The denaturation and gelling properties of mixed systems of β-lactoglobulin and sodium-alginate have been investigated as a function of alginate molecular weight, chemical composition, concentration, pH and ionic strength. Differential scanning calorimetry and small strain oscillatory measurements showed that denaturation temperature were lower than the gelling temperatures under the conditions examined. The denaturation temperatures were dependent on both pH and ionic strength, but unaffected by alginate concentration and type. The mechanical and textural properties of mixed gels of β-lactoglobulin and sodium alginate were dependent on several factors; the gel strength increased as a function of alginate concentration under ambient conditions, and decreased as the pH and/or the ionic strength were changed. High molecular weight alginate gave the most pronounced effects, probably due to the accessibility of the alginate for protein binding. The chemical composition of the alginate had negligible effect on the mechanical properties of the gels. PRACTICAL APPLICATIONS: As both proteins and polysaccharides are widely used in the food industry, it is important to understand the interactions between these two biopolymers in order to envisage final product properties. The present article gives an overview of several important parameters when mixing β-lactoglobulin and sodium alginate. β-Lactoglobulin is the main protein in whey and one of the major food protein ingredients. Alginate is a polysaccharide that is often used in the food industry because of its functional properties. This study shows that if the conditions and the alginate type are adequately chosen, the textural properties of food products can be controlled and tailored.

Starter cultures of lactic acid bacteria (Lactobacillus fermentum MINF99, Weissella confusa MINF8, Lactobacillus plantarum MINF277, Lactobacillus brevis MINF226, and Lactobacillus paracasei subsp paracasei MINF98) were used to ferment Bushera during fermentation (96 h). Organic acids and volatile compounds produced during starter and natural fermentation were investigated. Microbial counts, pH, and sugars were also determined. LAB counts increased from 5.87 +/- 0.00 to 8.32 +/- 0.02 log cfu mL(-1) while yeasts increased from 4.39 +/- 0.02 to 7.10 +/- 0.04 log cfu mL(-1) during natural fermentation. The pH decreased from 6.5 to 3.55-4.0. W. confusa MINF8 attained similar final pH (3.55) as naturally fermented Bushera. Lactate was the dominant acid and varied between 0.34% and 0.66%. W. confusa MINF8 produced the highest amounts of lactate (0.66%). Lactate content in naturally fermented Bushera was 0.89%, 96 h. Glucose and maltose decreased from 8.64-9.27 g kg(-1) to 0.13-2.11 g kg(-1) and 7.95-8.42 g kg(-1) to 0.06-2.66 g kg(-1), respectively, in all starter fermented Bushera within 24 h. Glucose and maltose increased during the first 24 h of natural fermentation and then decreased. No citrate was detectable after 24 h. Succinate, pyruvate, and pyro-glutamate were detected and varied between 1.44 and 1495.93 mg kg(-1). Methyl alcohols increased with fermentation time and ranged between 0.02 and 0.53 mg kg(-1). Methyl alcohols concentration of naturally fermented Bushera were significantly higher (P < 0.05) than those of starters after 24 h. Acetaldehyde levels detected in starter fermented bushera was below 5 mg kg(-1) compared to 17.6 mg kg(-1) of naturally fermented Bushera. All starters except L. paracasei subsp. paracasei MINF98 reduced the methyl aldehydes within 12 h to levels ranging between 0.01 and 0.06 mg kg(-1). Ethyl alcohol was the predominant volatile compound and ranged from 2.16 to 1406 mg kg(-1). W. confusa MINF8 produced the highest amounts of ethyl alcohol (1406 g kg(-1)). Maximum ethyl alcohol amount detected in naturally fermented Bushera was 10.4 g kg(-1). Other volatiles detected were butanone, 2, 3-pentanone, diacetyl and ethyl acetate. The study has shown that all starters have ability to singly ferment Bushera. The varying amounts of the volatile compounds observed may influence the sensory properties of Bushera and may be the basis for selecting suitable starters for commercial production.

