Protein-rich by-products from the canning industry, especially dark flesh of skipjack, have limited uses due to several factors such as darken color, susceptibility to oxidation and off flavour. Protein hydrolysates from skipjack dark flesh was produced with different type of industrial proteases (Alcalase®2.4L FG, Protamex®, Neutrase®1.5MG and Flavourzyme®500MG) for 60, 120, 180 and 240 min with level of proteases used of 0.5, 1, 1.5 and 2% per weight of raw material. The degree of hydrolysis and free tryptophan content of hydrolysate were investigated. The results shows longer time with higher concentration of enzyme has increased the degree of hydrolysis. Alcalase®2.4L FG had the highest degree of hydrolysis among all proteases followed by Protamex®, Flavourzyme®500MG and Neutrase® 1.5MG. All enzymes increase free tryptophan content linearly with the increament of protease enzyme level. The longer the hydrolysis time, the higher the content of free tryptophan produced.
Traditionally, in Chinese medicine, tree peony and apple flower buds are used to prepare herbal decoctions to cure various ailments. As both of these flowers are popular and used regularly, providing scientific evidence on their basic composition is a necessity. Hence, in the present study, we report the chemical composition of these two flower buds. Results revealed tree peony and apple flower buds to have high crude protein (15.73 and 26.30%), fibre (13.11 and 16.51%), and carbohydrate (57.84 and 40.63%) contents. Both the flowers had significant amounts of essential amino acids and unsaturated fatty acids. Essential minerals present in tree peony and apple flowers were potassium (1540.37 and 1125.60 mg/100 g), calcium (462.46 and 449.98 mg/100 g), magnesium (241.51 and 164.23 mg/100 g), sodium (12.75 and 20.06 mg/100 g), and phosphorus (420.00 and 590.00 mg/100 g), respectively. Heavy metals (cadmium, nickel, mercury, lead, and arsenic) were detected in trace amounts (< 0.50 mg/100 g) in both the flower buds. Results obtained indicate that both flowers could be exploited as an additional source of nutraceutical for the development of new functional foods.
Water kefir is the product of a brown sugar solution fermented with water kefir grains. To produce starter cultures for manufacturing commercial water kefir on an industrial scale, six lactic acid bacteria (LAB), three acetic acid bacteria (AAB), and two yeast strains have been isolated from local water kefir grains, and in vitro α-glucosidase inhibitory activity has been investigated. Five of the 11 isolates (LAB [K65, K9, K67], AAB [A5], and yeast [Y6]) showed high α-glucosidase inhibitory activity. They were then tested in an in vitro gastrointestinal tract tolerance test in which all demonstrated tolerance (40‒80% survival rate). These five strains, identified as Lactobacillus mali, Lactobacillus casei, Leuconostoc mesenteroides, Gluconobacter hansenii and Saccharomyces cerevisiae; were then used to ferment water kefir beverages. The storage stability of the fermented beverage products was analysed during 28 days of storage at 4°C by measuring α-glucosidase inhibitory activity, microbial cell viability, and microbial survival in the beverage treated with simulated gastric juice. The water kefir beverage sample containing both pumpkin purée and brown sugar fermented using all five strains (109 CFU/mL LAB strains, 107 CFU/mL yeast strain, and 106 CFU/mL AAB strain) was the most suitable formulation because it achieved >50% α-glucosidase inhibitory activity and microbial survival rates of 106‒1010 CFU/mL viable LAB cells, 106‒107 CFU/mL viable AAB cells, and 105‒108 CFU/mL viable yeast cells during storage. Therefore, these five strains have potential to act as starters in the formulation of water kefir, which is an anti-hyperglycaemic beverage that can be used to manage type-2 diabetes mellitus.
In this study, we evaluated and characterized microbial cellulose produced from Kombucha after eighth day of fermentation by employing SEM, FTIR, X-ray diffractometry, adsorption isotherm, and by measuring the swelling properties. Results on SEM revealed microbial cellulose layer to be composed of a compact cellulose ultrafine network like structure. FTIR spectra showed the presence of a characteristic region of anomeric carbons (960 – 730 cm-1), wherein a band at 891.59 cm-1 confirmed the presence of β, 1-4 linkages. Results of FTIR spectra also showed microbial cellulose to be free from contaminants such as lignin or hemicellulose, which are often present in plant cellulose. X-ray diffraction studies exhibited the overall degree of crystallinity index for MCC to be slightly lower than that of microbial cellulose. Results on swelling properties indicated microbial cellulose to possess higher fiber liquid retention values (10-160%) compared to commercial MCC (5-70%). The adsorption isotherm curves showed similarities between microbial cellulose with that of pure crystalline substance. Overall, results obtained in this study were comparable with the commercial microcrystalline cellulose, indicating that the process developed by us can be explored industrially on a pilot scale.
