Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the via... more Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the viable numbers of Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, and Esherichia coli below the detection limit after incubation for 5 min when combined with lactoperoxidase, glucose oxidase, and glucose. Some extracts showed higher bactericidal activity and a higher OI À concentration in the assay mixture after ultrafiltration.
The high organic content of abattoir-associated process water provides an alternative for low-cos... more The high organic content of abattoir-associated process water provides an alternative for low-cost and non-invasive sample collection. This study investigated the association of microbial diversity from an abattoir processing environment with that of chicken meat. Water samples from scalders, defeathering, evisceration, carcass-washer, chillers, and post-chill carcass rinsate were collected from a large-scale abattoir in Australia. DNA was extracted using the Wizard® Genomic DNA Purification Kit, and the 16S rRNA v3-v4 gene region was sequenced using Illumina MiSeq. The results revealed that the Firmicutes decreased from scalding to evisceration (72.55%) and increased with chilling (23.47%), with the Proteobacteria and Bacteroidota changing inversely. A diverse bacterial community with 24 phyla and 392 genera was recovered from the post-chill chicken, with Anoxybacillus (71.84%), Megamonas (4.18%), Gallibacterium (2.14%), Unclassified Lachnospiraceae (1.87%), and Lactobacillus (1.80...
This study aims to characterise Bacillus subtilis complex group from raw, pasteurised and package... more This study aims to characterise Bacillus subtilis complex group from raw, pasteurised and packaged extended shelf-life (ESL) milk samples, to determine their biofilm potential and source-track the microbial contaminants in order to control their presence during processing. The isolates were characterised using multi-locus sequence typing (MLST) with seven housekeeping genes. The primers used were designed from the coding regions with the highest number of polymorphic sites. The heat resistance profile indicated all 12 isolates are psychrotolerant as well as thermophilic with temperature ranges of 6°C to 55°C (B43, B44, B52, B54, B55, B56, B57), 6°C to 60°C (B46, B47, B48) and 15°C to 60°C (B49, B50). A General Linear Model (GLM) two-way repeated measure ANOVA of the biofilm-forming potential of the isolates shows that there is a statistically significant difference across the time (6, 12, 18 and 24 hrs) of incubation (P< 0.05). All the isolates formed moderate to strong biofilms except 2 with B44 having the most robust biofilm formation (3.14 ±0.60). The scanning electron and confocal microscopy images reveal the strain-specificity of the biofilm structure. The MLST analysis identified all isolates to either belong to B. subtilis or B. velezensis. All the isolates are novel sequence types (STs) when compared to the PubMLST Page 1 of 32 ScholarOne support: (434) 964 4100 Journal of Dairy Science database but showed relatedness to those isolates in the raw milk that was processed. The closest STs are 96 for B. velezensis and 128 for B. subtilis mostly isolated from the soil. The study presents the significance of biofilms of thermophilic B. subtilis B. velezensis and possible perpetuation in the dairy processing plant. The information provided is a call for an innovative food contact surface or any other intervention that can minimise or prevent microbial adhesion in the processing plant which in turn impact negatively in ESL milk.
The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and g... more The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and growth of Bacillus cereus spores isolated from raw milk and biofilms in filler nozzles from extended shelf life (ESL) milk processing lines. Simulated CIP treatment structurally affected >98% of B. cereus spores, while 0.1% remained intact. Following simulated CIP treatment, B. cereus spores were able to attach to stainless steel coupons and form biofilms. B. cereus spores were capable of germination and growth under refrigerated conditions for more than 28 days. Contamination with B. cereus spores may lead to a reduced shelf life and potentially be a safety risk in ESL milk with a prolonged shelf life.
