in the core, reflecting the high level of proteolysis at the higher pH values, but levels were similar in all cheese. Principal component analysis of reverse-phase HPLC chromatograms and data from individual free amino acid analysis separated the surface and core samples of all cheese. Cheese made with the reference smears (R1, R2) were separated from those made with defined strain smear by the end of ripening, reflecting the different proteolytic systems associated with the organisms in the different smears used.

The rapid release of intracellular enzymes due to autolysis of lactic acid bacteria in the cheese matrix post-manufacture is thought to play a role in the acceleration of cheese ripening. To investigate this hypothesis Cheddar cheese was manufactured using three related starter systems which varied with respect to their autolytic properties. Starter system A contained a blend of two Lactococcus lactis strains (223 and 227) which had a low level of autolysis. System B was identical to A but included an adjunct of a highly autolytic strain of Lactobacillus helveticus (DPC4571). System C consisted only of strain DPC4571 as starter. The cheeses were evaluated during ripening for key ripening indices including autolysis of starter cells by release of intracellular marker enzyme lactate dehydrogenase (LDH), composition, proteolysis and flavour development by descriptive sensory analysis. Populations of Lb. helveticus DPC4571 decreased rapidly in cheeses B and C and were not detected by 8 weeks. The level of starter culture autolysis proceeded in the order C≫B>A. Levels of proteolysis were elevated in cheeses B and C relative to A. Principal component analysis of the sensory data separated the character of cheese A from that of cheeses B and C. Cheeses B and C developed a unique ‘balanced’ ‘strong’ flavour early in ripening with a ‘caramel’ and ‘musty’ odour and ‘sweet’ ‘astringent’ flavour compared to cheese A. Hierarchical cluster analysis grouped C at 2 months with B at 6 and 8 months reflecting accelerated flavour development. Proteolytic and sensory data support the hypothesis that autolysis accelerates the rate of cheese ripening.

peer-reviewed A total of twelve strains of lactococci were isolated from grass and vegetables (baby corn and fresh green peas). Ten of the isolates were classified as Lactococcus lactis subsp. lactis and two as Lactococcus lactis subsp. cremoris based on 16S rDNA sequencing. Most of the plant-derived strains were capable of metabolising a wide range of carbohydrates in that they fermented D-mannitol, amygdalin, potassium gluconate, l-arabinose, d-xylose, sucrose and gentibiose. None of the dairy control strains (i.e. L. lactis subsp. cremoris HP, L. lactis subsp. lactis IL1403 and Lactococcus lactis 303) were able to utilize any of these carbohydrates. The technological potential of the isolates as flavour-producing lactococci was evaluated by analysing their growth in milk and their ability to produce volatile compounds using solid phase micro-extraction of the headspace coupled to gas chromatography–mass spectrometry (SPME GC–MS). Principal component analysis (PCA) of the volatile compounds clearly separated the dairy strains from the plant derived strains, with higher levels of most flavour rich compounds. The flavour compounds produced by the plant isolates among others included; fatty acids such as 2- and 3-methylbutanoic acids, and hexanoic acid, several esters (e.g. butyl acetate and ethyl butanoate) and ketones (e.g. acetoin, diacetyl and 2-heptanone), all of which have been associated with desirable and more mature flavours in cheese. As such the production of a larger number of volatile compounds is a distinguishing feature of plant-derived lactococci and might be a desirable trait for the production of dairy products with enhanced flavour and/or aroma.

The aim of this study aimed to investigate food pairings as an important sensory phenomenon in order to determine how different components in the selected food pairings affect and interact with other components. Three novel food pairings (banana and bacon, banana and olive oil, and banana and rice) were selected. A conjoint approach utilising qualitative (organic volatile analysis and descriptive sensory analysis) and quantitative (comparable semi quantitative organic volatile analysis and affective sensory tests) methods of analysis n an attempt to elucidate the success or failure of selected food pairings. Free choice profiling (descriptive sensory analysis) data was analysed using Generalised Procrustes analysis. The correlation between volatile analysis and descriptive sensory analysis results were analysed using ANOVA partial least squared regression. Hedonic results were analysed using a Friedman rank sum test, while preference results were analysed using a Wilcoxon signed rank test. The food pairings of banana and bacon and banana and rice were found to be liked significantly more than banana and olive oil. The results of this study suggest that synergistic and/or antagonistic interactions between the volatile compounds in the foods influenced the hedonic ratings of these food pairings.

