Microbial decontamination assisted by ultrasound-based processing technologies in food and model systems: A review.

Ultrasound (US) technology is recognized as one of the emerging technologies that arise from the current trends for improving nutritional and organoleptic properties while providing food safety. However, when applying the US alone, higher power and longer treatment times than conventional thermal treatments are needed to achieve a comparable level of microbial inactivation. This results in risks, damaging food products' composition, structure, or sensory properties, and can lead to higher processing costs. Therefore, the US has often been investigated in combination with other approaches, like heating at mild temperatures and/or treatments at elevated pressure, use of antimicrobial substances, or other emerging technologies (e.g., high-pressure processing, pulsed electric fields, nonthermal plasma, or microwaves). A combination of US with different approaches has been reported to be less energy and time consuming. This manuscript aims to provide a broad review of the microbial inactivation efficacy of US technology in different food matrices and model systems. In particular, emphasis is given to the US in combination with the two most industrially viable physical processes, that is, heating at mild temperatures and/or treatments at elevated pressure, resulting in techniques known as thermosonication, manosonication, and manothermosonication. The available literature is reviewed, and critically discussed, and potential research gaps are identified. Additionally, discussions on the US's inactivation mechanisms and lethal effects are included. Finally, mathematical modeling approaches of microbial inactivation kinetics due to US-based processing technologies are also outlined. Overall, this review focuses only on the uses of the US and its combinations with other processes relevant to microbial food decontamination.

High-pressure processing of meat: Molecular impacts and industrial applications.

High-pressure processing (HPP) has been the most adopted nonthermal processing technology in the food industry with a current ever-growing implementation, and meat products represent about a quarter of the HPP foods. The intensive research conducted in the last decades has described the molecular impacts of HPP on microorganisms and endogenous meat components such as structural proteins, enzyme activities, myoglobin and meat color chemistry, and lipids, resulting in the characterization of the mechanisms responsible for most of the texture, color, and oxidative changes observed when meat is submitted to HPP. These molecular mechanisms with major effect on the safety and quality of muscle foods are comprehensively reviewed. The understanding of the high pressure-induced molecular impacts has permitted a directed use of the HPP technology, and nowadays, HPP is applied as a cold pasteurization method to inactive vegetative spoilage and pathogenic microorganisms in ready-to-eat cold cuts and to extend shelf life, allowing the reduction of food waste and the gain of market boundaries in a globalized economy. Yet, other applications of HPP have been explored in detail, namely, its use for meat tenderization and for structure formation in the manufacturing of processed meats, though these two practices have scarcely been taken up by industry. This review condenses the most pertinent-related knowledge that can unlock the utilization of these two mainstream transformation processes of meat and facilitate the development of healthier clean label processed meats and a rapid method for achieving sous vide tenderness. Finally, scientific and technological challenges still to be overcome are discussed in order to leverage the development of innovative applications using HPP technology for the future meat industry.

Aspects of high hydrostatic pressure food processing: Perspectives on technology and food safety.

The last two decades saw a steady increase of high hydrostatic pressure (HHP) used for treatment of foods. Although the science of biomaterials exposed to high pressure started more than a century ago, there still seem to be a number of unanswered questions regarding safety of foods processed using HHP. This review gives an overview on historical development and fundamental aspects of HHP, as well as on potential risks associated with HHP food applications based on available literature. Beside the combination of pressure and temperature, as major factors impacting inactivation of vegetative bacterial cells, bacterial endospores, viruses, and parasites, factors, such as food matrix, water content, presence of dissolved substances, and pH value, also have significant influence on their inactivation by pressure. As a result, pressure treatment of foods should be considered for specific food groups and in accordance with their specific chemical and physical properties. The pressure necessary for inactivation of viruses is in many instances slightly lower than that for vegetative bacterial cells; however, data for food relevant human virus types are missing due to the lack of methods for determining their infectivity. Parasites can be inactivated by comparatively lower pressure than vegetative bacterial cells. The degrees to which chemical reactions progress under pressure treatments are different to those of conventional thermal processes, for example, HHP leads to lower amounts of acrylamide and furan. Additionally, the formation of new unknown or unexpected substances has not yet been observed. To date, no safety-relevant chemical changes have been described for foods treated by HHP. Based on existing sensitization to non-HHP-treated food, the allergenic potential of HHP-treated food is more likely to be equivalent to untreated food. Initial findings on changes in packaging materials under HHP have not yet been adequately supported by scientific data.