The yield and properties of cellulose produced from bacterial fermentation of black tea broth (known as Kombucha) were investigated in this study. The tea broth was fermented naturally over a period of up to 8 days in the presence of sucrose. Tea broth with a sucrose concentration of 90 g/l produced highest yield of bacterial cellulose (66.9%). The thickness and yield of bacterial cellulose increased with fermentation time. The bacterial cellulose production increased correspondingly with increased surface area:depth ratio. Changes in pH were related to the symbiotic metabolic activities of yeasts and acetic acid bacteria, and the counts of both of these in the tea broths were relatively higher than those in the cellulose layer. Findings from this study suggest that the yield of cellulose depends on many factors that need to be optimized to achieve maximum yield.
Unprocessed ‘budu’ is a mixture of anchovies and salt that has been fermented for a period of time, and has not been heat-treated nor formulated with additional ingredients. This study analyzed Malaysian
unprocessed ‘budu’ from 12 producers for microbiological, salt, protein, histamine and 3-MCPD contents.
The results demonstrated that Malaysian unprocessed ‘budu’ were free from pathogenic Coliform, E. coli,
V. parahaemolyticus and V. cholerae contaminations. Carcinogenic 3-MCPD was below detection level of 2 ppb for all 12 samples tested. However, 58% of the unprocessed ‘budu’ had histamine content greater than the hazardous levels of 50 mg/100 g sample.
Oil palm (Elaeis guineensis Jacq.) is one of the most important commercial crops for the production of palm oil, which generates 10.88 tons of oil palm fronds per hectare of plantation as a by-product. In this study, oil palm frond fibres were subjected to an autohydrolysis treatment using an autoclave, operated at 121 °C for 20-80 min, to facilitate the separation of hemicelluloses. The hemicellulose-rich solution (autohydrolysate) was subjected to further hydrolysis with 4-16 U of mixed Trichoderma viride endo-(1,4)-β-xylanases (EC 3.2.1.8) per 100 mg of autohydrolysate. Autoclaving of palm fronds at 121°C for 60 min (a severity factor of 2.40) recovered 75% of the solid residue, containing 57.9% cellulose and 18% Klason lignin, and an autohydrolysate containing 14.94% hemicellulose, with a fractionation efficiency of 49.20%. Subsequent enzymatic hydrolysis of the autohydrolysate with 8 U of endoxylanase at 40 °C for 24 h produced a solution containing 17.5% xylooligosaccharides and 25.6% xylose. The results clearly indicate the potential utilization of oil palm frond, an abundantly available lignocellulosic biomass for the production of xylose and xylooligosaccharides which can serve as functional food ingredients.
In this study, the effects of thermosonication and thermal treatment on Escherichia coli O157:H7 and Salmonella Enteritidis in mango juice were investigated at 50 and 60°C. Besides, nonlethal injury of Salm. Enteritidis after both treatments was also examined. The highest inactivation was attained with thermosonication at 60°C. The inactivation rate was different for both pathogens, and Salm. Enteritidis was found to be more sensitive to thermosonication than E. coli O157:H7. Salmonella Enteritidis was recovered in all treated samples, except those subjected to more than 5-min thermosonication at 60°C. It was found that the introduction of high-intensity ultrasound enhanced the inactivation of pathogens compared to thermal treatment alone. On the other hand, Salm. Enteritidis was detected in a number of samples following incubation in universal pre-enrichment broth, but no growth was detected after incubation in mango juice.
Steam explosion of oil palm frond has been carried out under different temperatures between 180 and 210°C for 4 min (severity of 2.96-3.84) after impregnation of the frond chips with water or KOH solution. The effects of impregnation and steam explosion conditions of oil palm fronds on the water soluble fraction and insoluble fraction were investigated. The maximum yield of hemicelluloses in water soluble fractions recovered was 23.49% and 25.33% for water and KOH impregnation, treated with steam explosion at temperature of 210°C (severity of 3.84) with a fractionation efficiency of 77.30% and 83.32%, respectively. Under this condition, the water insoluble fractions contained celluloses at 60.83% and 64.80% for water and KOH impregnation, respectively. The steam explosion temperature of 210°C for 4 min (logR(o) 3.84) was found to be the best condition in the extraction of hemicelluloses from OPF for both types of impregnation.