Bacterial spores are of concern in food processing due to their ubiquity and resistance. This stu... more Bacterial spores are of concern in food processing due to their ubiquity and resistance. This study seeks to determine the effect of ultraviolet C (UV-C) in the inactivation of spores of Bacillus subtilis and Bacillus velezensis that can result in enzymatic spoilage in foods using PBS as the suspension medium. Purified spore samples were treated under 1 pass in a UV-C reactor using 10 mL of spore inoculum with one dose of the radiation (410 mJ/cm2) for 10secs at room temperature. Aliquots of the treated samples were plated on tryptone soy agar supplemented with 0.6% glucose and the colonies counted. Flow cytometry analysis was done using 500 μL of both treated and control samples with a cell concentration of a ≥106 CFU/ml with propidium iodide (15 μM) and SYTO 9 (500 nM) used as live/dead stains. Samples were processed for microscopy (SEM and Raman-AFM Imaging). The maximum lethality is 2.5 for B. velezensis and the minimum is 0.1 for B. subtilis. Microscopic imaging of treated spor...
International Journal of Food Science & Technology, 2019
Because gluten-free type brewing with unmalted sorghum does not provide adequate nitrogen for com... more Because gluten-free type brewing with unmalted sorghum does not provide adequate nitrogen for complete fermentation, wort supplementation with ammonia (as diammonium phosphate, DAP) or lysine on yeast performance was investigated. By Phenotype Microarray, under aerobic conditions, greater yeast growth was indicated with DAP than lysine both as a single source and combined with sorghum wort amino acids. With sorghum fermentation, both DAP and lysine improved maltose and maltotriose uptake. However, DAP supplementation also maintained yeast numbers (24.0-21.3 9 10 6 cells mL À1), whereas there was a decline with lysine supplementation. Lysine supplementation also resulted in adverse effects on yeast cell morphology. Neither DAP nor lysine supplementation resulted in evident genetic change to the yeast, but the change in substrate from barley malt wort to unmalted sorghum wort slightly altered the yeast genetically. Therefore, ammonia as DAP has potential as a nitrogen supplement for improving yeast fermentation performance in sorghum gluten-free brewing.
Characterisation of spore formers associated with extended shelf life milk was performed by analy... more Characterisation of spore formers associated with extended shelf life milk was performed by analysing the bacteriological quality of milk samples collected at various processing stages and during storage. Isolates were identified with MALDI-TOF-MS. Milk had spore counts <2 log 10 cfu/mL and 4 log 10 cfu/mL during processing and storage, respectively. Bacillus pumilus dominated the bacterial population. Bacterial species were inoculated into sterile milk for a shelf life study, and the population change was observed over 42 days at 7°C. Although the extended shelf life milk process was effective in reducing bacterial counts and species diversity, the presence of Bacillus cereus shows a potential safety problem in extended shelf life milk.
Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (car... more Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB 1 and FB 2) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB 1 most effectively while P. pentosaceus D39 bound the least level of FB 1. The highest levels of FB 2 were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB 1 and FB 2 , respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.
Critical Reviews in Food Science and Nutrition, 2019
Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iod... more Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iodine, and vitamin A since the beginning of the 21st century. Prioritizing the vitamin A deficiency (VAD) disorders, many countries are looking for viable alternative strategies such as biofortification. One of the leading causes of VAD is the poor bioconversion of b-carotene into retinoids. This review is focused on the opportunities of bacterial biosynthesis of retinoids, in particular, through the gut microbiota. The proposed hypothesis starts with the premise that an animal can able to store and timely convert carotenoids into retinoids in the liver and intestinal tissues. This theory is experimental with many scientific insights. The syntrophic metabolism, potential crosstalk of bile acids, lipocalins and lipopolysaccharides of gut microbiota are reported to contribute significantly to the retinoid biosynthesis. The gut bacteria respond to these kinds of factors by genetic restructuring driven mainly by events like horizontal gene transfer. A phylogenetic analysis of b-carotene 15, 15 0-mono (di) oxygenase enzymes among a selected group of prokaryotes and eukaryotes was carried out to validate the hypotheses. Shedding light on the probiotic strategies through nongenetically modified organism such as gut bacteria capable of synthesizing vitamin A would address the VAD disorders.
