The influence of protein concentration on key quality attributes of chickpea-based alternatives to cheese.

In response to consumer demands, plant protein ingredients are increasingly being used in the formulation of plant-based alternatives to cheese. The aim of this study was to determine the influence of protein concentration on key quality attributes of chickpea-based alternatives to cheese. Moreover, the age-induced changes in such attributes were assessed, with samples analysed after 1 month of storage. After characterisation of the ingredients, the chickpea-based formulations were prepared by blending chickpea flour and protein concentrate in different proportions to obtain four samples of increasing protein content (i.e., 8.68-21.5%). Formulations were developed at pH ∼4.5, and a moisture content of 50%, with shea butter used to obtain 15% fat content. The differential scanning calorimetry thermograms of the samples showed a main peak around 30 °C, corresponding to transition of the shea butter, and a smaller peak around 70 °C related to starch gelatinisation. Analysis of microstructure showed formation of a protein matrix with more extensive protein structure at high protein concentration. Furthermore, none of the chickpea-based samples melted under the testing conditions and all samples showed increasing values for adhesiveness, springiness and cohesiveness with increasing protein content. However, hardness was the highest for the sample with the lowest protein content, likely due to starch retrogradation. After storage, hardness increased further for all samples. This work improves our understanding of the role of chickpea protein in developing plant-based alternatives to cheese and the challenges therein.

Correlation analysis of protein quality characteristics with gluten-free bread properties.

The interest in gluten-free cereal products has increased significantly over the last number of years and there is still a high demand for high quality products. This study aims to establish possible connections between protein properties and dough and bread quality which could advance the knowledge for gluten-free product development. The objective of the present study was to correlate protein properties with bread characteristics. Therefore, a wide range of tests (solubility, emulsifying, foaming, water hydration properties) was performed to characterize a range of food proteins (potato, pea, carob, lupin and soy). Furthermore, the performance of these proteins in a dough matrix (pasting, rheology) and bread formulation (volume, structure, and texture) was analysed. Statistical analysis showed significant (p < 0.05) correlations between protein properties, dough properties and final bread characteristics. The addition of the proteins to the gluten-free bread formulation affected pasting rheological and bread characteristics such as crumb density, crumb hardness and specific volume. The addition of potato and soy protein resulted in the lowest volume with a dense crumb structure and a low consumer acceptance score. However, lupin, pea and carob containing gluten-free breads had a higher specific volume and softer and less dense crumb structure. The protein solubility (r, 0.89; p < 0.01) and its foaming properties (r, 0.97; p < 0.05) were found to be the most important protein properties with correlations significantly with dough properties and bread quality.

Control of Zymoseptoria tritici cause of septoria tritici blotch of wheat using antifungal Lactobacillus strains.

AIMS: This study explored an effective biological control agent based on lactic acid bacteria culture or culture supernatant, which was effective against fungicide-resistant Zymoseptoria tritici, which causes septoria tritici blotch (STB). METHODS AND RESULTS: Three lactic acid bacteria strains which exhibited broad antifungal activity were investigated for their potential to control Z. tritici. Plate assays, liquid culture growth inhibition assays and STB biocontrol seedling tests were employed. Lactobacillus brevis JJ2P and Lactobacillus reuteri R2 caused significant fungal inhibition as observed by large mycelium clearing on modified MRS agar. Cell-free culture supernatants of Lact. brevis JJ2P and Lact. reuteri R2 showed antifungal activity against Z. tritici, as observed by mycelial radial growth inhibition and liquid culture growth inhibition. Cell-free supernatants of these anti-Z. tritici LAB strains were assessed in vivo for their abilities to inhibit STB development in seedling tests. Lact. brevis JJ2P was capable of inhibiting disease development and significantly reduced the diseased leaf area covered with pycnidia. CONCLUSIONS: Biological control accomplished by beneficial micro-organisms such as Lact. brevis JJ2P may represent an alternative control strategy for reducing STB. SIGNIFICANCE AND IMPACT OF THE STUDY: Globally, STB is regarded as one of the most important diseases of wheat. Control of Z. tritici is heavily reliant on fungicide application. The recent emergence of resistance or reduced sensitivity to fungicides among Z. tritici populations has urgently called for the development of new control strategies.

Evaluation of exopolysaccharide producing Weissella cibaria MG1 strain for the production of sourdough from various flours.

