Sorghum, being gluten-free, is often recommended as a safe food for celiac patients as gluten is associated with celiac disease. However, gluten absence in cereals causes technological inadequacies. ...Sourdough fermentation using functional starter cultures could produce desirable properties in gluten-free cereals. Sorghum flour was subjected to sourdough fermentation using functional lactic acid bacteria and yeast as starter cultures and their effects on the rheology, texture and nutritional properties of the sourdoughs were investigated. Pediococcus pentosaceus LD7 fermented sourdough had the highest storage modulus (G′) (3.07Pa) and loss modulus (G″) (6.23Pa), while P. pentosaceus SA8 sourdough had the least G′ (0.88Pa) and G″ (2.87Pa). Scanning electron micrograph of the sorghum sourdough breads revealed an intact and less porous cell structure in the samples containing starters in comparison to the control sample. The sourdough bread produced with P. pentosaceus SA8 and S. cerevisiae YC1 had the highest total dietary fibre (17.2%) but least protein content (4.9%). The starters modified the structure and nutrients of the sourdough where P. pentosaceus LD7 exhibited the most significant effect on the rheological properties. The study showed that the use of the selected starter cultures is useful in improving the structure and nutrient of sorghum-based gluten-free breads.
•Sorghum sourdough was produced with functional lactic acid bacteria and yeast.•Pediococcus pentosaceus LD7 fermented sourdough had the highest storage modulus.•Starter cultures improved the cell structures and nutrients of the sourdough breads.
Thirty‐two lactic acid bacteria (LAB) isolates were obtained from fermenting cassava mash and wara (African soft cheese) and screened for their resistance to cadmium and lead toxicities at ...550–1050 mg l−1 and probiotic potentials. Four LAB strains that tolerated the heavy metals at 1050 mg l−1 were selected for antioxidative capacities, tolerance to acid, bile salts and simulated gastric and intestinal tract and safety status. The results revealed that Weissella cibaria WD2 and Lactobacillus plantarum CaD1 exhibited comparatively higher antioxidative capacities, survived in simulated gastric and intestinal transit, tolerated acid and bile salt and possessed safety status. The two strains were employed for the in vivo studies, which was monitored in male albino Wistar rats using skim milk as a carrier for the cultures over a period of 28 days. The rats given the cultures of W. cibaria WD2 and L. plantarum CaD1 in addition with the administration of heavy metals had improved renal and hepatic impairment, while damage was observed in rats fed with cadmium and lead only. Weissella cibaria WD2 and L. plantarum CaD1 demonstrated probiotic potentials and safety status. These strains can be used to effectively amend hepatic and renal histopathological alterations in rats caused by ingestion of cadmium and lead.
Significance and Impact of the Study
This present study highlights the presence of lactic acid bacteria (LAB) from traditional fermented foods that were cadmium and lead resistant and possessed probiotic potentials. Weissella cibaria WD2 and Lactobacillus plantarum CaD1 selected for the in vivo studies ameliorated the build‐up of cadmium and lead in the organs of the animals. This indicated that good cadmium and lead binding and probiotic lactic acid bacteria can be used to prevent exposure to these heavy metals.
Significance and Impact of the Study: This present study highlights the presence of lactic acid bacteria (LAB) from traditional fermented foods that were cadmium and lead resistant and possessed probiotic potentials. Weissella cibaria WD2 and Lactobacillus plantarum CaD1 selected for the in vivo studies ameliorated the build‐up of cadmium and lead in the organs of the animals. This indicated that good cadmium and lead binding and probiotic lactic acid bacteria can be used to prevent exposure to these heavy metals.
Vision is a vital attribute to foraging, navigation, mate selection and social signalling in animals, which often have a very different colour perception in comparison to humans. For understanding ...how animal colour perception works, vision models provide the smallest colour difference that animals of a given species are assumed to detect. To determine the just-noticeable-difference, or JND, vision models use Weber fractions that set discrimination thresholds of a stimulus compared to its background. However, although vision models are widely used, they rely on assumptions of Weber fractions since the exact fractions are unknown for most species. Here, we test; i) which Weber fractions in long-, middle- and shortwave (i.e. L, M, S) colour channels best describe the blue tit (Cyanistes caeruleus) colour discrimination, ii) how changes in hue of saturated colours and iii) chromatic background noise impair search behaviour in blue tits. We show that the behaviourally verified Weber fractions on achromatic backgrounds were L: 0.05, M: 0.03 and S: 0.03, indicating a high colour sensitivity. In contrast, on saturated chromatic backgrounds, the correct Weber fractions were considerably higher for L: 0.20, M: 0.17 and S: 0.15, indicating a less detailed colour perception. Chromatic complexity of backgrounds affected the longwave channel, while middle- and shortwave channels were mostly unaffected. We caution that using a vision model whereby colour discrimination is determined in achromatic viewing conditions, as they often are, can lead to misleading interpretations of biological interactions in natural – colourful – environments.