Steeping of cassava root pieces in 0.75% NaOH in combination with wet milling was investigated to... more Steeping of cassava root pieces in 0.75% NaOH in combination with wet milling was investigated to determine whether and how dilute NaOH modifies cassava cell walls. Gas chromatography data of cell wall constituent sugar composition and Fourier transform infrared (FTIR) data showed that NaOH steeping reduced the level of pectin in cassava cell walls. FTIR and wide-angle X-ray scattering spectroscopy also indicated that NaOH steeping combined with fine milling slightly reduced cellulose crystallinity. Scanning electron microscopy showed that NaOH steeping produced micropores in the cell walls and light microscopy revealed that NaOH steeping increased disaggregation of parenchyma cells. Steeping of ground cassava in NaOH resulted in a 12% decrease in large residue particles and approx. 4% greater starch yield with wet milling. Therefore dilute NaOH steeping can improve the effectiveness of wet milling in disintegrating cell walls through solubilisation of pectin, thereby reduced cell w...
The natural antimicrobial system present in milk, the lactoperoxidase (LP) system, has been used ... more The natural antimicrobial system present in milk, the lactoperoxidase (LP) system, has been used to preserve raw milk quality in areas where it is not possible to use mechanical refrigeration for technical and/or economic reasons. Although the most widely recommended industrial application of the LP system in food production is in the dairy industry for the preservation of raw milk during storage and/or transportation to processing plants, other novel applications of the LP system are being explored. This review paper addresses the use of the LP system in the dairy industry, new research findings and developments made so far and the potential applications of the LP system in other food systems and commercial products. The paper also highlights the research gap and possible future research directions that deserve attention.
Journal of the science of food and agriculture, 2015
Sorghum types suitable for brewing and bioethanol production are required. The effect of sorghum ... more Sorghum types suitable for brewing and bioethanol production are required. The effect of sorghum type (white non-tannin versus white type II tannin) on free amino nitrogen (FAN) production from sorghum grain and malt using exogenous protease enzymes was investigated over extended incubation at moderate temperature (45 °C). With grain in the absence of exogenous proteases, white non-tannin sorghum produced substantially higher levels of FAN than white type II tannin sorghum, due to the tannins in the latter. Incubating sorghum grain with neutral proteinase and amino-peptidase in combination improved FAN production. The two sorghum types produced similar FAN levels when malted and incubated in the absence of the exogenous proteases. When both sorghums were malted and incubated with neutral proteinase alone substantially more FAN yield (124-126 mg 100 g(-1)) occurred than with grains (61-84 mg 100 g(-1)). The combination of amino-peptidase and proteinase did not improve FAN further. Ne...
This study was conducted to determine the potential of lactoperoxidase (LP) for the diagnosis of ... more This study was conducted to determine the potential of lactoperoxidase (LP) for the diagnosis of subclinical mastitis in goats. The activities of LP and somatic cell counts (SCC) were determined in the milk of clinically healthy Saanen and South African Indigenous goats and the correlation between LP activity and SCC was measured. An increase in LP activity was observed with increasing number of somatic cells in the milk of the two goat breeds. A significantly (p < 0.01) positive correlation was observed between LP activity and SCC in the Indigenous (r = 0.91) and Saanen (r = 0.95) goat milk samples. The mean SCCs in Indigenous and Saanen goat milk samples were 2.5 × 10 4 and 2.0 × 10 6 cells/ml, respectively. The LP activity of Saanen goat milk ranged from 0.49 to 1.07 units/ml with a mean value of 0.80 units/ml. In the Indigenous goat milk, the LP activity ranged from 0.03 to 0.38 units/ml with a mean value of 0.26 units/ml. The positive correlation observed between SCC and LP activity suggests that LP may be used to detect subclinical mastitis in dairy goats.
Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the via... more Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the viable numbers of Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, and Esherichia coli below the detection limit after incubation for 5 min when combined with lactoperoxidase, glucose oxidase, and glucose. Some extracts showed higher bactericidal activity and a higher OI À concentration in the assay mixture after ultrafiltration.
The high organic content of abattoir-associated process water provides an alternative for low-cos... more The high organic content of abattoir-associated process water provides an alternative for low-cost and non-invasive sample collection. This study investigated the association of microbial diversity from an abattoir processing environment with that of chicken meat. Water samples from scalders, defeathering, evisceration, carcass-washer, chillers, and post-chill carcass rinsate were collected from a large-scale abattoir in Australia. DNA was extracted using the Wizard® Genomic DNA Purification Kit, and the 16S rRNA v3-v4 gene region was sequenced using Illumina MiSeq. The results revealed that the Firmicutes decreased from scalding to evisceration (72.55%) and increased with chilling (23.47%), with the Proteobacteria and Bacteroidota changing inversely. A diverse bacterial community with 24 phyla and 392 genera was recovered from the post-chill chicken, with Anoxybacillus (71.84%), Megamonas (4.18%), Gallibacterium (2.14%), Unclassified Lachnospiraceae (1.87%), and Lactobacillus (1.80...
This study aims to characterise Bacillus subtilis complex group from raw, pasteurised and package... more This study aims to characterise Bacillus subtilis complex group from raw, pasteurised and packaged extended shelf-life (ESL) milk samples, to determine their biofilm potential and source-track the microbial contaminants in order to control their presence during processing. The isolates were characterised using multi-locus sequence typing (MLST) with seven housekeeping genes. The primers used were designed from the coding regions with the highest number of polymorphic sites. The heat resistance profile indicated all 12 isolates are psychrotolerant as well as thermophilic with temperature ranges of 6°C to 55°C (B43, B44, B52, B54, B55, B56, B57), 6°C to 60°C (B46, B47, B48) and 15°C to 60°C (B49, B50). A General Linear Model (GLM) two-way repeated measure ANOVA of the biofilm-forming potential of the isolates shows that there is a statistically significant difference across the time (6, 12, 18 and 24 hrs) of incubation (P< 0.05). All the isolates formed moderate to strong biofilms except 2 with B44 having the most robust biofilm formation (3.14 ±0.60). The scanning electron and confocal microscopy images reveal the strain-specificity of the biofilm structure. The MLST analysis identified all isolates to either belong to B. subtilis or B. velezensis. All the isolates are novel sequence types (STs) when compared to the PubMLST Page 1 of 32 ScholarOne support: (434) 964 4100 Journal of Dairy Science database but showed relatedness to those isolates in the raw milk that was processed. The closest STs are 96 for B. velezensis and 128 for B. subtilis mostly isolated from the soil. The study presents the significance of biofilms of thermophilic B. subtilis B. velezensis and possible perpetuation in the dairy processing plant. The information provided is a call for an innovative food contact surface or any other intervention that can minimise or prevent microbial adhesion in the processing plant which in turn impact negatively in ESL milk.
The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and g... more The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and growth of Bacillus cereus spores isolated from raw milk and biofilms in filler nozzles from extended shelf life (ESL) milk processing lines. Simulated CIP treatment structurally affected >98% of B. cereus spores, while 0.1% remained intact. Following simulated CIP treatment, B. cereus spores were able to attach to stainless steel coupons and form biofilms. B. cereus spores were capable of germination and growth under refrigerated conditions for more than 28 days. Contamination with B. cereus spores may lead to a reduced shelf life and potentially be a safety risk in ESL milk with a prolonged shelf life.