The evaluation of a stepped care approach for early intervention of borderline personality disorder.

BACKGROUND: The current study evaluated the stepped care approach applied in AtR!Sk; a specialized outpatient clinic for adolescents with BPD features that offers a brief psychotherapeutic intervention (Cutting Down Program; CDP) to all patients, followed by a more intensive Dialectical Behavioral Therapy for Adolescents (DBT-A) for those whose symptoms persist. METHODS: The sample consisted of 127 patients recruited from two AtR!Sk clinics. The number of BPD criteria, psychosocial functioning, severity of overall psychopathology, number of days with non-suicidal self-injury (NSSI; past month), and the number of suicide attempts (last 3 months) were assessed at clinic entry (T0), after CDP (T1), and at 1- and 2-year follow-up (T2, T3). Based on the T1 assessment (decision criteria for DBT-A: ≥ 3 BPD criteria & ZAN-BPD ≥ 6), participants were allocated into three groups; CDP only (n = 74), CDP + DBT-A (eligible and accepted; n = 36), CDP no DBT-A (eligible, but declined; n = 17). RESULTS: CDP only showed significantly fewer BPD criteria (T2: ß = 3.42, p < 0.001; T3: ß = 1.97, p = 0.008), higher levels of psychosocial functioning (T2: ß = -1.23, p < 0.001; T3: ß = -1.66, p < 0.001), and lower severity of overall psychopathology (T2: ß = 1.47, p < 0.001; T3: ß = 1.43, p = 0.002) over two years compared with CDP no DBT-A, while no group differences were found with regard to NSSI and suicide attempts. There were no group differences between CDP + DBT-A and CDP no DBT-A, neither at T2 nor at T3. DISCUSSION: The findings support the decision criterion for the offer of a more intense therapy after CDP. However, there was no evidence for the efficacy of additional DBT-A, which might be explained by insufficient statistical power in the current analysis.

Pre-Treatment of Starter Cultures with Mild Pulsed Electric Fields Influences the Characteristics of Set Yogurt.

The aim of this study was to investigate the effect of pulsed electric field (PEF) pre-treatment of a dairy starter culture of Lactobacillus delbrueckii subsp. bulgaricus LB186 and Streptococcus thermophilus ST504 on the fermentation and final product characteristics of set-style yogurt. The effects of PEF treatment parameters, voltage (4-20 kV), pulse number (20-80 pulses), frequency (1-21 Hz), and pulse (5-8 µs) width on pH development, cell counts, and proteolytic activity, as well as on texture and degree of syneresis in yogurt were investigated by use of a two-level full factorial design. Pulse frequency and pulse width had a significant effect on the yogurt stiffness (p < 0.05) and the interaction of voltage and frequency had a significant effect on both stiffness and proteolytic activity (p < 0.05). Further experiments confirmed that pre-treatment of the dairy culture with specific PEF parameters immediately before addition to milk could accelerate fermentation of, increase stiffness of, and reduce syneresis in the final yogurt. This effect of the PEF-pre-treated culture was partially retained even after flash-freezing and 14 days of storage of the culture at -20 °C. The effects were attributed to responses to oxidative stress induced by the PEF pre-treatment.

Metabolic and microbial analyses of the surface and inner part of wet-aged and dry-aged beef.

