Characterization and Technological Properties of Lactic Acid Bacteria in the Production of “Sorghurt,” a Cereal-Based Product

A total of 57 predominant LAB strains isolated from cassava and maize grains fermentation processes for fufu and ogi were identified using phenotypic and genomic fingerprinting methods such as rep-PCR and ARDRA. They were divided into facultatively heterofermentative rods (26.3%), obligately heterofermentative rods (31.6%), and tetrad forming homofermentative cocci (42.1%). Selected strains were further identified by sequencing the 16S rDNA gene. Technological studies such as acidification, hydrogen peroxide production, starch hydrolysis, enzymatic activities, degradation of oligosaccharides, and in vitro adherence properties were carried out. Lactobacillus plantarum strains demonstrated better and rapid acid production capability, followed by the Pediococcus strains, while L. fermentum strains exhibited slower acid production. Hydrogen peroxide production was observed among the LAB groups. The test strains utilized the indigestible sugars raffinose and stachyose. Only L. pentosus demonstrated high amylase activity comparable to that of L. amylovorus DSM 20531. Lactobacillus plantarum and L. fermentum strains showed high β-glucosidase activity. Six strains were selected as starter cultures. The strains were tolerant to acidic pH levels and bile salt. The yoghurt-like “sorghurt” produced using the selected starter cultures had a final pH of less than pH 4.0, and a viable count of less than 5.5 Log₁₀cfu/mL at the end of a 24 h fermentation period. The samples were generally acceptable to the taste panelists. The starter organisms demonstrated varying degree of adherence to HT29 MTX cell line. Therefore, employing functionally defined LAB strains may be one practical approach for incorporating health-promoting features into appropriate food products suitable for targeted population.     

Molecular Characterization of Lactic Acid Bacteria in Levačka Sausage

Levačka sausage is traditionally fermented dry sausage which is produced in central Serbia. It is made of beef and pork with the addition of solid fat and natural spices. The whole manufacturing process lasted for 21 days. The goal of this study was to create a collection of lactic acid bacteria isolated during the fermentation and identify them using molecular methods. A total of 50 isolates from different stages of fermentation were identified by molecular methods. Pediococcus pentosaceus, Ln. mesenteroides were predominant microorganisms in levačka sausage. Lb. curvatus, Lb. sakei and Lb. carnosum were also identified.     

Capillary Isoelectric Focusing—Useful Tool for Detection and Quantification of Lactic Acid Bacteria in Milk

The lactic acid bacteria (LAB), including lactobacilli and enterococci, represent an important part of normal microflora in humans. Simultaneously, they are frequently used as probiotics and in food industry for production of fermented milk products. The rapid and sensitive detection of these microorganisms is crucial for the quality control. In this study, the capillary isoelectric focusing (CIEF) was successfully used for the separation and characterization of probiotic LAB, L. paracasei sp. paracasei; L. acidifarinae; L. fermentum; L. gasseri; L. helveticus; L. plantarum; L. delbrueckii; L. salivarius; E. durans; E. faecalis; and E. faecium, according to their isoelectric points (pI). All pIs of lactobacilli and enterococci were found in the acidic part of the pH range. Subsequently, the milk samples spiked with L. rhamnosus, and E. faecium were analyzed by CIEF. The optimal adjustment of the separation conditions allowed detection and quantification of the bacteria in the sample with sufficient sensitivity. Therefore, CIEF is an efficient approach to rapid detection and separation of LAB even directly in milk products in future.     

Temperature-Dependent Dielectric Properties of Raw Cow’s and Goat’s Milk from 10 to 4,500 MHz Relevant to Radio-frequency and Microwave Pasteurization Process