Four types of Obushera, a fermented millet or sorghum beverage: Ekitiribita, Obuteire, Obutoko and Enturire were analyzed for their physico-chemical properties, sugars, organic acids and volatile compounds during fermentation. Standard chemical methods were used to determine the physico-chemical properties of Obushera. The organic acids, carbohydrates, glucose, fructose and maltose were analyzed by highperformance liquid chromatography. The pH of all Obushera varied between 4.00±0.10 and 4.42±0.11 after 4 days of fermentation. The pH of Obuteire, Obutoko and Enturire dropped below 4.5 within one day of fermentation. Acidity ranged between 0.13% (Ekitiribita) to 1.33% (Enturire) after 4 days of fermentation. Dry matter decreased and varied between 5.4 and 22% after 4 days of fermentation. Fermentation resulted into a 20–40% reduction of dry matter in Obutoko, Obuteire and Enturire. Enturire had the highest dry matter content and decreased from 22% to 13%. Fermentation resulted in an apparent increase in protein concentration (5.7– 12.3%). Flavour compounds identified included sugars, organic acids, aldehydes, ketones, alcohols and esters. Enturire contained the highest (p < 0.05) concentrations of most flavor compounds. Sugars (maltose, glucose and fructose) were reduced during fermentation. The predominant organic acids detected were lactate, acetate and succinate and increased with fermentation time. Alcohols identified in Obushera were ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol and 2-methyl-1-butanol and increased during fermentation. Ethanol was the predominating alcohol reaching a maximum of 0.8–1.0% (Obuteire and Obutoko) and 4.5% in Enturire during fermentation. The aldehydes detected in Obushera were acetaldehyde, 2-methyl-1- propanal, 2-methyl-1-butanal and 3-methyl-1-butanal and varied from 0.1 mg kg-1 to 6.8 ± 1.2 mg kg-1. Diacetyl, acetoin and 2,3 pentanedione were the ketones identified in Obushera. Esters detected in Obushera included ethyl lactate, ethyl acetate, ethyl butyrate and isobutyl acetate. Significantly higher (p <0.05) amounts of esters were detected in Enturire than in the other types of Obushera. Principal Component analysis, grouped Obushera into three categories (Ekitiribita, Obuteire/Obutoko and Enturire) based on flavour profile differences.

A tomato flavor enhancer, 2-isobutylthiazole (IBT), was added (5 mg/kg) to dressings emulsified with either a whey protein concentrate-80 (WPC-80), a WPC-80 hydrolysate or β-lactoglobulin at high pressure (70 MPa) at either 20 or 75 °C. The short (2-4 min), high-temperature treatment left the proteins essentially unchanged. IBT addition gave a dominant, green tomato flavor that masked the intrinsic odor of the WPC-80 hydrolysate but enhanced bitter flavor. The sensory IBT odor intensity was determined by oil level (5-30%) and pH; pH 4.0 gave higher IBT odor than pH 6.5. The green (IBT) odor release correlated with the sensory viscosity (p = 0.001) and with instrumentally determined complex modulus (p = 0.001), but not to the dressings’ microstructure. The presence of small (<<1.5 µm) oil particles that were difficult to identify from images may explain why no correlation between green odor and microstructure was found. Headspace analysis significantly detected differences in the release of IBT from the different protein types: WPC-80 dressings released the most and β-lactoglobulin the least amounts of IBT into headspace. As this difference in release of IBT among proteins could not be verified by sensory analysis, it may bear no relevance for perception.

ABSTRACT The purpose of this study was to describe the sensory characteristics of traditionally produced Obushera and their influence on consumer acceptability using focus group discussions, a descriptive panel and a consumer acceptability panel. Four types of Obushera of commercial importance including: Obutoko and Enturire (sorghum based) plus Obuteire and Ekitiribita (millet‐based) were identified. Descriptive profiles of the four types showed that they are sensorially distinct products. Preliminary studies indicated that their acceptability was significantly (P < 0.05) affected by producer and duration of fermentation. Some of the factors that influence the sensory quality of Obushera include: cereal variety, quantity of ash used during malting, length of drying period of the sprouted grain and back slopping. Obushera is a range of sensorially distinct products varying in taste, aroma and texture. These products may appeal to different consumer tastes and market segments. Variation in sensory attributes is due to the different raw materials used, stage of fermentation and to the effect of different producers among others. Therefore, efforts toward improving the production process, quality and safety of Obushera should be more product‐specific.PRACTICAL APPLICATIONSObushera is one of the many popular traditional fermented products whose production has not yet been commercialized. This is partly due to its being a spontaneously fermented product often resulting in inconsistencies in quality. Therefore understanding the sensory characteristics of Obushera and how these relate to its acceptability is crucial in guiding the process of improving the processing of Obushera for commercial production. These results can be used to guide studies involved with selection of starter cultures and quality raw material. This study can also act as a guide to research related to similar products in Africa such as Togwa (Tanzania), Kirario (Kenya), Dolo and Pito (West Africa) among others. A more in depth consumer study involving large numbers of consumers would be necessary to confirm these findings.