Bacterial spores are of concern in food processing due to their ubiquity and resistance. This stu... more Bacterial spores are of concern in food processing due to their ubiquity and resistance. This study seeks to determine the effect of ultraviolet C (UV-C) in the inactivation of spores of Bacillus subtilis and Bacillus velezensis that can result in enzymatic spoilage in foods using PBS as the suspension medium. Purified spore samples were treated under 1 pass in a UV-C reactor using 10 mL of spore inoculum with one dose of the radiation (410 mJ/cm2) for 10secs at room temperature. Aliquots of the treated samples were plated on tryptone soy agar supplemented with 0.6% glucose and the colonies counted. Flow cytometry analysis was done using 500 μL of both treated and control samples with a cell concentration of a ≥106 CFU/ml with propidium iodide (15 μM) and SYTO 9 (500 nM) used as live/dead stains. Samples were processed for microscopy (SEM and Raman-AFM Imaging). The maximum lethality is 2.5 for B. velezensis and the minimum is 0.1 for B. subtilis. Microscopic imaging of treated spor...
International Journal of Food Science & Technology, 2019
Because gluten-free type brewing with unmalted sorghum does not provide adequate nitrogen for com... more Because gluten-free type brewing with unmalted sorghum does not provide adequate nitrogen for complete fermentation, wort supplementation with ammonia (as diammonium phosphate, DAP) or lysine on yeast performance was investigated. By Phenotype Microarray, under aerobic conditions, greater yeast growth was indicated with DAP than lysine both as a single source and combined with sorghum wort amino acids. With sorghum fermentation, both DAP and lysine improved maltose and maltotriose uptake. However, DAP supplementation also maintained yeast numbers (24.0-21.3 9 10 6 cells mL À1), whereas there was a decline with lysine supplementation. Lysine supplementation also resulted in adverse effects on yeast cell morphology. Neither DAP nor lysine supplementation resulted in evident genetic change to the yeast, but the change in substrate from barley malt wort to unmalted sorghum wort slightly altered the yeast genetically. Therefore, ammonia as DAP has potential as a nitrogen supplement for improving yeast fermentation performance in sorghum gluten-free brewing.
Characterisation of spore formers associated with extended shelf life milk was performed by analy... more Characterisation of spore formers associated with extended shelf life milk was performed by analysing the bacteriological quality of milk samples collected at various processing stages and during storage. Isolates were identified with MALDI-TOF-MS. Milk had spore counts <2 log 10 cfu/mL and 4 log 10 cfu/mL during processing and storage, respectively. Bacillus pumilus dominated the bacterial population. Bacterial species were inoculated into sterile milk for a shelf life study, and the population change was observed over 42 days at 7°C. Although the extended shelf life milk process was effective in reducing bacterial counts and species diversity, the presence of Bacillus cereus shows a potential safety problem in extended shelf life milk.
Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (car... more Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB 1 and FB 2) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB 1 most effectively while P. pentosaceus D39 bound the least level of FB 1. The highest levels of FB 2 were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB 1 and FB 2 , respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.
Critical Reviews in Food Science and Nutrition, 2019
Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iod... more Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iodine, and vitamin A since the beginning of the 21st century. Prioritizing the vitamin A deficiency (VAD) disorders, many countries are looking for viable alternative strategies such as biofortification. One of the leading causes of VAD is the poor bioconversion of b-carotene into retinoids. This review is focused on the opportunities of bacterial biosynthesis of retinoids, in particular, through the gut microbiota. The proposed hypothesis starts with the premise that an animal can able to store and timely convert carotenoids into retinoids in the liver and intestinal tissues. This theory is experimental with many scientific insights. The syntrophic metabolism, potential crosstalk of bile acids, lipocalins and lipopolysaccharides of gut microbiota are reported to contribute significantly to the retinoid biosynthesis. The gut bacteria respond to these kinds of factors by genetic restructuring driven mainly by events like horizontal gene transfer. A phylogenetic analysis of b-carotene 15, 15 0-mono (di) oxygenase enzymes among a selected group of prokaryotes and eukaryotes was carried out to validate the hypotheses. Shedding light on the probiotic strategies through nongenetically modified organism such as gut bacteria capable of synthesizing vitamin A would address the VAD disorders.