This study determined exopolysaccharide (EPS) production by Weissella cibaria MG1 in sourdoughs prepared from gluten-free flours (buckwheat, oat, quinoa and teff), as well as wheat flour. Sourdoughs (SD) were fermented without sucrose, or by replacing 10% flour with sucrose to support EPS production. The amount of EPS depended on the substrate: high amounts of EPS corresponding to low amounts of oligosaccharides were found in buckwheat (4.2 g EPS/kg SD) and quinoa sourdoughs (3.2 g EPS/kg SD); in contrast, no EPS but panose-series oligosaccharides (PSO) were detected in wheat sourdoughs. Organic acid production, carbohydrates and rheological changes during fermentation were compared to the EPS negative control without added sucrose. Corresponding to the higher mineral content of the flours, sourdoughs from quinoa, teff and buckwheat had higher buffering capacity than wheat. Fermentable carbohydrates in buckwheat, teff and quinoa flours promoted W. cibaria growth; indicating why W. cibaria failed to grow in oat sourdoughs. Endogenous proteolytic activity was highest in quinoa flour; α-amylase activity was highest in wheat and teff flours. Protein degradation during fermentation was most extensive in quinoa and teff SD reducing protein peaks 18-29, 30-41 and 43-55 kDa extensively. Rheological analyses revealed decreased dough strength (AF) after fermentation, especially in sucrose-supplemented buckwheat sourdoughs correlating with amounts of EPS. High EPS production correlated with high protein, fermentable sugars (glucose, maltose, fructose), and mineral contents in quinoa flour. In conclusion, W. cibaria MG1 is a suitable starter culture for sourdough fermentation of buckwheat, quinoa and teff flour.

Barley malt wort fermentation by exopolysaccharide-forming Weissella cibaria MG1 for the production of a novel beverage.

AIMS: The growing interest of governments and industry in developing healthy and natural alternative foods and beverages that will fulfil the consumer drive towards a healthy lifestyle and clean-label, natural diet has led to an increase in traditional lactic acid bacteria fermentation research. In particular, this research aims to address the organoleptic modulation of beverages using in situ-produced bacterial polysaccharides. METHODS AND RESULTS: Weissella cibaria MG1 is capable of producing exopolysaccharides (dextran) and oligosaccharides (glucooligosaccharides) during sucrose-supplemented barley-malt-derived wort fermentation. Up to 36·4 g l(-1) of dextran was produced in an optimized system, which improved the rheological profile of the resulting fermentate. Additionally, small amounts of organic acids were formed, and ethanol remained below 0·5% (v/v), the threshold volume for a potential health claim designation. CONCLUSIONS: The results suggest that the cereal fermentate produced by W. cibaria MG1 could be potentially used for the production of a range of novel, nutritious and functional beverages. SIGNIFICANCE AND IMPACT OF THE STUDY: Using conventional raw materials and traditional processes, novel LAB-fermented beverages can be produced representing an innovative mechanism towards fulfilling the aim to decrease government and personal costs as well as potentially ameliorating consumer lifestyle regarding dietary-related disease.

Analysis of bacterial community shifts in the gastrointestinal tract of pigs fed diets supplemented with ß-glucan from Laminaria digitata, Laminaria hyperborea and Saccharomyces cerevisiae.

This study was designed to evaluate the effects of algal and yeast ß-glucans on the porcine gastrointestinal microbiota, specifically the community of Lactobacillus, Bifidobacterium and coliforms. A total of 48 pigs were fed four diets over a 28-day period to determine the effect that each had on these communities. The control diet consisted of wheat and soya bean meal. The remaining three diets contained wheat and soya bean meal supplemented with ß-glucan at 250 g/tonne from Laminaria digitata, Laminaria hyperborea or Saccharomyces cerevisiae. Faecal samples were collected from animals before feeding each diet and after the feeding period. The animals were slaughtered the following day and samples were collected from the stomach, ileum, caecum, proximal colon and distal colon. Alterations in Lactobacillus in the gastrointestinal tract (GIT) were analysed using denaturing gradient gel electrophoresis (DGGE) profiles generated by group-specific 16S rRNA gene PCR amplicons. Plate count analysis was also performed to quantify total coliforms. DGGE profiles indicated that all ß-glucan diets provoked the emergence of a richer community of Lactobacillus. The richest community of lactobacilli emerged after feeding L. digitata (LD ß-glucan). Plate count analysis revealed that the L. hyperborea (LH ß-glucan) diet had a statistically significant effect on the coliform counts in the proximal colon in comparison with the control diet. ß-glucan from L. digitata and S. cerevisiae also generally reduced coliforms but to a lesser extent. Nevertheless, the ß-glucan diets did not significantly reduce levels of Lactobacillus or Bifidobacterium. DGGE analysis of GIT samples indicated that the three ß-glucan diets generally promoted the establishment of a more varied range of Lactobacillus species in the caecum, proximal and distal colon. The LH ß-glucan had the most profound reducing effect on coliform counts when compared with the control diet and diets supplemented with L. digitata and S. cerevisiae ß-glucans.