The effects of aging and microbial growth on the metabolome of aged beef were investigated in this study. The metabolome of beef is influenced by the aging method applied. This includes the aging-related changes in metabolism and the presence of microorganisms on the beef during aging that may affect the beef and its quality. The inner part and the trimmed surface of dry-aged (the surface of dry-aged beef is also called the "crust" due to its drying during aging) and wet-aged beef were analyzed by 1 H nuclear magnetic resonance (NMR) spectroscopy over aging periods up to 28 days at intervals of 7 days, and the former also by microbiological analysis. The metabolome detected by 1 H NMR spectroscopy demonstrated changes over the aging time of beef and differed depending on the sampling location (surface or inner part of beef). The influence of the microbiota on changes in the metabolome can be negligible due to the low microbial growth on the surface of dry-aged beef (<3 log CFU/g). Therefore, the aging-related metabolism postmortem of the analyzed dry-aged beef might be the main factor for metabolic changes. The significantly (p < 0.05) higher amino acids and inosine concentrations and lower inosine 5'-monophosphate concentrations suggested enhanced protein degradation and energy metabolism in the wet-aged beef compared to the dry-aged beef, probably due to the combined influence of the aging and the microbiota on the wet-aged beef and, thus, its metabolic changes.

Cryptococcus thermophilus sp. nov., isolated from cassava sourdough.

A novel anamorphic yeast, strain LTH 6662(T), was isolated from cassava sourdough. The isolate supposedly originated from cassava flour or was a contaminant thereof. Sequencing of the D1/D2 domain of the 26S rRNA gene indicated that strain LTH 6662(T) represents a novel species. Its closest relatives were members of the Cryptococcus humicola complex. The novel strain had several physiological characteristics that differed from those of related species: the ability to assimilate raffinose and cadaverine; the inability to assimilate soluble starch, xylitol, galactitol, butane-2,3-diol, sodium nitrite and lysine; the ability to grow without vitamins and at 42 °C; and the inability to produce starch-like substances. Its major ubiquinone was Q-10. In addition, buds were formed on small neck-like structures. In liquid medium, green or blue fluorescent substances were produced. The name Cryptococcus thermophilus sp. nov. is proposed, with LTH 6662(T) (=DSM 19443(T)=CBS 10687(T)) as the type strain.

The effect of production parameters on the spatial distribution of bacterial cells in the sausage meat matrix.

In this work, the effect of processing conditions created with common meat technology equipment, on the spatial distribution of a green fluorescent protein producing -Escherichia coli in sausage meat was evaluated using confocal fluorescence microscopy and expressed with the help of the dispersion index. The results indicated that the reduction in mean particle size by prolonged comminution improved the distribution of cells in the sausage meat. Furthermore, higher fat content seemed to favor a random distribution, although not significantly. Independent of the any variation of the sausage meat production parameters, Listeria monocytogenes was effectively controlled in fermented sausages, although a theoretically less homogenous distribution of the starter culture in the sausage meat, tended to improve the effect, however, insignificantly. An early onset of the quorum-sensing-driven bacteriocin production in poorly distributed larger colonies may have been the reason for this. No differences in the composition of the microbiome between sausages with poor and good distribution of the starter culture were observed.

Impact of ecological factors on the stability of microbial associations in sourdough fermentation.

The limits for the stability of the microbial association 1 (Lactobacillus sanfranciscensis and Candida humilis) and association 2 (Lactobacillus reuteri, Lactobacillus johnsonii and Issatchenkia orientalis) during sourdough fermentation were evaluated by investigating the effects of the ecological factors substrate, refreshment time, temperature, amount of backslopping and competing species in different combinations on their growth. Sourdoughs were fermented in 28 batches under different conditions using the associations and possible competing strains as starters. The dominating microbiota was characterized by bacteriological culture, rRNA gene sequence analysis and RAPD-PCR. Association 1 was found to be competitive in doughs with rye and wheat flour at temperatures between 20 and 30 °C, refreshment times of 12 and 24 h, amounts of backslopping dough from 5 to 20% and against all competing lactic acid bacteria and yeasts. The processing parameters for the competitiveness of the association 2 were temperatures of 35-40 °C, refreshment times of 12-24 h and the substrates rye bran, wheat and rye flour, but not in every case. Issatchenkia orientalis could only grow when enough oxygen was available. Its cell counts fell rapidly under the limit of detection when using high amounts of doughs (small ratio of surface to volume) and refreshment times of 12 h. In conclusion, the results demonstrated that the two associations were remarkably stable under most of the investigated process conditions.