Aflatoxins are highly toxic secondary fungal metabolites mainly produced by Aspergillus flavus and A. parasiticus. Human exposure to aflatoxins may result directly from ingestion of contaminated foods, or indirectly from consumption of foods from animals previously exposed to aflatoxins in feeds. This paper focuses on exposure measurement of aflatoxins and aflatoxin metabolites in various human body fluids. Research on different metabolites present in blood, urine, breast milk, and other human fluids or tissues including their detection techniques is reviewed. The association between dietary intake of aflatoxins and biomarker measurement is also highlighted. Finally, aspects related to the differences between aflatoxin determination in food versus the biomarker approach are discussed.
Aflatoxin B1 (AFB1) was detected in 57% of the nuts and nut products marketed in Penang, Malaysia using the liquid chromatography tandem mass spectrometry. The contamination levels ranged from 0.40 to 222 μg/kg and 17 out of 128 samples (13.3%) contained AFB1 above the European Commission permitted level (2 μg/kg). Estimated dietary exposure of AFB1 in nuts and nut products were 0.36 ng per kg body weight and day and 8.89 ng per kg body weight and day, representing the low and high-level of exposure, respectively. Dose-response modelling resulted in benchmark dose lower confidence limit (BMDL10) values of 0.305 ng per kg body weight and day, with the best fitted from the log-logistic model. The derived margin of exposure (MoE) values ranged from 34 to 847 suggested that AFB1 would be of public health concern and might reasonably be considered as a high priority for risk management actions.
Aflatoxins are one of the major risk factors in the multi-factorial etiology of human hepatocellular carcinoma. Therefore, the information on aflatoxins exposure is very important in the intervention planning in order to reduce the dietary intake of aflatoxins, especially among the children. This study investigated the relationship between aflatoxin B(1) (AFB(1)) lysine adduct levers in serum and socio-demographic factors and dietary intake of aflatoxins from nuts and nut products in Penang, Malaysia. A cross-sectional field study was conducted in five districts of Penang. A survey on socio-demographic characteristics was administered to 364 healthy adults from the three main ethnic groups (Malay, Chinese and Indian). A total of 170 blood samples were successfully collected and tested for the level of AFB(1)-lysine adduct. 97% of the samples contained AFB(1)-lysine adduct above the detection limit of 0.4 pg/mg albumin and ranged from 0.20 to 23.16 pg/mg albumin (mean±standard deviation=7.67±4.54 pg/mg albumin; median=7.12 pg/mg albumin). There was no significant association between AFB(1)-lysine adduct levels with gender, district, education level, household number and occupation when these socio-demographic characteristics were examined according to high or low levels of AFB(1)-lysine. However, participants in the age group of 31-50 years were 3.08 times more likely to have high AFB(1) levels compared to those aged between 18 and 30 years (P=0.026). Significant difference (P=0.000) was found among different ethnic groups. Chinese and Indian participants were 3.05 and 2.35 times more likely to have high AFB(1) levels than Malay. The result of AFB(1)-lysine adduct suggested that Penang adult population is likely to be exposed to AFB(1) but at a level of less than that needed to cause direct acute illness or death.
This randomized, double-blind, placebo-controlled, and parallel-design study was conducted to investigate the effect of a synbiotic product containing Lactobacillus gasseri [corrected] CHO-220 and inulin on the irregularity in shape of red blood cells (RBC) in hypercholesterolemic subjects. The subjects (n=32) were randomly allocated to 2 groups, a treatment group (synbiotic product) and a control group (placebo), and received 4 capsules of either synbiotic or placebo daily for 12 wk. Morphological representation via scanning electron microscopy showed that the occurrence of spur RBC was improved upon supplementation of the synbiotic. In addition, the supplementation of synbiotic reduced the cholesterol:phospholipids ratio of the RBC membrane by 47.02% over 12 wk, whereas the control showed insignificant changes. Our present study also showed that supplementation of the synbiotic reduced the concentration of saturated fatty acids (SFA), increased unsaturated fatty acids (UFA), and increased the ratio of UFA:SFA over 12 wk, whereas the control showed inconspicuous changes. The alteration of RBC membrane was assessed using fluorescence anisotropy (FAn) and fluorescence probes with different affinities for varying sections of the membrane phospholipid bilayer. A noticeable decrease in FAn of three fluorescent probes was observed in the synbiotic group compared with the control over 12 wk, indicative of increased membrane fluidity and reduced cholesterol enrichment in the RBC membrane.