The diversity and technological properties of Pediococcus pentosaceus strains, isolated from some traditional fermented foods in Nigeria, were studied with the aim of selecting suitable strains as a ...starter and/or adjunct cultures. Eighteen lactic acid bacteria isolates from ogi, gari and fufu were presumptively identified as Pediococcus species using the conventional methods, these isolates were screened for technological and safety properties such as exopolysaccharide production, acidifying activity, antimicrobial activity, and biogenic amine production. The LAB isolates were further differentiated by using internal transcribed spacer-restriction fragment length polymorphism (ITS-RFLP), randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and pulsed-field gel electrophoresis (PFGE) molecular typing techniques. The Pediococcus sp. displayed antimicrobial activities against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecium. They all had high acidifying activities and were able to reduce the pH to lower than 5.20 after 24 h. Pediococcus pentosaceus OF31 showed interesting potential technological characteristics due to its antimicrobial activity and exopolysaccharide production. The combination of RAPD-PCR (using primers OPA20 and M13) and PFGE-SfiI genotypic fingerprinting technique allows successful intraspecific differentiation. The present study confirmed the presence of exopolysaccharide-producing strain of P. pentosaceus in indigenous fermented foods which could be used as autochthonous starter culture to impart more functional attributes to fermented foods.
•Pediococcus sp. of food origin were phenotypically and genotypically characterised.•P. pentosaceus strains isolated can be used as adjunct culture for controlled fermentation.•Combination of different molecular tools allowed strain differentiation.
Aim
To identify enterococci from the fermentation of milk for the production of nono, an African fermented dairy product, to determine the technological properties for suitability as starter cultures ...and safety as probiotics.
Methods and Results
Enterococcus faecium CM4 and Enterococcus faecium 2CM1 were isolated from raw cow's milk. The strains were phenotypically and genotypically identified. Technological properties, safety investigations, in vitro adherence properties and antimicrobial characteristics were carried out. Strong acidification and tolerance to bile salts were recorded. The strains were bile salts hydrolytic positive and no haemolysis. There was no resistance to clinically relevant antibiotics. The strains exhibited adherence to human collagen type IV, human fibrinogen and fibronectin. The bacteriocins were active against Bacillus cereus DSM 2301, Bacillus subtilis ATCC 6633, Micrococcus luteus and Listeria monocytogenes. Bacteriocins were stable at pH 4–9 and on treatment with lipase, catalase, α‐amylase and pepsin, while their activity was lost on treatment with other proteases. The bacteriocins produced were heat stable at 100°C for 10 min. The bacteriocin produced by the strains was identified as enterocin A.
Conclusions
The E. faecium strains in this study exhibited probiotic activity, and the safety investigations indicate their suitability as good candidates for a starter culture fermentation process.
Significance and Impact of the Study
The use of bacteriocin‐producing E. faecium strains as starter cultures in fermented foods is beneficial but, however, their safety investigations as probiotics must be greatly emphasized.
Sorghum, a gluten-free diet usually recommended for celiac patients, can be improved with functional indigenous starters. Sourdough breads were prepared from sorghum flour using selected lactic acid ...bacteria and yeast starter cultures. Sensorial attributes, antioxidant properties and in-vitro digestibility of the sourdoughs were studied. The sourdough bread produced with Pediococcus pentosaceus SA8 showed the highest overall acceptability (6.9). Furthermore, Weissella confusa SD8 sourdough had the highest total phenolic and total flavonoid contents (33.08 mg GAE/100 g and 13.79 mg/100 g, respectively), while the control had the least (27.69 mg GAE/100 g and 13.66 mg/100 g, respectively). Sourdough addition enhanced protein digestibility of the breads. The selected starter cultures improved the consumer acceptability, antioxidant properties and protein digestibility of sorghum flour in sourdough fermentation. Therefore, they exhibited great potentials as suitable for developing a safe and effective therapeutic alternative to gluten-containing foods for celiac patients.
•Sorghum sourdough bread was produced with selected lactic acid bacteria and yeast.•Pediococcus pentosaceus SA8 sourdough bread had highest overall acceptability.•Weissella confusa SD8 sourdough was the highest in total phenolic.•The starters improved the protein digestibility of the sourdough breads.•The sourdough breads could be a source of phytoceuticals for celiac patients.
Fluorescent nanoparticles as tools in ecology and physiology Färkkilä, Sanni M. A.; Kiers, E. Toby; Jaaniso, Raivo ...