To offer useful information for milk pasteurization with radio-frequency or microwave heating, the dielectric properties (dielectric constant and dielectric loss factor) of raw cow’s milk and goat’s milk were determined over the frequency range of 10–4,500 MHz and temperature range of 25–75 °C by a vector network analyzer and an open-ended coaxial-line probe. The mathematical models describing the relationship between permittivities and temperature were built, and the power penetration depth was investigated. The results showed that both for cow’s milk and goat’s milk, the dielectric constants decreased with an increase of frequency, and the dielectric loss factor decreased with increasing frequency below 1,000 MHz and increased after that. The dielectric constants decreased with increasing temperature at a given frequency. For raw cow’s milk, the dielectric loss factor almost increased with temperature below about 800 MHz, and decreased with temperature above that. For raw goat’s milk, the loss factor decreased with temperature in whole investigated frequency range. Quadratic equations could be used to describe the relationship between permittivities and temperature at interested frequencies with coefficient of determination higher than 0.96. The penetration depth decreased with increasing frequency. Contrasted to frequency, temperature had less effect on penetration depth. Microwave heating at 915 MHz has great potential for raw cow’s milk pasteurization, while radio-frequency heating at 27.12 and 40.68 MHz and microwave heating at 915 MHz can be used for goat’s milk pasteurization.     

Microbiological Profile of Goat Meat Inoculated with Lactic Acid Bacteria Cultures and Stored at 30��C for 7?days

The ability of lactic acid bacteria (LAB) cultures to preserve goat meat at 30°C was evaluated in the present study. Strains of Pediococcus pentosaceus GOAT 01 and Lactobacillus plantarum GOAT 012, individually and in combination, were applied as starters on sliced meat samples at 6 log cfu/g and stored for 7 days at 30°C to simulate ambient temperature in Nigeria. They were evaluated for microbiological profile during storage. Reduction in bacterial counts was recorded for enterobacteriaceae, Staphylococcus, yeasts and moulds in starter culture inoculated samples (SCIS), whereas an increase occurred in uninoculated control samples (UCS). In challenge experimental trials, two different sets of meat were inoculated individually with 6 log cfu/g each of pathogenic organisms, Listeria monocytogenes and Salmonella Typhimurium. The inoculated pathogens were monitored during storage to assess the influence of starter cultures on them. Approximately 1 log reduction was recorded in the viable count of L. monocytogenes on day 1, while counts were below detection limit (<2 log) on day 2 in meat samples inoculated with P. pentosaceus alone and in combination with L. plantarum. Counts of Salmonella Typhimurium showed about 2 log reduction in SCIS, inoculated with P. pentosaceus alone and in combination with L. plantarum, on day 2 while an increase by 4 logs was observed in UCS. Our findings suggest that the protective effect of the LAB strains could be exploited in shelf life extension and control of foodborne pathogens in goat meat. If the starter strains could be improved upon, their potential as biopreservatives may be engaged in the preservation of the meat in Nigeria, where storage systems have been very inadequate.     

Occurrence and Antibiotic Susceptibility Profile of Streptococcus spp. Isolated from Ewe＇s Milk

The purpose of this study was to determine the occurrence and antimicrobial resistance of Streptococcus spp. isolated from fresh ewe＇s milk and consequently to draw conclusions concerning the health condition of the animal flocks and the current trends of antibiotic use in small ruminants. A total of 77 mountainous sheepfolds were investigated representing 10% of all transhumant sheep and goats flocks in the area. Duplicate milk samples were collected from January to February transferred to the laboratory and analyzed for the presence of Streptococcus spp. by using the serial dilution method and plating on the surface of Slanetz and Bartley agar. The isolates were tested against nine antimicrobial agents with the Kirby-Bauer disk diffusion method. The results showed that Streptococcus spp. occurred in 84.4% of the samples and in counts ranged between 1.8 log CFU/mL and 4.6 log CFU/mL. Concerning susceptibility, only 1.3% of the isolates were resistant to all antimicrobials while 27.3% were fully susceptible. Resistance to cefepime was the most common （93.1%） observation followed by resistance to ampicillin （82.1%）, ciprofloxacine （58.3%） and meropenem （51.9%）. The isolates were vancomycin susceptible at a rate of 83.6%. Multidrug resistance to at least three antibiotics was observed to be 22.1% of Streptococcus spp.. Given the prevalence of Streptococcus spp. and the elevated resistance of isolates to various antibiotics it is concluded that further examinations and even interventions are required in order to pertain the appropriate animal health and milk quality.     