Resistant starch type III (RS3 ) was produced from sago (Metroxylon sagu) and evaluated for its characteristics as a prebiotic. Two RS3 samples designated sago RS and HCl-sago RS contained 35.71% and 68.30% RS, respectively, were subjected to hydrolyses by gastric juice and digestive enzymes and to absorption. Both sago RS and HCl-sago RS were resistant to 180 min hydrolysis by gastric acidity at pH 1 to 4 with less than 0.85% hydrolyzed. Both samples were also resistant toward hydrolysis by gastrointestinal tract enzymes and intestinal absorption with 96.75% and 98.69% of RS3 were recovered respectively after 3.5 h digestion and overnight dialysis at 37 °C. Sago RS3 supported the growth of both beneficial (lactobacilli and Bifidobacteria) and pathogenic microbes (Escherichia coli, Campylobacter coli, and Clostridium perfringens) in the range of 2.60 to 3.91 log10 CFU/mL. Hence, prebiotic activity score was applied to describe the extent to which sago RS3 supports selective growth of the lactobacilli and bifidobacteria strains over pathogenic bacteria. The highest scores were obtained from Bifidobacterium sp. FTDC8943 grown on sago RS (+0.26) and HCl-sago RS (+0.24) followed by L. bulgaricus FTDC1511 grown on sago RS (+0.21). The findings had suggested that sago RS3 has the prebiotic partial characteristics and it is suggested to further assess the suitability of sago RS3 as a prebiotic material.
The in vitro fermentability of sago (Metroxylon sagu) resistant starch type III (RS(3)) by selected probiotic bacteria was investigated. Sago RS(3) with 12% RS content was prepared by enzymatic debranching of native sago starch with pullulanase enzyme, followed by autoclaving, cooling, and annealing. The fermentation of sago RS(3) by L. acidophilus FTCC 0291, L. bulgaricus FTCC 0411, L. casei FTCC 0442, and B. bifidum BB12 was investigated by observing the bacterial growth, carbohydrate consumption profiles, pH changes, and total short chain fatty acids (SCFA) produced in the fermentation media. Comparisons were made with commercial fructo-oligosaccharide (FOS), Hi-maize 1043, and Hi-maize 240. Submerged fermentations were conducted in 30 mL glass vials for 24 h at 37 degrees C in an oven without shaking. The results indicated that fermentation of sago RS(3) significantly (P < 0.05) yielded the highest count of Lactobacillus sp. accompanied by the largest reduction in pH of the medium. Sago RS(3) was significantly the most consumed substrate compared to FOS and Hi-maizes.
This study aims to determine physio-chemical properties of tempoyak, characterise the various indigenous species of lactic acid bacteria (LAB) present at different stages of fermentation and also to determine the survival of selected foodborne pathogens in tempoyak. The predominant microorganisms present in tempoyak were LAB (8.88-10.42 log CFU/g). Fructobacillus durionis and Lactobacillus plantarum were the dominant members of LAB. Other LAB species detected for the first time in tempoyak were a fructophilic strain of Lactobacillus fructivorans, Leuconostoc dextranicum, Lactobacillus collinoides and Lactobacillus paracasei. Heterofermentative Leuconostoc mesenteroides and F. durionis were predominant in the initial stage of fermentation, and as fermentation proceeded, F. durionis remained predominant, but towards the end of fermentation, homofermentative Lb. plantarum became the predominant species. Lactic, acetic and propionic acids were present in concentrations ranging from 0.30 to 9.65, 0.51 to 7.14 and 3.90 to 7.31 mg/g, respectively. Genotyping showed a high degree of diversity among F. durionis and Lb. plantarum isolates, suggesting different sources of LAB. All tested Lb. plantarum and F. durionis (except for one isolate) isolates were multidrug resistant. Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were not detected. However, survival study showed that these pathogens could survive up to 8-12 days. The results aiming at improving the quality and safety of tempoyak.
Pumpkin (Cucurbita pepo) is well known for its health and nutritional benefits and is recommended for daily consumption. This is the first report on optimization and development of fermented pumpkin-based water kefir beverage. Optimum pumpkin puree and brown sugar concentrations were found at 22.28 and 9.07% w/v, respectively, were made into a pumpkin-based beverage and fermented with water kefir grains for 24 h at 32 °C. The optimized fermented pumpkin-based water kefir beverage was found to be non-alcoholic, achieved good overall acceptability and high Lactobacillus, acetic acid bacteria and yeast cell viability of approximately 1012, 109 and 109 CFU mL-1, respectively. Overall, the optimized product attained superb technological characteristics and has the potential for industrial exploitation as a refreshing water kefir drink.