Steeping of cassava root pieces in 0.75% NaOH in combination with wet milling was investigated to... more Steeping of cassava root pieces in 0.75% NaOH in combination with wet milling was investigated to determine whether and how dilute NaOH modifies cassava cell walls. Gas chromatography data of cell wall constituent sugar composition and Fourier transform infrared (FTIR) data showed that NaOH steeping reduced the level of pectin in cassava cell walls. FTIR and wide-angle X-ray scattering spectroscopy also indicated that NaOH steeping combined with fine milling slightly reduced cellulose crystallinity. Scanning electron microscopy showed that NaOH steeping produced micropores in the cell walls and light microscopy revealed that NaOH steeping increased disaggregation of parenchyma cells. Steeping of ground cassava in NaOH resulted in a 12% decrease in large residue particles and approx. 4% greater starch yield with wet milling. Therefore dilute NaOH steeping can improve the effectiveness of wet milling in disintegrating cell walls through solubilisation of pectin, thereby reduced cell w...
The natural antimicrobial system present in milk, the lactoperoxidase (LP) system, has been used ... more The natural antimicrobial system present in milk, the lactoperoxidase (LP) system, has been used to preserve raw milk quality in areas where it is not possible to use mechanical refrigeration for technical and/or economic reasons. Although the most widely recommended industrial application of the LP system in food production is in the dairy industry for the preservation of raw milk during storage and/or transportation to processing plants, other novel applications of the LP system are being explored. This review paper addresses the use of the LP system in the dairy industry, new research findings and developments made so far and the potential applications of the LP system in other food systems and commercial products. The paper also highlights the research gap and possible future research directions that deserve attention.
Journal of the science of food and agriculture, 2015
Sorghum types suitable for brewing and bioethanol production are required. The effect of sorghum ... more Sorghum types suitable for brewing and bioethanol production are required. The effect of sorghum type (white non-tannin versus white type II tannin) on free amino nitrogen (FAN) production from sorghum grain and malt using exogenous protease enzymes was investigated over extended incubation at moderate temperature (45 °C). With grain in the absence of exogenous proteases, white non-tannin sorghum produced substantially higher levels of FAN than white type II tannin sorghum, due to the tannins in the latter. Incubating sorghum grain with neutral proteinase and amino-peptidase in combination improved FAN production. The two sorghum types produced similar FAN levels when malted and incubated in the absence of the exogenous proteases. When both sorghums were malted and incubated with neutral proteinase alone substantially more FAN yield (124-126 mg 100 g(-1)) occurred than with grains (61-84 mg 100 g(-1)). The combination of amino-peptidase and proteinase did not improve FAN further. Ne...
This study was conducted to determine the potential of lactoperoxidase (LP) for the diagnosis of ... more This study was conducted to determine the potential of lactoperoxidase (LP) for the diagnosis of subclinical mastitis in goats. The activities of LP and somatic cell counts (SCC) were determined in the milk of clinically healthy Saanen and South African Indigenous goats and the correlation between LP activity and SCC was measured. An increase in LP activity was observed with increasing number of somatic cells in the milk of the two goat breeds. A significantly (p < 0.01) positive correlation was observed between LP activity and SCC in the Indigenous (r = 0.91) and Saanen (r = 0.95) goat milk samples. The mean SCCs in Indigenous and Saanen goat milk samples were 2.5 × 10 4 and 2.0 × 10 6 cells/ml, respectively. The LP activity of Saanen goat milk ranged from 0.49 to 1.07 units/ml with a mean value of 0.80 units/ml. In the Indigenous goat milk, the LP activity ranged from 0.03 to 0.38 units/ml with a mean value of 0.26 units/ml. The positive correlation observed between SCC and LP activity suggests that LP may be used to detect subclinical mastitis in dairy goats.
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