Continuous Production of Lactic Acid from Whey Perméate by Free and Calcium Alginate Entrapped Lactobacillus helveticus

Lactobacillus helveticus strain milano was used for the continuous fermentation of lactic acid in cheese whey-yeast extract permeate medium. The best productivity of lactic acid was with the free cell system, which was 9.7 g/L per h at a dilution rate of .352 h⁻¹. Under such conditions, lactose conversion was 87.5%, based on the lactose concentration of 37.4 g/L in feed. Under high dilution rates, the cells were elongated to several times their normal size, resulting in wall growth. The cell growth on the fermentor wall caused system instability; however, it prevented cell wash-out under high dilution rates. The packed bed column system using Ca alginate entrapped cells is not suitable for practical application. Nonuniform pH control, plugging of the column by leaked cells, and decalcification of Ca alginate beads were major drawbacks of the packed bed system.     

Screening and Characterization of Lactobacillus sp. from the Water of Cassava’s Fermentation for Selection as Probiotics

The present study aimed to evaluate selected probiotic properties of Lactobacilli isolated from the water of submerged cassava fermentation. Following Lactobacilli isolation, isolates were screened for their antimicrobial activity. Acid and bile tolerances, bile salt hydrolase (Bsh) activity spectrum were assessed. Among the 113 isolates obtained, 16 showed a broad antimicrobial activity spectrum against the indicator microorganisms. From these 16, 12 were found acid and bile resistant. They hydrolyzed glycoconjugated or tauroconjugated bile salts. From the four bile Bsh genes screened, only Bsh-Lp1 was found in five isolates. They identified as Lactobacillus paraplantarum, Lactobacillus paracasei, Lactobacillus brevis, and Lactobacillus plantarum. Based on the principal component analysis, L. paracasei 62L, L. plantarum 85L and 86L were selected as the most promising strains. These results suggest that water from submerged cassava fermentation can be a source of Lactobacilli with high probiotic potential.     

Physico-Chemical Characterization of Oils Extracted from Noni,Spinach, Lady’s Finger,Bitter Gourd and Mustard Seeds,and Copra

The physico-chemical properties of solvent-extracted oil from the seeds of noni (Morinda citrifolia L.), spinach (Spinacia oleracea L.), lady’s finger (Abelmoschus esculentus (L.) Moench), bitter gourd (Momordica charantia L.), mustard (Brassica nigra (L.) Koch), and the dried kernel (copra) of coconut (Cocos nucifera L.) were characterized. Among these sources, spinach seed had the lowest oil content (4.5 ± 0.4%) while coconut kernel had the highest oil content (63.1 ± 2.8%). Palmitic, oleic, and linoleic acids were the major fatty acids for spinach, lady’s finger and noni seed oils, while erucic, eleostearic, and lauric acids were the major fatty acids for mustard seed oil, bitter gourd seed oil, and coconut kernel oil, respectively. All of the oils possessed at least three major peaks in their triacylglycerol profiles except for bitter gourd seed oil which had only one major peak (1-stearoyl, 2,3-dieleostearoyl). The last endothermic peaks were –12.4, –6.0, 6.8, 57.7, 2.7, and 24.3ºC for noni, spinach, lady’s finger, bitter gourd and mustard seed oils, and coconut oil, respectively. Initially, the solid fat content of bitter gourd seed oil decreased gradually, but became rapidly after 50 until 60ºC. Coconut oil had its solid fat content reduced rapidly around 14 to 28ºC.     

Recovery of protein hydrolysates from brewer’s spent grain using enzyme and ultrasonication

The aim of this study was to develop a green ultrasound-assisted enzymatic process to separate protein from brewer’s spent grain (BSG) to produce protein hydrolysates and determine the physicochemical properties of produced protein hydrolysates. When the enzyme (Alcalase) loading increased from 1 to 20 μL g⁻¹ BSG, the protein separation efficiency increased from 34.0% to 61.6%. The application of ultrasound pretreatment further increased protein separation efficiency to 69.8%. More promisingly, the ultrasound pretreatment was able to reduce enzyme loading by 73% and decrease enzyme incubation time by 56%. The produced protein hydrolysates had molecular weights lower than 15 kDa and high protein solubilities at the pH of 1.0–11.0. The ultrasound pretreatment improved the protein solubility to above 90%. Glutamic acid and proline were the most abundant amino acids in produced protein hydrolysates. This study demonstrated that enzymatic hydrolysis along with ultrasound pretreatment is an effective way to separate protein from BSG.     