Inhibition of growth of Trichophyton tonsurans by Lactobacillus reuteri.

AIM: The aims of this study were to identify antifungal lactic acid bacteria (LAB) and characterize their activity against the dermatophyte Trichophyton tonsurans. METHODS AND RESULTS: A total of 165 different LAB were isolated and initially screened for anti-Penicillium expansum activity. Five strains, which exhibited strong inhibitory activity, were then tested against the dermatophyte T. tonsurans DSM12285, where they also caused inhibition as observed by large fungal clearing on agar surface. The strongest inhibition was seen with Lactobacillus reuteri R2. When freeze-dried cell-free supernatant powder from this strain was incorporated in culture medium at concentrations >1%, growth of fungal colony was inhibited. Conidia germination was also inhibited under these conditions as determined by microscopy. The anti-T. tonsurans activity of Lact. reuteri R2 was not affected neither by heat treatment nor by proteolytic treatment using pronase E and proteinase K, indicating that the responsible agent(s) were nonproteinaceous in nature. CONCLUSIONS: Lactobacillus reuteri R2 was identified as having strong inhibitory activity against the dermatophyte T. tonsurans DSMZ12285. SIGNIFICANCE AND IMPACT OF THE STUDY: LAB are naturally associated with many foods and are well recognized for their biopreservative properties. The use of these and/or their products may well provide alternative safe approaches for the inhibition of dermatophytic fungi.

The use of Lactobacillus brevis PS1 to in vitro inhibit the outgrowth of Fusarium culmorum and other common Fusarium species found on barley.

A total of 129 lactic acid bacteria (LAB) were screened for antifungal activity against common Fusarium spp. isolated from brewing barley. Four out of the five most inhibiting isolates were identified as Lactobacillus brevis, whereas one belonged to Weissella cibaria. L. brevis PS1, the isolate showing the largest inhibition spectrum, was selected and the influence of its freeze-dried cell-free supernatant (cfsP) on germination of macroconidia as well as mycelia growth was investigated using Fusarium culmorum as target organism.Addition of cfsP into the growth medium at concentrations > or = 2% altered the growth morphology of F.culmorum, whereas at concentrations > 5% the outgrowth of germ tubes from macroconidia was delayed and distorted. The presence of 10% cfsP completely inhibited the outgrowth of F. culmorum macroconidia. The activity of the compounds produced by L. brevis PS1 was higher at low pH values, i.e. pH < 5. Heating and/or proteolytic treatment reduced the inhibitory activity of cfsP, indicating that L. brevis produces organic acids and proteinaceous compounds which are active against Fusarium spp.

Nutritive value and chemical composition of pseudocereals as gluten-free ingredients.

The only treatment available for patients with coeliac disease is a lifelong elimination of food products containing gluten. The gluten-free products currently available in the market are considered of low quality and poor nutritional value. In the present study, the pseudocereals amaranth, quinoa and buckwheat were studied as potential healthy ingredients for improving the nutritional quality of gluten-free breads. The pseudocereal seeds and pseudocereal-containing gluten-free breads were evaluated in terms of their protein, fat, total starch, dietary fibre, ash and mineral content as well as their fatty acid composition. The pseudocereal containing gluten-free breads showed significantly higher levels of protein, fat, fibre and minerals than the control bread. The attributes of these breads conform to the expert's nutritional recommendations for the gluten-free diet and gluten-free foods. These results suggest that the pseudocereals amaranth, quinoa and buckwheat can represent a healthy alternative to frequently used ingredients in gluten-free products.

The use of sourdough fermented by antifungal LAB to reduce the amount of calcium propionate in bread.