Surrogate for Electron Beam Inactivation of Salmonella on Pumpkin Seeds and Flax Seeds.

ABSTRACT: This study aimed to identify a suitable nonpathogenic surrogate for industrial validation of irradiation process by high-energy electron beam (5 MeV) of dried seeds. Pumpkin seeds (Cucurbita pepo var. styriaca) and golden flax seeds (Linum usitatissimum) were contaminated with a five-strain Salmonella cocktail comprising five serovars or a two-strain Escherichia coli cocktail comprising pathogenic strains, including E. coli O157:H7. Comparison of log survival fractions of the E. coli and Salmonella cocktails revealed that on both types of seeds, the Salmonella cocktail exhibited higher tolerance against high-energy electron beam at doses of 4 kGy than the E. coli cocktail, with a log survival fraction of -4.1 ± 0.7 compared with -6.0 ± 0.2 on pumpkin seeds and -4.7 ± 0.7 compared with reduction from 1.8 × 108 CFU/g to below the limit of detection (1 × 102 CFU/g) on flax seeds. For surrogate selection, the Salmonella cocktail and the strains E. coli DSM 18039 (strain MG1655) and Enterococcus faecium NCCB 86023 (strain NRRL B-2354) were subjected to electron beam processing at doses of 2 to 6 kGy. The calculated D10-values of the Salmonella cocktail were not significantly different (P > 0.05) from those of E. coli DSM 18039, i.e., 1.07 ± 0.10 kGy compared with 1.20 ± 0.07 kGy on pumpkin seeds and 0.88 ± 0.04 kGy compared with 1.07 ± 0.03 kGy on flax seeds. E. faecium NCCB 86023 exhibited significantly higher tolerance on pumpkin seeds (3.07 ± 0.18 kGy) and on flax seeds (2.22 ± 0.29 kGy), ∼3 log and 2 log higher than the Salmonella cocktail, respectively. Hence, the nonpathogenic E. coli DSM 18039 is suggested to serve as a surrogate for Salmonella in industrial validation trials. Because on both types of seeds E. faecium NCCB 86023 showed significantly higher tolerance against electron beam than the Salmonella cocktail, this nonpathogenic strain could serve as a process control indicator for the decontamination of dried seeds by electron beam.

Repression of the locus of the enterocyte effacement-encoded regulator of gene transcription of Escherichia coli O157:H7 by Lactobacillus reuteri culture supernatants is LuxS and strain dependent.

Culture supernatants of Lactobacillus reuteri ATCC 55730 repressed ler expression in Escherichia coli O157:H7 cells, but neither the strain's isogenic luxS mutant nor the L. reuteri 100-23C wild-type strain and its luxS mutant elicited a comparable effect. Furthermore, the epinephrine-mediated induction of ler expression was repressed by secreted substance(s) of L. reuteri ATCC 55730.

Global transcriptional response of Lactobacillus reuteri to the sourdough environment.