This work comprises the study of the thermal treatment of beta-lg and its denaturation as a function of pH and ionic strength followed by differential scanning calorimetry. The concentration of protein was 14 (w/v)% in order to study the behaviour of highly concentrated beta-lg solutions during heating. The denaturation temperature of beta-lg was dependent on both pH and ionic strength, meaning that electrostatic interactions between protein monomers in the native state were important for the denaturation of beta-lg. The thermograms from the calorimetric measurements also revealed that the quarternary structure of beta-lg at pH-values close to the isoelectric point was influenced by the presence of salt and the nature of the salt (NaCl, KI and LiI). Small exotherms emerged in the thermograms at the low temperature side of the denaturation temperature for beta-lg. The presences of these exotherms are probably caused by restructuring of the quarternary structure of native beta-lg prior to denaturation, due to dissociation into smaller entities and possible also formation of a liquid crystalline-like structure in the highly concentrated protein solution. The present study provides a contribution to the understanding of the importance of the electrostatic interactions between native beta-lg molecules and how different salts and ionic strengths affect the denaturation properties of the protein in concentrated systems. (C) 2009 Elsevier Ltd. All rights reserved.

Protein degradation of caprine whey by human proteolytic enzymes was studied with regard to antibacterial effect on Listeria monocytogenes. The digestion was performed by a two-step degradation-assay, using human gastric juice (HGJ) at pH 2.5, and human duodenal juice (HDJ) at pH 8. Protein profiles were studied by SDS-PAGE after each step and compared with degradation performed by commercial enzymes. Both types of enzymes, both human and commercial, left most of beta-LG intact. However, proteins like serum albumin, laktoferrin and immunoglobulins were rapidly degraded. Only minor parts of alpha-lactalbumin (alpha-LA) was degraded by human enzymes, while treatment with commercial enzymes gave full degradation of(alpha-LA. The two types of enzymes resulted in different peptide profiles, where the commercial enzymes degraded whey into smaller peptides much more efficiently.The protein digests produced by HGJ and HDJ were screened for antibacterial effects against L. monocytogenes, a food born bacteria responsible for fatal and sometimes deadly infections. Cells of L. monocytogenes were strongly inhibited by caprine whey obtained after reaction with both HGJ and HDJ. Undigested caprine whey and the products from the first step of digestion with HGJ demonstrated no significant effect. This indicates that during digestion the antibacterial effect of caprine whey hydrolysates are most effective in the duodenum. This gives a promising opportunity to inhibit listeriosis in humans, and results are also useful for development of dietary supplement, nutraceuticals and functional foods. (C) 2008 Elsevier B.V. All rights reserved.

The aim of this study was to perform a screening of various milk protein samples of both cow and goat origin to study their in vitro immunomodulating properties on human peripheral blood mononuclear cells (PBMC).The Protein content in the milk of the two different species varies most notably in the amount of alpha(s1)-casein. A high degree of genetic polymorphism is related to the goat alpha(s1)-casein genes resulting in a variable amount of total protein in the goat milk.The milk proteins were hydrolysed using human gastric and duodenaljuice or commercial pig derived enzymes to simulate in vivo digestion. Although different immunomodulating effects caused by various milk protein components have been observed, the mechanisms underlying these effects are not always known. In addition, most studies on the immunomodulating properties of milk protein digests have used a wide variety of commercial enzymes to simulate in vivo digestion. Exploring the difference in immunomodulating properties of milk protein-derived peptides produced by the aid of enzymes from human gastric secretions, compared to those produced by commercial enzymes, is a novel approach that may be of great importance. It could help to explore which peptides are actually produced during in vivo early digestion of milk and how they influence the immune system.Especially the whey protein concentrates from goat and cow showed a dose-dependent inhibition of human PBMC proliferation in vitro. This effect could neither be explained by a toxic effect on the PBMCs as shown by a standard viability test, nor by induction of apoptosis caused by the same milk protein samples. We suggest that intact or hydrolysed components in the milk protein samples affect the production of activation signals thereby inhibiting lymphocyte proliferation. (C) 2008 Elsevier B.V. All rights reserved.