Addition of sourdough is a common practice in the bakery industry to improve, among other quality parameters, the shelf life of bread. In this study, sourdough fermented by antifungal Lactobacillus plantarum strains was investigated for the ability to inhibit growth of common bread spoilage fungi. In both in vitro and sourdough wheat bread system, the antifungal sourdoughs significantly affected the outgrowth of Aspergillus niger, Fusarium culmorum, or Penicillium expansum spores, however on wheat bread outgrowth of Penicillium roqueforti spores was not affected. In an attempt to reduce the amounts of chemical additives in bread, the antifungal sourdoughs were used in combination with calcium propionate (CAP) and possible synergistic effects were evaluated. Presence of 3000 ppm CAP in the bread did not affect the outgrowth of P. roqueforti, whereas outgrowth of the other fungi was retarded. A strong synergistic effect was observed when CAP and antifungal sourdoughs were combined into the bread formulation, and outgrowth of P. roqueforti was affected. The use of reduced CAP amount (1000 ppm) showed significant inhibition only when antifungal sourdough was added. Remarkably, the increase in shelf life achieved was higher than that obtained using 3000 ppm of CAP alone. In conclusion, the results of this study clearly show that the addition of antifungal sourdough has the potential to reduce the levels of chemical additives needed in the bakery industry to ensure the microbiological safety of bread.

Characterization of proteolysis during the ripening of semi-dry fermented sausages.

The respective contribution of indigenous enzymes and enzymes from starter bacteria to proteolysis in fermented sausages were determined by comparing the proteolytic changes occurring in sausages resulting from the presence of a proteolytic strain of Staphylococcus carnosus, i.e. S. carnosus MC 1 to the proteolytic changes occurring in control sausages containing glucono-δ-lactone (GDL) and an antibiotic mixture. Proteolysis was quantified by assaying for non-protein nitrogen (NPN) and free amino acids. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and reversed phase high performance liquid chromatography (RP-HPLC) were used to qualitatively assess the proteolytic changes in the sarcoplasmic and myofibrillar proteins as ripening progressed. The concentration of NPN and free amino acids increased in both sausages initially, but subsequently decreased towards the end of ripening in sausages inoculated with the starter culture. SDS-PAGE showed a similar pattern of proteolysis of sarcoplasmic proteins in both sausages, while of the two sausage types; the S. carnosus MC 1 inoculated sausages exhibited the most intense degradation of myofibrillar proteins, especially myosin and actin. RP-HPLC profiles of 2% trichloroacetic acid (TCA)-soluble peptides for the two sausage types were similar, with the production of numerous hydrophilic peptides. N-Terminal amino acid sequence analysis and sequence homology with proteins of known primary structure showed that six of the TCA-soluble peptides were released from the sarcoplasmic (myoglobin and creatine kinase) and myofibrillar (troponin-I, troponin-T and myosin light chain-2) proteins. In addition, the initial degradation of sarcoplasmic proteins was due to the activity of indigenous proteinases, while both indigenous and bacterial enzymes contributed to the initial degradation of myofibrillar proteins. Furthermore, indigenous enzymes were responsible for the release of TCA-soluble peptides, which, were further hydrolysed by bacterial enzymes.

Pre-inoculation enrichment procedure enhances the performance of bacteriocinogenic Lactococcus lactis meat starter culture.

Sodium nitrite and sodium chloride may inhibit growth and bacteriocinogenesis of protective starter cultures. To reduce sensitivity of a lacticin 3147-producing starter culture to nitrite, prior to production of salami, Lactococcus lactis DPC 4275 was placed in a number of pre-inoculation treatments, containing (a) 1% glucose, (b) 2.5 ppm manganese (Mn), (c) 250 ppm magnesium (Mg), (d) 2.5 ppm manganese + 250 ppm magnesium (Mn + Mg), and held at ambient temperature for 30 min and 4 degrees C for 2 h. The growth, pH reduction, and bacteriocin production was monitored in beaker sausage over a period of 10 days at 28 degrees C, corresponding to typical salami production time, and compared to untreated starter culture. The effect of 1% tryptone and inoculum level on growth and bacteriocin production was also determined. Challenge tests were performed using Listeria innocua DPC 1770 and Staphylococcus aureus MMPR3 as target strains. All treatments gave a significantly higher (P < 0.05) initial starter level than the untreated starter. Beaker sausage inoculated with either low (10(7)) or high (10(9)) levels of starter culture, treated with Mn + Mg reached significantly (P < 0.05) higher levels by day 10 than other treatments. Trends indicate that Mn + Mg also gave best pH reduction in sausage containing the low-level starter culture, sausage and significantly lower (P < 0.05) values for sausage produced with higher inoculum. Bacteriocin production was also higher in starter culture treated with Mn, or glucose. Pre-treatment with Mg gave a 2-fold increase in bacteriocin, the addition of Mn augmenting this increase further. The incorporation of tryptone gave no additional effect. In beaker sausage, both L. innocua and S. aureus populations showed significant reductions (P < 0.05) in the presence of the bacteriocinogenic strain compared to a non-bacteriocinogenic control strain.