Lactobacillus reuteri is a lactic acid bacterium that is highly adapted to the sourdough environment. It is a dominant member of industrial type II sourdoughs, and is also able to colonize the intestinal tract of mammals, including humans, and birds. In this study, the transcriptional response of L. reuteri ATCC 55730 was investigated during sourdough fermentation by using whole-genome microarrays. Significant changes of mRNA levels were found for 101 genes involved in diverse cellular processes, such as carbohydrate and energy metabolism, cell envelope biosynthesis, exopolysaccharide production, stress responses, signal transduction and cobalamin biosynthesis. The results showed extensive changes of the organism's gene expression during growth in sourdough as compared with growth in chemically defined medium, and, thus, revealed pathways involved in the adaptation of L. reuteri to the ecological niche of sourdough. The utilization of starch and non-starch carbohydrates, the remodelling of the cell wall, characterized by reduced D-alanylation, and increased amounts of cell wall-associated polysaccharides, as well as the regulatory function of two component systems for cell wall biogenesis and metabolism were suggested by the gene expression data as being important for growth in sourdough. The impact of several L. reuteri genes for effective growth in sourdough was shown by implementation of mutant strains in sourdough fermentation. This study contributes to the understanding of the molecular fundamentals of L. reuteri's ecological competitiveness, and provides a basis for further exploration of genetic traits involved in adaptation to the food environment.

Antibiotic resistance of coagulase-negative staphylococci associated with food and used in starter cultures.

The resistance of 330 coagulase-negative staphylococci (CNS) associated with food or used in starter cultures and belonging to the species Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus piscifermentans, Staphylococcus equorum, Staphylococcus succinus and Staphylococcus xylosus, against 21 antibiotics was determined using the disk diffusion method. The incidence and number of resistances was found to be species and source of isolation dependent. Most strains of S. equorum (63%), S. succinus (90%) and S. xylosus (95%) exhibited resistances against up to seven antibiotics, whereas only few strains of S. carnosus (12%) and S. piscifermentans (27%) were antibiotic resistant. Resistances to lincomycin, penicillin, fusidic acid, oxacillin, ampicillin and tetracycline were predominant. Among strains of S. xylosus, the incidence of resistance ranged from 22% for tetracycline up to 69% for penicillin. Concerning the source of isolation, resistances were often determined in strains of S. equorum, S. succinus and S. xylosus isolated from cheese (87%) and sausage (83%), and strains of S. xylosus obtained from meat starter cultures (93%). Remarkably, all CNS were sensitive to the clinically important antibiotics chloramphenicol, clindamycin, cotrimoxazol, gentamicin, kanamycin, linezolid, neomycin, streptomycin, synercid and vancomycin. The phenotypic resistances to beta-lactam antibiotics, lincomycin and tetracycline were verified by PCR amplification and could be traced back to the genes blaZ, lnuA and tetK, respectively. This study permitted a comprehensive insight into the incidence of antibiotic resistances in food-associated CNS.

Characterization of toxin production of coagulase-negative staphylococci isolated from food and starter cultures.

In this study a comprehensive analysis of toxin production of food associated coagulase-negative staphylococci (CNS) was investigated. The strains belong to the following staphylococcal species, Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus equorum, Staphylococcus piscifermentans, Staphylococcus succinus, and Staphylococcus xylosus, which were isolated from fermented food and starter cultures. A collection of 330 strains were analyzed with respect to their hemolytic activity. 59% of the strains exhibited weak to moderate hemolytic activity with human blood and 34% with sheep blood after 48 h incubation. A selection of 35 strains were tested by immunoblot analysis for their ability to produce toxins, such as the most common staphylococcal enterotoxins (SEs), the toxic shock syndrome toxin 1 (TSST-1), and the exfoliative toxin A (ETA). 18 of the 35 strains produced at least one of the toxins with the SED and SEH being the most common. These indicate that the use of CNS in food production demands a safety evaluation.

Use of Lactobacillus strains to start cassava fermentations for Gari production.