Aims: We describe a novel DNA-micro-array-based method that targets 16SrDNA to quantify changes in both the total bacterial DNA and the species-specific DNA composition. Methods and Results: Quantifications were achieved by combining competitive PCR for quantitying total bacterial DNA with quantification of specics-specific DNA composition based on signature 16S rDNA sequences. We constructed 11 different probes, which were evaluated on 21 different strains, in addition to complex samples. The signals obtained with sequence-specific labelling of the probes corresponded well with what should be expected based on 16S rDNA phylogenetic reconstruction. The quantification of species-specific DNA composition showed that the micro-array approach could be used to accurately determine differential growth of bacteria in mixed samples. We analysed samples containing mixtures of Lactococcus lactis and different species of propionibacteria during a 2-week incubation period. Lactococcus lactis grew fast, reaching a maximum after 12 h, Propionibacterium acidipropionici and Propionibacterium freudenreichii reached a maximum after 48 h, whereas Propionibacterium jensenii showed a slow increase during the whole growth period. The 16S rDNA total bacterial DNA quantification was compared with real-time PCR, absorbance measurements (ABS(600)) and colony forming units (CFU). Conclusion: The accuracy of the array approach was in the same range or better than the alternative techniques. The potential of the 16S rDNA micro-array method was further demonstrated using a liquid cheese model. Significance and Impact of the Study: This is to our knowledge the first time quantification of the total bacterial DNA and the species-specific DNA compositions of mixed populations have been achieved in the same assay.

The growth and sporulation of Bacillus cereus NVH 45 in a fermentor with controlled pH or simulated pH conditions were investigated. The study was carried out in a fermentor to measure the influence of a rapid and a slow lactic acid production on the inhibition of B. cereus in a controlled environment during the initial part of fermentation and to observe if other factors than lactic acid influenced the inhibition. In the controlled pH experiments the pH was allowed to decrease to an end pH 5.0, 5.5 or 6.0 either by Lactobacillus casei 2756 (a fast acid producer) or Lactobacillus acidophilus NCFB 1748 (a slow acid producer). In co-cultures of Lb. casei 2756 and B. cereus NVH 45, low numbers (10-70 cfu/ml) of B. cereus NVH 45 were observed at end pH 5.5 (72 h) while at pH 5.0 no viable cells (< 10 cfu/ml) were detected (48-72 h). B. cereus NVH 45 did not sporulate in co-culture with Lb. casei 2756. In co-culture with Lb. acidophilus NCFB 1748, B. cereus NVH 45 sporulated and survived as spores. In these co-cultures B. cereus NVH 45 grew to higher maximum counts (> 10(7) cfu/ml) than with Lb. casei 2756 (< 10(7) cfu/ml). Significantly different amounts of lactic acid were observed between the two co-cultures after 7 and 12 h. A rapid decrease of pH appears to prevent B. cereus from sporulating and it seems that it is enough to just reach pH 5.0 rapidly and keep that pH to achieve the desirable inhibition of B. cereus.In the simulated pH experiments B. cereus NVH 45 was inoculated in the fermentor and the different pH developments from different LAB strains were monitored by addition of lactic acid. These experiments showed the same tendency: a fast pH reduction during the initial hours of fermentation, simulating lactococci, resulted in complete inhibition of B. cereus NVH 45 (< 10 cfu/ml). However, when simulating the pH development of the two different Lactobacillus strains, complete inhibition of B. cereus NVH 45 was not seen. In co-cultures competition for nutrients with consequences for cell density appears to be important. Based on these results it seems that B. cereus must reach a certain density to induce sporulation. (c) 2005 Elsevier B.V. All rights reserved.