The appearance of undesirable bitter taste in Ragusano cheese was investigated by comparing the composition of 9 bitter cheeses with that of 9 reference cheeses of good quality by means of chemical, electrophoretic, and chromatographic analyses. Rates of proteolysis were significantly affected in cheeses of different quality. Primary proteolysis, as measured by pH 4.6-soluble N, was significantly greater in bitter cheeses compared with reference samples. Urea-PAGE profiles showed an almost complete breakdown of caseins in bitter cheeses and the further degradation of primary peptides into smaller compounds not detectable by this technique. Cheeses with defects had significantly lower levels of secondary proteolysis as reflected by the percentage of pH 4.6-soluble N soluble in 12% trichloroacetic acid and the amounts of total free amino acids. Peptides separated by reversed phase-HPLC revealed that the large and significant differences in peptide profiles of the soluble fractions between bitter and reference cheeses were mainly due to a much higher proportion of hydrophobic peptides in the former. The occurrence of bitterness in Ragusano cheese was therefore attributable to unbalanced levels of proteolysis and peptidolysis. Extensive degradation of caseins and primary peptides by activities of proteases produced large amounts of small- and medium-sized hydrophobic peptides that were not adequately removed by peptidases of microflora and therefore accumulated in cheese potentially contributing to its bitter taste. The presence of these compounds in bitter cheeses was related to high salt-in-moisture and low moisture contents that limited the enzymatic activities of microflora important in secondary proteolysis. Combining salt-in-moisture and the ratio of hydrophobic-to-hydrophilic soluble peptides resulted in the best logistic partial least squares regression model predicting cheese quality. Although bitterness is known to be rarely encountered in cheese at salt-in-moisture levels >5.0, all of the bitter cheeses analyzed in this study had salt-in-moisture levels much greater than this value. According to the logistic model, a risk of bitterness development may exist for cheeses with a midrange (5 to 10%) salt-in-moisture content but with an inadequate level of secondary proteolysis.

The effects of defined lactococcal starter strains (UC317, NCDO763, HP or SK11) on proteolysis in Turkish White-brined cheese were studied throughout ripening (1, 15, 30, 60 or 90 days). No significant differences were found in the gross compositions of the cheeses made with different strains, although the pH values were slightly different. Proteolysis was assessed at each ripening time by urea-polyacrylamide gel electrophoresis (urea-PAGE) of the pH 4.6-insoluble fractions and by reversed-phase high performance liquid chromatography (RP-HPLC) of the pH 4.6-soluble, the 70% (v/v) ethanol-soluble or 70% (v/v) ethanol-insoluble fractions of the cheese samples. Only minor differences were apparent during early ripening (at 1 or 15 days) but considerable differences were found in the urea-PAGE patterns after 60 days of ripening. Urea-PAGE of the pH 4.6-insoluble fraction of the cheeses showed that ?s1-casein was hydrolysed more rapidly than ß-casein. The use of single strains of Lactococcus markedly influenced the peptide profiles obtained by RP-HPLC of the pH 4.6-soluble or 70% (v/v) ethanol-soluble or 70% (v/v) ethanol-insoluble fractions of the cheeses. Significant differences in the level of free amino acids were also observed between the cheeses; the cheeses made with NCDO763 or SK11 had the highest concentrations of free amino acids. The use of different lactococcal strains in the manufacture of Turkish White-brined cheese affected the degradation of ?s1-casein, the formation of peptides detectable by RP-HPLC and the level of free amino acids. © 2004 Elsevier Ltd. All rights reserved.