Two Lactobacillus strains, Lactobacillus plantarum BFE 6710 and Lactobacillus fermentum BFE 6620, were used to start cassava fermentations in a pilot study under field production conditions in Kenya, to determine their potential to establish themselves as predominant lactobacilli during the fermentation. Predominant strains from three fermentations were isolated throughout the 48 h fermentation period. The use of these strains in high numbers clearly resulted in 1 to 2 log higher lactic acid bacteria (LAB) counts over the course of the fermentation when compared to the uninoculated control. 178 predominant LAB isolates were grouped based on their phenotypic characteristics, and were characterised to strain level by RAPD-PCR, followed by PFGE strain typing. Overall, L. plantarum strains represented the majority of the isolates, followed by Weissella confusa and Lactococcus garvieae strains. The results of RAPD-PCR and PFGE strain typing techniques indicated that L. plantarum BFE 6710 was successful in asserting itself as a predominant strain. In contrast, L. fermentum BFE 6620 failed to establish itself as a predominant organism in the fermentation. The success of the L. plantarum strains to predominate in the cassava fermentation demonstrates the potential for development of Lactobacillus starter cultures to industrialise the Gari production process.

Characterization of the cultivable microbiota of sprouts and their potential for application as protective cultures.

The microbiota of ten seeds and ready-to-eat sprouts produced thereof was characterized by bacteriological culture and denaturing gradient gel electrophoresis (DGGE) of amplified DNA fragments of the 16S rRNA gene. The predominant bacterial biota of hydroponically grown sprouts mainly consisted of enterobacteria, pseudomonades and lactic acid bacteria (LAB). For adzuki, alfalfa, mung bean, radish, sesame and wheat, the ratio of these bacterial groups changed strongly in the course of germination, whereas for broccoli, red cabbage, rye and green pea the ratio remained unchanged. Within the pseudomonades, Pseudomonas gesardii and Pseudomonas putida have been isolated and strains of the potentially pathogenic species Enterobacter cancerogenes and Pantoea agglomerans were found as part of the main microbiota on hydroponically grown sprouts. In addition to the microbiota of the whole seedlings, the microbiota of root, hypocotyl and seed leafs were examined for alfalfa, radish and mung bean sprouts. The highest and lowest total counts for aerobic bacteria were found on seed leafs and hypocotyls, respectively. On the other hand, the highest numbers for LAB on sprouts were found on the hypocotyl. When sprouting occurred under the agricultural conditions, e.g. in soil, the dominating microbiota changed from enterobacteria to pseudomonades for mung beans and alfalfa sprouts. No pathogenic enterobacteria have been isolated from these sprout types. Within the pseudomonades group, Pseudomonas jessenii and Pseudomonas brassicacearum were found as dominating species on all seedling parts from soil samples. In practical experiments, a strain of P. jessenii was found to exhibit a potential for use as protective culture, as it suppresses the growth of pathogenic enterobacteria on ready-to-eat sprouts.

Suitability of different construction materials for use in aseptic processing environments decontaminated with gaseous hydrogen peroxide.

The purpose of this study is to examine the behavior of different materials towards the microbial inactivation kinetic of gaseous hydrogen peroxide. Samples of 49 materials potentially used in aseptic processing environments were inoculated with 106 spores of Geobacillus stearothermophilus ATCC #12980 and exposed to defined periods using a reproducible hydrogen peroxide bio-decontamination cycle. The inactivation characteristic of each material was investigated by means of repeated D-value calculations. The results demonstrate that different materials show highly variable performance regarding the inactivation pattern of spores on each particular surface. Not only the chemical composition of the material but also differences in manufacturing processes and surface treatments were found to have an effect on the resistance of the test organisms. From the data obtained it is concluded that some correlation exists between the calculated D-values and roughness as well as wettability of the materials. Best- and worst-case materials were identified, and the dependence of specific decontamination characteristics on material properties was investigated. It is suggested to integrate studies regarding the inactivation characteristics of incorporated materials into the construction process of new aseptic processing systems bio-decontaminated with hydrogen peroxide.

Oral cavity as natural reservoir for intestinal lactobacilli.