Dressings were produced according to a fractional factorial design with protein type, protein level, oil level, pH, addition of NaCl, CaCl2 and sucrose, and processing temperature as design variables. The dressings were produced by high-pressure, and were model-systems emulsified and stabilized with different whey protein types.The dressings were characterized by sensory analysis with regard to smell and taste, and texture properties. Analysis of variance revealed that oil level explained 56% of the variation in the sensory attribute viscosity. Protein type explained the largest part of the sensory attributes syneresis and smell. Addition of CaCl2 increased syneresis and gave a bitter tasteThe dressings' microstructures were captured by Scanning electron micrographs (SEM). The images were analysed using two different algorithms for feature extraction; the ABDF method, measuring absolute differences in greyness between pixels at fixed distances, and a local box-counting (fractal) method measuring the maximum differences in greyness within boxes of fixed sizes. After vectorization of the images by the algorithms, the vectors were analyzed to find which design variables influenced the vectors the most.The analysis of variance revealed that protein type was the design variable that could clarify the largest part of the variation that could be explained in the images, followed by addition of NaCl. The fat was not visible in the images, and was hardly recognized by the feature extraction algorithms.The correlation between viscosity and image analysis was fair, as the oil was not detected by the images or vectorized images. Sensory attributes explained by protein type or other design variables visible in the images were well explained by images.

This study aimed at investigating effects of α s1 -casein polymorphism on milk composition, mean size of casein micelles and rennet coagulation properties in individual milk samples form Norwegian Dairy Goats. A remarkable high frequency (70 %) of the α s1 -casein null variant was found among Norwegian Dairy Goats. The composition of strong milks was characterized by a significantly higher content of crude protein and casein, higher Ca-ion activity, lower milk pH, smaller casein micelles and higher gel strength (A30) than null milks.

ABSTRACT The purpose of this study was to investigate the frequency of production of the bacteriocin propionicin T1 and the protease-activated antimicrobial peptide (PAMP) and their corresponding genes in 64 isolates of classical propionibacteria. This study revealed that these genes are widespread in Propionibacterium jensenii and Propionibacterium thoenii but absent from the remaining species of classical propionibacteria that were studied. The pro-PAMP-encoding gene ( pamA ) was found in 63% of the P. jensenii strains and 61% of the P. thoenii strains, and all of these strains displayed PAMP activity. The propionicin T1-encoding gene ( pctA ) was present in 89% of the P. thoenii strains and 54% of the P. jensenii strains. All P. thoenii strains containing the pctA gene exhibited antimicrobial activity corresponding to propionicin T1 activity, whereas only 38% of the pctA -containing P. jensenii strains displayed this activity. Sequencing of the pctA genes revealed the existence of two allelic variants that differed in a single nucleotide in six strains of P. jensenii ; in these strains the glycine at position 55 of propionicin T1 was replaced by an aspartate residue (A variant). No strains harboring the A variant showed any antimicrobial activity against propionicin T1-sensitive bacteria. An open reading frame ( orf2 ) located immediately downstream from the pctA gene was absent in three strains containing the G variant of propionicin T1. Two of these strains showed low antimicrobial activity, while the third strain showed no antimicrobial activity at all. The protein encoded by orf2 showed strong homology to ABC transporters, and it has been proposed previously that this protein is involved in the producer immunity against propionicin T1. The limited antimicrobial activity exhibited by the strains lacking orf2 further suggests that this putative ABC transporter plays an important role in propionicin T1 activity.

Thirty-eight model dressings were produced according to a fractional factorial design. Dressings prepared with hydrolysed whey protein concentrate (DH 1 with Corolase PN-L from RohmGmbH) were compared to dressings produced with whey protein concentrate (WPC) and purified beta-lactoglobulin (beta-LG) as emulsifiers. The dressings were produced in a high-pressure homogeniser at similar to70 kPa pressure. The factors varied were protein%, oil%, pH, process temperature, and in addition NaCl, CaCl2 and sucrose.The dressings were evaluated with regard to textural and structural properties by emulsion stability (ES), rheological measurements, scanning electron microscopy (SEM) and image analysis.The dressings produced spanned from thin milk-like liquids to thick pastes. WPC formed mainly thin dressings, while dressings produced by hydrolysate and beta-LG were mainly creamy. None of the dressings showed separation of the oil phase, however some syneresis of water was observed. Variation in protein and oil content affected the stability of the dressings. When the protein content was increased from 2 to 4% and the oil content from 5 to 30%, the hydrolysate and beta-LG dressings became more stable, in contrast to WPC dressings, which became less stable. Addition of sucrose increased the stability and the phase angle of all protein types.High processing temperature (75 degreesC) affected the dressings differently. A positive effect was observed on the stability of WPC and beta-LG dressings, while hydrolysate dressings showed reduced stability, except for the combination of low pH (4.0), high protein (4%) and fat content (30%). This dressing was highly stable at high processing temperature. SEM-images revealed that the fat globule size was smallest for WPC (0.1-0.9 mum) and increased in the order WPC < hydrolysate < beta-LG. The microstructure of WPC dressing showed homogenous, non-aggregated structure in contrast to hydrolysate and beta-LG dressing, which showed highly ordered, aggregated structure which supports the rheological measurements for gel formation. Image analysis indicated that the microstructure of the dressings made with different protein types were special and identifiable. (C) 2003 Elsevier Ltd. All rights reserved.