Continuous production of lacticin 3147 and nisin using cells immobilized in calcium alginate.

Bacteriocinogenic strains, Lactococcus lactis subsp. lactis DPC 3147 and L. lactis DPC 496, producing lacticin 3147 and nisin, respectively, were immobilized in double-layered calcium alginate beads. These beads were inoculated into MRS broth at a ratio of 1:4 and continuously fermented for 180 h. Free cells were used to compare the effect of immobilization on bacteriocin production. After equilibrium was reached, a flow rate of 580 ml h(-1) was used in the immobilized cell (IC), and 240 ml h(-1) in free-cell (FC) bioreactors. Outgrowth from beads was observed after 18 h. Bacteriocin production peaked at 5120 AU ml(-1) in both IC and FC bioreactors. However, FC production declined after 80 h to 160 AU ml(-1) at the end of the fermentation. Results of this study indicate that immobilization offers the possibility of a more stable and long-term means of producing lacticin 3147 in laboratory media than with free cells.

An effective lacticin biopreservative in fresh pork sausage.

Lacticin 3147 is a novel heat-stable bacteriocin, produced by Lactococcus lactis DPC 3147, that exhibits a broad-range inhibition spectrum similar to nisin. In this study, the effect of lacticin 3147 and nisin on the shelf life of fresh pork sausage and their ability to control pathogens (Clostridium perfringens DSM 756, Salmonella Kentucky AT1) and nonpathogenic Listeria innocua DPC 1770 was investigated. The following preservative regimens were evaluated, both in broth and sausage systems: (i) 450 ppm of sodium metabisulphite; (ii) 500 IU g(-1) or ml(-1) of nisin, (iii) 2500 arbitary units (AU) g(-1) or ml(-1) of lacticin 3147; (iv) 2% sodium lactate and 500 IU of nisin; (v) 2% sodium citrate and 500 IU g(-1) or ml(-1) of nisin; (vi) 2% sodium lactate and 2500 AU g(-1) or ml(-1) of lacticin 3147, (vii) 2% sodium citrate and 2500 AU g(-1) or ml(-1) of lacticin 3147, (viii) 2% sodium lactate, and (ix) 2% sodium citrate. There was no significant difference in the activity of nisin and lacticin 3147 against any of the target strains used, both bacteriocins performing significantly better than sodium metabisulfite against gram-positive strains in broth systems. Trends indicate that the combination of organic acids with either bacteriocin enhanced its activity against Salmonella Kentucky and L. innocua and was particularly effective in the inhibition of C. perfringens in fresh pork sausage. In addition, lacticin 3147 combined with either sodium citrate or sodium lactate maintained significantly lower (P < 0.05) total aerobic plate counts for the duration of the trials and may function as an alternative to sodium metabisulfite in the preservation of fresh pork sausage.

Use of two-dimensional electrophoresis to evaluate proteolysis in salmon (Salmo salar) muscle as affected by a lactic fermentation.

Two-dimensional electrophoresis was used to study proteolysis in salmon fillets inoculated or not with the starter culture Lactobacillus sake LAD. Protein fragments appeared increasingly with time in both samples, indicating that the main quantitative changes were due to endogenous enzymes. In the most acidic zone (pI = 4-6. 20) particularly, proteolysis was overall independent from processing. In contrast, fermentation had a significant effect in the pH range 6.20-8.35, suggesting a specificity of the bacterial proteases of L. sake toward alkaline to slightly acidic proteins. Furthermore, fragments surrounding tropomyosin (apparent pI = 4.70) appeared in fermented samples, indicating that the protein may be a suitable substrate for the metabolism of L. sake LAD.

Reduced nitrite levels and dietary α-tocopheryl acetate supplementation: effects on the colour and oxidative stability of cooked hams.