Biological reviews of the Cambridge Philosophical Society,
October 2021, 2021-10-00, 20211001, Volume:
96, Issue:
5
Journal Article
Peer reviewed
Open access
ABSTRACT
Fluorescent nanoparticles (FNPs) have been widely used in chemistry and medicine for decades, but their employment in biology is relatively recent. Past reviews on FNPs have focused on ...chemical, physical or medical uses, making the extrapolation to biological applications difficult. In biology, FNPs have largely been used for biosensing and molecular tracking. However, concerns over toxicity in early types of FNPs, such as cadmium‐containing quantum dots (QDs), may have prevented wide adoption. Recent developments, especially in non‐Cd‐containing FNPs, have alleviated toxicity problems, facilitating the use of FNPs for addressing ecological, physiological and molecule‐level processes in biological research. Standardised protocols from synthesis to application and interdisciplinary approaches are critical for establishing FNPs in the biologists’ tool kit. Here, we present an introduction to FNPs, summarise their use in biological applications, and discuss technical issues such as data reliability and biocompatibility. We assess whether biological research can benefit from FNPs and suggest ways in which FNPs can be applied to answer questions in biology. We conclude that FNPs have a great potential for studying various biological processes, especially tracking, sensing and imaging in physiology and ecology.
The production, optimization, and characterization of exopolysaccharide (EPS) from Weissella confusa OF126 and the in-vitro probiotic potentials of this strain was investigated. The EPS produced on ...sucrose modified-MRS broth was characterized. The purified EPS had an average molecular weight of 1.1 × 106 Da. HPLC analysis revealed the presence of glucose monomers, indicating its homopolysaccharide nature. The structural characteristics of the EPS were investigated by FTIR, and NMR spectroscopy. FTIR spectroscopy revealed the presence of hydroxyl, carboxyl, N-acetyl and amine groups. NMR analysis confirmed that the EPS contained α-(1 → 6) linkage and α-(1 → 3) branched linkage. The EPS showed strong in-vitro antioxidant activity. Four significant factors were optimized using Central Composite Design (CCD) and Response Surface Methodology (RSM). The predicted optimum conditions for EPS production were cultivation time (48.50 h), sucrose concentration (24.00 g/L), pH (7.00) and yeast extract (2.50%).The EPS produced was predicted to be 3.10 g/L, while the experimental yield was 3.00 g/L. This strain was found to possess desirable probiotic attributes by its ability to survive at pH 2.0 and in the presence of bile salts (0.50% (w/v)) for 4 h. The results obtained from this study demonstrate W. confusa OF126 as a promising probiotic and the EPS produced can find useful applications in industries.
Mycotoxins contamination in some agricultural food commodities seriously impact human and animal health and reduce the commercial value of crops. Mycotoxins are toxic secondary metabolites produced ...by fungi that contaminate agricultural commodities pre- or postharvest. Africa is one of the continents where environmental, agricultural and storage conditions of food commodities are conducive of Aspergillus fungi infection and aflatoxin biosynthesis. This paper reviews the commodity-wise aetiology and contamination process of aflatoxins and evaluates the potential risk of exposure from common African foods. Possible ways of reducing risk for fungal infection and aflatoxin development that are relevant to the African context. The presented database would be useful as benchmark information for development and prioritization of future research. There is need for more investigations on food quality and safety by making available advanced advanced equipments and analytical methods as well as surveillance and awareness creation in the region.
Near-infrared spectroscopy (NIRS) uses the relative absorption of light at 850 and 760 nm to determine skeletal muscle oxygen saturation. Previous studies have used the ratio of both signals to ...report muscle oxygen saturation.
The purpose of this pilot study is to assess the different approaches used to represent muscle oxygen saturation and to evaluate the pulsations of oxygenated hemoglobin/myoglobin (O
heme) and deoxygenated hemoglobin/myoglobin (Heme) signals.
Twelve participants, aged 20-29 years, were tested on the forearm flexor muscles using continuous-wave NIRS at rest. Measurements were taken during 2-3 min rest, physiological calibration (5 min ischemia), and reperfusion. Ten participants were included in the study analysis.
There was a significant difference in pulse size between O
heme and Heme signals at the three locations (
< 0.05). Resting oxygen saturation was 58.8% + 9.2%, 69.6% + 3.9%, and 89.2% + 6.9% when calibrated using O
heme, the tissue oxygenation/saturation index (TSI), and Heme, respectively.
The difference in magnitude of O
heme and Heme pulses with each heartbeat might suggest different anatomical locations of these signals, for which calibrating with just one of the signals instead of the ratio of both is proposed. Calculations of physiological calibration must account for increased blood volume in the tissue because of the changes in blood volume, which appear to be primarily from the O
heme signal. Resting oxygen levels calibrated with Heme agree with theoretical oxygen saturation.
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