During co-culture of Lactobacillus (five strains) or Lactococcus (two strains) with Bacillus cereus, organic acids and other potentially antimicrobial metabolites are produced. Lactic acid was produced at very different rates by the lactic acid bacteria (LAB) and the final concentrations varied much, however, the crucial point of rapid pH reduction during the initial hours of fermentation coincides with lactic acid production. Moderate amounts of acetic acid were produced during fermentation and the final concentrations were much smaller compared to lactic acid. According to these experiments, production of diacetyl, carbon dioxide and ethanol was considered too small to contribute to inhibition of B. cereus. The inhibitory substance produced by the LAB strains was not sensitive to proteinase K, trypsin or pepsin, so it was not likely that the LAB strains produced bacteriocins antagonistic against B. cereus. The strains that produced lactic acid fastest inhibited B. cereus best. Increased concentrations of lactic and acetic acid and carbon dioxide were also observed after co-culture with B. cereus compared to growth of the LAB strains alone, which indicates that B. cereus stimulates the biosynthetic capacities of the LAB strains.

The growth and death or survival of Bacillus cereus in sterile skimmed milk fermented with 18 different lactic acid bacteria (LAB) were investigated. B. cereus alone in milk reached about 107–108 colony-forming units (cfu)/ml. When B. cereus was cultivated together with different Lactobacillus or Lactococcus cultures at 30 or 37 °C, the B. cereus counts after 72 h of fermentation ranged between <10 cfu/ml and about 106 cfu/ml. The inhibition patterns for the different Lactobacillus and Lactococcus cultures varied. All the Lactococcus cultures (with one exception) reduced pH to 5.3 or lower in 7 h. After 24 h, B. cereus was not detected in any of the fast Lactococcus-fermented milk samples. After 48 h, B. cereus was not detected for 4 of the 12 Lactobacillus cultures. These cultures reduced pH to below 5.0 in 24 h. The other Lactobacillus cultures also inhibited B. cereus, but the counts of B. cereus were still 104–106 cfu/ml after 72 h. They also reduced pH at a slower rate. Survival of B. cereus was to a variable extent linked with formation of endospores. Proteinase K did not affect the antimicrobial activity observed. Acid production with decreasing pH, particularly the initial rate of pH decrease, appears to be most important for control of B. cereus with LAB.