Effect of Different Cooking Conditions on the Pasting Properties of Flours of Glutinous Rice Varieties from Lao People’s Democratic Republic

The effect of different rehydration temperatures (30, 40, and 50°C) and cooking times (2.7, 4.7, 6.7, 8.7, and 10.7 min) at 95°C on the pasting properties of three glutinous varieties (Thadokkham-11, Thadokkham-8, and Hom Mali Niaw) from Lao People’s Democratic Republic was investigated using rapid visco analyzer. Non-glutinous varieties (IR64 and Doongara) were also analyzed to compare glutinous (amylose <4.5%) and non-glutinous (amylose >15%) varieties. All rice flours took up water at significantly (p < 0.05) higher rates in the case of increased temperature and soaking time, resulting in a decrease in the onset temperature for pasting. Among the glutinous rices, Thadokkham-8 showed a significant (p < 0.05) decrease in peak viscosity in response to increased rehydration time and temperature. For this variety maximum viscosity (2403.3 mPas) was observed at 1 min of rehydration at 30°C and minimum viscosity (1852.0 mPas) at 15 min of rehydration at 50°C. The viscosity values of Thadokkham-11 and Hom Mali Niaw varieties increased to their highest values (1608.7 and 1477.7 mPa.s, respectively) with an increase in temperature to 40°C for 1 min. In general, the glutinous rices produced weaker gel than non-glutinous rices. Extended holding at cooking temperature (95°C) had a more significant (p < 0.05) effect on the glutinous varieties Thadokkham-8 and Thadokkham-11 than on the non-glutinous varieties (IR64 and Doongara) used in this study.     

Technological Performance of the Enterocin A Producer <Emphasis Type="Italic">Enterococcus faecium</Emphasis> MMRA as a Protective Adjunct Culture to Enhance Hygienic and Sensory Attributes of Traditional Fermented Milk ‘Rayeb’

Enterococcus faecium MMRA is an enterocin A producer isolated from ‘Rayeb’, a Tunisian fermented milk drink. In this work, safety aspects and its behaviour in raw milk were investigated to assess its suitability as a protective adjunct culture. E. faecium MMRA showed interesting features such as the absence of several virulence traits, susceptibility to vancomycin and other clinically relevant antibiotics, and lack of haemolytic activity. To evaluate its performance as an adjunct culture for Rayeb, changes in the overall composition of control (non-inoculated) and experimental Rayeb (inoculated with 1%, v/v, E. faecium MMRA) were determined throughout duplicate fermentations of raw milk using microbiological, chemical, HPLC and headspace GC-MS analyses. E. faecium MMRA could multiply in raw milk and produced enterocin A. Interestingly, a higher content of volatile compounds including ethanol, diacetyl and 2-propanol was observed in the presence of this bacteriocin producer. Furthermore, this strain was capable of inhibiting the growth of Listeria monocytogenes CECT 4032 in pasteurised milk, although total killing was not achieved. Further experiments confirmed the development of resistant variants to enterocin A. On similar challenge assays, L. monocytogenes CECT 5672 growth was halted by the presence of the enterocin producer, but viability was only slightly reduced during cold storage. According to our results, E. faecium MMRA meets the criteria for an autochthonous protective adjunct culture to enhance both the hygienic and the sensory attributes of Rayeb.     

Isolation of xanthones from adventitious roots of St. John’s Wort (Hypericum perforatum L.) and their antioxidant and cytotoxic activities

In this phytochemical study, 5 xanthones, 1,3,5,6-tetrahydroxyxanthone [1], 1,5,6-trihydroxy-3-methoxyxanthone [2], ferrxanthone [3], brasilixanthone B [4], and neolancerin [5] were isolated from adventitious roots of St. John’s wort (Hypericum perforatum L.). Compound 1–5 were evaluated for antioxidant activities using the intracellular reactive oxygen species (ROS) radical scavenging 2′,7′-dichlorfluorescein-diacetate (DCFDA) assay and for cytotoxic activity against the HL-60 human promyelocytic leukemia cells. Among them, compound 1–4 exhibited scavenging activity with inhibition values of 27.4–33.2% at 10 μM; compound 1, 2, and 4 reduced the viability of HL-60 cells significantly, with IC₅₀ values of 31.5, 28.9, and 27.7 μM, respectively.