Ecological studies indicate that most Lactobacillus species found in the human gastrointestinal tract are likely to be transient (allochthonous), originating from either the oral cavity or food. In order to investigate if oral lactobacilli constitute a part of the faecal Lactobacillus biota, the Lactobacillus biota of saliva and faeces of three human subjects were investigated and compared at two time-points in a 3-months interval. Bacteriological culture, performed by incubation under standard (37 degrees C, anaerobic) and alternative (30 degrees C, microaerobic) conditions, as well as PCR-DGGE with group-specific primers were used to characterize the predominant lactobacilli. Cell counts varied among the subjects and over time, reaching up to 10(7)CFU/ml in saliva and 5 x 10(6)CFU/g in faecal samples. The species composition of the Lactobacillus biota of human saliva and faeces was found to be subject-specific and fluctuated to some degree, but the species Lactobacillus gasseri, Lactobacillus paracasei, Lactobacillus rhamnosus and Lactobacillus vaginalis were detected at both time-points in saliva and faecal samples of individual subjects. RAPD-PCR analysis indicated that several strains of these species were present both in the oral cavity and in the faecal samples of the same subject. Oral isolates of the species L. gasseri and L. vaginalis showing identical RAPD types were found to persist over time, suggesting that these species are autochthonous to the oral cavity. Our results together with recent published data give strong evidence that some lactobacilli found in human faeces are allochthonous to the intestine and originate from the oral cavity.

Diversity and technological properties of predominant lactic acid bacteria from fermented cassava used for the preparation of Gari, a traditional African food.

Traditional fermentation of cassava is dominated by a lactic acid bacteria (LAB) population. Fermentation is important for improving product flavour and aroma as well as safety, especially by reduction of its toxic cyanogenic glucosides. The production of Gari from cassava in Benin typically occurs on a household or small industrial scale, and consequently suffers from inconsistent product quality and may not always be safe for consumption. Therefore, the diversity of LAB from a typical cassava fermentation for the preparation of Gari, and their technologically relevant characteristics were investigated with a view towards selection of appropriate starter cultures. A total of 139 predominant strains isolated from fermenting cassava were identified using phenotypic tests and genotypic methods such as rep-PCR and RAPD-PCR. DNA-DNA hybridisation and sequencing of the 16S rRNA genes were done for selected strains. Lactobacillus plantarum was the most abundantly isolated species (54.6% of isolates), followed by Leuconostoc fallax (22.3%) and Lactobacillus fermentum (18.0%). Lactobacillus brevis, Leuconostoc pseudomesenteroides and Weissella paramesenteroides were sporadically isolated. The L. plantarum strains were shown to be better acid producers and capable of faster acid production than the L. fallax or L. fermentum strains. The incidence of beta-glucosidase (linamarase) activity was also highest among strains of this species. Production of antagonistic substances such as H2O2 and bacteriocins, however, was more common among L. fallax and L. fermentum strains. Strains of all three species were capable of utilising the indigestible sugars raffinose and stachyose. Therefore, a starter culture containing a mixture of strains from all three species was recommended.

Characterization of in vitro antifungal activities of small and American cranberry (Vaccinium oxycoccos L. and V. macrocarpon Aiton) and lingonberry (Vaccinium vitis-idaea L.) concentrates in sugar reduced fruit spreads.

In this study, cranberry and lingonberry concentrates were added to commercial sugar-reduced fruit spreads (raspberry-Aloe vera, strawberry-guava, and strawberry-lime), and tested for their antifungal activities. Selected strains of the species Absidia glauca, Penicillium brevicompactum, Saccharomyces cerevisiae and Zygosaccharomyces bailii, as well as xerophilic environmental isolates of the genera Penicillium and Eurotium were used for challenge testing. Initially, varying concentrations of synthetic antifungal agents, such as sodium benzoate, potassium sorbate and butyl 4-hydroxybenzoate were tested against these fungi on wort agar containing 31% fructose at different pH values. Subsequently, the experiments were conducted in fruit spreads containing different concentrations of cranberry and lingonberry concentrates. The results of this study demonstrate that these concentrates were able to inhibit growth of visible colonies of xerophilic and non-xerophilic fungi. Cranberry and lingonberry concentrates are interesting candidates for natural preservation against fungal growth in sugar reduced fruit spreads.