A survey was conducted using a questionnaire to document the production methods of Bushera, a Ugandan traditional fermented cereal beverage, in the districts of Kabale and Rukungiri in the South Western region of Uganda. The chemical composition of raw materials and Bushera was determined using standard methods. Similarities in the production of Bushera in Kabale and Rukungiri districts were observed. In both districts, sorghum grains are usually (80% of respondents) soaked in water overnight (12 h), some households (20%) indicated a soaking period of 24-48 h. Eighty seven percent of the households soaked the grains in streams, rivers and ponds. The germination period for sorghum grains varied between two and four days. Sixty five percent of the households germinated the grains for two-three days. The duration of fermentation of Bushera ranged from one to six days. Most of the households (90%) consumed Bushera after two-four days of fermentation. The moisture, fat, protein and carbohydrate contents of germinated and non-germinated sorghum grains ranged from 8.8-12.4 %, 1.8-3.0 %, 7.2-10.8 % and 77.7-85.7%, respectively. Germinated sorghum flour had lower fat, protein and carbohydrate contents but higher ash and fibre than non-germinated sorghum flour. Germinated millet flour had higher moisture, protein and fibre compared to the non-germinated flour while the latter had higher ash and carbohydrate contents. Germination resulted in an increase in the concentration of sugars in both sorghum and millet grains. Great variations were observed in the proximate composition of Bushera obtained from the households. Under laboratory conditions, the protein content of Bushera produced from germinated grains was higher than Bushera from non-germinated grains (12.2% vs. 10.6%), on dry matter basis. Higher levels of iron, magnesium and zinc were observed in germinated grains due to addition of wood ash during germination. Germinated grains had lower phenol and tannin content compared to non-germinated grains. Résumé Une étude basée sur les réponses à un questionnaire a été menée pour documenter les méthodes de production du Bushera, une boisson de céréales fermentées traditionnelle en Ouganda, dans les districts de Kabale et Rukungiri situés dans la région sud-ouest de l'Ouganda. La composition chimique des matières premières et du Bushera a été établie par méthodes standard. On a observé des similarités dans la production du Bushera dans les districts de Kabale et de Rukungiri. Dans les deux districts, les graines de sorgho sont habituellement (80% des réponses) trempées dans de l'eau pendant une nuit (12h), certains ménages (20%) signalant une période de trempage de 24-48h.Les graines sont trempées dans des ruisseaux, rivières et étangs par 87% des ménages. La période de germination des graines de sorgho varie de 2 à 4 jours. Soixante-cinq pour cent des ménages font germer les graines pendant 2-3 jours. La durée de fermentation du Bushera va de 1 à 6 jours. La majorité des ménages (90%) consomment le Bushera après 2-4 jours de fermentation. Le contenu des graines de sorgho germées et non germées en humidité, graisses, protéines et féculents était de 8,8-12,4%; 1,8-3.0%; 7,7-10,8%; et 77,7-80,2% respectivement. La farine de sorgho germé a une moindre teneur en graisses, protéines et féculents mais une plus forte teneur en cendres et fibres que la farine de sorgho non germé. La farine de millet germé contient plus d'humidité, protéines et fibres que la farine non germée, tandis que cette dernière a une plus forte teneur en cendres et féculents. La germination entraîne une augmentation de la concentration des sucres dans les graines de sorgho et de millet. On a constaté d'importantes variations dans la composition approximative du Bushera obtenu auprès des ménages. En laboratoire, le contenu en protéines du Bushera fait de graines germées était plus élevé que dans le Bushera de graines non germées (12,2% comparé à 10,6%), sur base de matières sèches. Des niveaux plus élevés de fer, magnésium et zinc ont été observés dans les graines germées en raison de l'apport de cendres de bois pendant la germination. Les graines germées avaient une plus basse teneur en phénol et en tanin comparé aux graines non germées. (Af. J. Food Agriculture, Nutrition and Development: 2003 3(1): 10-19)

ABSTRACT In Gouda and Cheddar type cheeses the amino acid conversion to aroma compounds, which is a major process for aroma formation, is essentially due to lactic acid bacteria (LAB). In order to evaluate the respective role of starter and nonstarter LAB and their interactions in cheese flavor formation, we compared the catabolism of phenylalanine, leucine, and methionine by single strains and strain mixtures of Lactococcus lactis subsp. cremoris NCDO763 and three mesophilic lactobacilli. Amino acid catabolism was studied in vitro at pH 5.5, by using radiolabeled amino acids as tracers. In the presence of α-ketoglutarate, which is essential for amino acid transamination, the lactobacillus strains degraded less amino acids than L. lactis subsp. cremoris NCDO763 , and produced mainly nonaromatic metabolites. L. lactis subsp. cremoris NCDO763 produced mainly the carboxylic acids, which are important compounds for cheese aroma. However, in the reaction mixture containing glutamate, only two lactobacillus strains degraded amino acids significantly. This was due to their glutamate dehydrogenase (GDH) activity, which produced α-ketoglutarate from glutamate. The combination of each of the GDH-positive lactobacilli with L. lactis subsp. cremoris NCDO763 had a beneficial effect on the aroma formation. Lactobacilli initiated the conversion of amino acids by transforming them mainly to keto and hydroxy acids, which subsequently were converted to carboxylic acids by the Lactococcus strain. Therefore, we think that such cooperation between starter L. lactis and GDH-positive lactobacilli can stimulate flavor development in cheese.