The objective of the present study was to determine the effects of dietary vitamin E supplementation and reduced nitrite levels on the colour stability of cooked hams. Large white × Landrace pigs (male n=6, female n=6) were each subdivided into two groups (n=3) and fed an α-tocopheryl acetate supplemented diet (1000 mg/kg feed) and a basal diet (10 mg/kg feed) for a period of 10 weeks. M. semitendinosus were removed from each pig, divided into light and dark pigmented fractions, vacuum packed and stored at 4°C for 24 h. Muscles were cured with input nitrite levels of 25 and 100 mg/kg meat and were tumbled and massaged for 17 h. Samples were cooked, sliced and overwrapped in a high oxygen permeable film for a storage period of 10 days. Surface colour of hams was measured and expressed as Hunter 'a' values. Concentrations of α-tocopherol were significantly (P<0.001) greater in supplemented muscles compared to basal muscles for both male and female pigs. Hams manufactured from male and female supplemented pigs resulted in significantly (P<0.001) higher Hunter 'a' values than hams manufactured from male and female pigs receiving the basal diet. Muscles cured with 100 mg nitrite/kg meat formed products with significantly (P<0.001) higher 'a' values than those cured with the lower (25 mg/kg meat) nitrite level. Hams manufactured from supplemented muscles, treated with 25 mg nitrite/kg meat showed significantly (P<0.05) higher Hunter 'a' values than hams manufactured from basal muscles, treated with 100 mg nitrite/kg meat. Hams manufactured from female porcine muscles had significantly (P<0.001) higher 'a' values than hams from male muscles during the 10 days of simulated retail display. No such gender differences were observed for TBARS values.

Effect of Dietary Supplementation with α-Tocopheryl Acetate on the Stability of Reformed and Restructured Low Nitrite Cured Turkey Products.

The objective of this study was to investigate the effects of sodium (Na) nitrite reduction on the oxidative and colour stability of reformed and restructured cured cooked turkey products manufactured from meat containing high and low levels of dietary α-tocopheryl acetate. Turkeys were randomly assigned to either a control group, fed a basal α-tocopheryl acetate diet (20mg/kg feed), or a treatment group fed a supplemented α-tocopheryl acetate diet (600mg/kg feed). Diets were fed ad libitum from day 1 until slaughter on day 147. Breast meat from control and treatment groups was used to manufacture cured reformed cooked turkey ham and cured restructured cooked turkey patties. Residual levels of 60 and 120mg Na nitrite/kg of meat were used. Turkey products were packaged in either overwrap or vacuum packaging and stored under refrigerated (4°C) illuminated display for 10 days. Results showed that dietary supplementation with α-tocopheryl significantly (p<0·05) improved the oxidative and colour stability of all low nitrite products produced when compared to non-supplemented controls.

Determination of the influence of organic acids and nisin on shelf-life and microbiological safety aspects of fresh pork sausage.

The effect of replacing sulphur dioxide with organic acids and nisin to reduce the microbial counts in fresh pork sausage was examined. The potential of sodium citrate or sodium lactate, used singly or in combination with nisin, was also assessed in sausage inoculated with Staphylococcus aureus MMPR 3 and Salmonella kentucky AT 1. The results indicate that a combination of sodium lactate and nisin wa particularly effective in reducing total bacterial counts in this food product. It also appears that this combination provides an increased protection against common pathogenic contaminants of fresh pork sausage, i.e. Staph. aureus and Salmonella species.

Method for the rapid quantitative detection of lipolytic activity among food fermenting microorganisms.

A standard method for the detection of free fatty acids (FFAs) in milk was modified and applied to the measurement of the lipolytic activity of microorganisms in a model system containing either homogenised pork or beef fat tissue. The increase in FFAs was measured colorimetrically using palmitic acid as a standard. Among the strains tested, two strains of Staphylococcus xylosus and one strain of Staphylococcus carnosus were found to display lipolytic activity. For all strains, a higher increase in FFA was observed in broth supplemented with pork fat than with beef fat. All three strains displayed lipolytic activity when tested on tributyrin agar plates.

A modified agar medium for the screening of proteolytic activity of starter cultures for meat fermentation purposes.

An agar medium, used in the screening of proteolytic activity of dairy-related bacteria, was adapted for assessing the proteolytic capacity of bacteria which were of possible use in meat fermentations. Freeze dried myofibrils, extracted from pork muscle, were incorporated in the medium. The agar plates were inoculated with 20 microl of overnight cultures of different starter strains, and incubated at 30 degrees C for 48 h. After incubation, proteolytic bacteria produced clear zones. Coomassie brilliant blue stain was employed to facilitate the detection of these zones. Proteolytic activity was confirmed in an enzymatic test.