Application Of Selected Marine Microalgae In Thermoplastic Starch Production

Starch is increasingly used in many industrial applications and as a renewable energy resource. In this study, ten indigenous microalgae (freshwater and marine) were cultured and analyzed for their biochemical content. The results showed that Chlorella salina contained the highest starch of 4.92±0.33%, followed by Spirulina sp. (2.58±1.18%). Thus, C. salina and Spirulina sp. were selected to study the effects of physical and chemical factors on their starch production. C. salina produced a higher starch yield compared to Spirulina sp., (69.46 mg/L and 16.13 mg/L respectively), under optimum growth conditions of 32 ℃, red wavelength, 24L:0D (photoperiod) and 39 ppt (salinity), hence, C. salina was selected for further investigation (chemical factors). On the other hand, the efficiency of different starch extractions methods indicated that the ethanol boiling method (0.46g starch/g freezedry biomass) was significantly better than the four other methods (ultrasonic liquid shear, hotwater bath, alkaline cell lysis and bead vortexing) used. In addition, the highest and the lowest starch yield of 46.4% and 12.8% were obtained by the ethanol boiling method and alkaline cell lysis method, respectively. Thermoplastic starch (TPS) film preparation was developed using the casting technique. Thermogravimetric analysis indicated that commercial corn starch (CS) film showed higher mass loss (81.24%) compared with the algae starch (AS) film (76.53%) and melting temperatures differential scanning calorimetry (DSC) were observed to be the highest for AS film at 320.24 ℃ whereas CS showed the lowest at 317.91 ℃

Effect of detergents as antibacterial agents on biofilm of antibiotics-resistant Vibrio parahaemolyticus isolates

Vibrio parahaemolyticus (V. parahaemolyticus) is a halophilic, Gram-negative human pathogen known as a leading cause of seafood-derived food poisoning. Due to high contamination rate of seafood in Asian countries, V. parahaemolyticus is considered as a food safety concern. V. parahaemolyticus is able to produce biofilm which is more resistant toward disinfectants and antibodies than its planktonic form. Thirty six V. parahaemolyticus isolates from seafood were tested for their susceptibility using 18 different antibiotics. Two V. parahaemolyticus isolates were resistant to bacitracin, chloramphenicol, rifampin, ampicillin, vancomycin, nalidixic acid, penicillin and spectinomycin. Fourteen V. parahaemolyticus isolates were found to be resistant to bacitracin, tetracycline, rifampin, ampicillin, vancomycin, penicillin and spectinomycin. The remaining two isolates were resistant to more than 2 antibiotics. Majority of the V. parahaemolyticus isolates (97.2%) showed MAR index > 0.2, indicating that these isolates were originated from high risk sources. To investigate effect of three common detergents on antibacterial-resistant V. parahaemolyticus, 16 V. parahaemolyticus isolates resistant to more than 7 antibiotics were selected. V. parahaemolyticus (ATCC 17802) was used as reference strain. Detergents were tested for their minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) and time–kill curves were constructed to assess the concentration between MIC and bactericidal activity of detergents. Detergents D1 (Linear alkyl benzene based) was found to be the most effective with MIC and MBC ranged between 97.656 and 1562.5 μg/ml and 781.25–3125 μg/ml, respectively. The time–kill curves demonstrated that the bactericidal endpoint for resistant V. parahaemolyticus isolates reached after 30 min incubation with D1 at concentration 8 × MIC. The isolate VP003 was killed at 8 × MIC within 0.5 h and the reduction in CFU/ml was 3 log units (99.9%). V. parahaemolyticus biofilms were formed in 96 wells microtiter plates at 37 °C and 24 h-old biofilm were used to test antibacterial activity of detergents. Results showed that biofilm-producing ability of antibacterial-resistant V. parahaemolyticus isolates were inhibited at 1562.5–6250 μg/ml of D1 and eradicated at 3125 – ≥50,000 μg/ml of D1. Detergents showed potential antimicrobial activity against V. parahaemolyticus

Quantitative detection and characterization of Shiga toxin-producing Escherichia coli O157 and non-O157 in raw vegetables by MPN-PCR in Malaysia

Foodborne diseases are mainly caused by bacterial contamination which can lead to severe diarrhea. This study aimed to detect the presence of Shiga toxin-Producing Escherichia coli O157, Escherichia coli non-O157 and virulence gene in raw vegetables. The samples were purchased from wet market and hypermarket in Selangor. The detections were carried out by using the combination methods of Most Probable Number-Polymerase Chain Reaction (MPN- PCR). A total of 37(18.5%) samples were found to be contaminated by STEC. Out of these 37 isolates, four (10.8%) of the isolates were E. coli O157 while 33(89.2%) were E. coli non- O157. However, there was no E. coli O157:H7 detected in all the samples. The occurrence of Shiga toxin-Producing E. coli in edible raw vegetables samples suggests the importance of this pathogen in vegetables. Therefore, more studies are required to remove this pathogen from vegetables

Detection of Klebsiella pneumoniae in raw vegetables using most probable number-polymerase chain reaction (MPN-PCR)

Klebsiella pneumoniae (K. pneumoniae) is one of the most important members of Klebsiella genus in Enterobacteriacae family, which is responsible for pneumonia (the destructive lung inflammation disease). Vegetables are known as source of contamination with K. pneumonia. Raw vegetables are usually consumed in salads and other dishes. The aim of this study was to investigate the occurrence of K. pneumoniae in raw vegetables marketed in Malaysia. Two hundred commonly used salad vegetables (lettuces, parsley, cucumber, tomato and carrot) from hypermarkets and wet markets were investigated for presence of K. pneumoniae using Most Probable Number-Polymerase Chain Reaction (MPN-PCR). K. pneumoniae was found to be significantly more frequent (100%) and (82.5%) in lettuce and cucumbers, respectively. K. pneumoniae contamination was lowest in carrot samples (30%). All samples were contaminated with K. pneumoniae ranging from <3 to 1100 MPN/g. Results showed the high health risk associated with consumption of raw vegetables

Risk of Escherichia coli O157:H7 transmission linked to the consumption of raw milk

E. coli O157:H7 is associated with life threatening diseases such as hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Raw milk is considered a high risk food as it is highly nutritious and serves as an ideal medium for bacterial growth. The aim of this study was to investigate the prevalence of E. coli O157:H7 in raw cow, goat and buffalo milk samples. MPN-PCR method targeting the major virulence rfbE gene and fliCH 7 gene of E. coli O157:H7 was used. Total of 177 raw milk samples were collected from local dairy farms in the state of Selangor, Malaysia. The highest prevalence of E. coli O157:H7 was found in raw cow milk (8.75%) followed by raw goat milk (7.32%) and raw buffalo milk (1.79%). The estimated quantity of E. coli O157:H7 in raw cow, goat and buffalo milk ranged from <30 MPN/g to 120 MPN/g. In raw cow and goat milk samples examined contain E. coli O157:H7 microbial load ranged from 30 to 120 MPN/g and 30 to 36 MPN/g, respectively. E. coli O157:H7 microbial load in buffalo milk samples was found to be the lowest, only 30 MPN/g. Results of this research provide useful information on biosafety of E. coli O157:H7 in raw milk marketed in Malaysia

Risk assessment of acquiring listeriosis from consumption of chicken offal in Selangor, Malaysia

Listeria monocytogenes (L. monocytogenes) is an important foodborne pathogen which can cause foodborne listeriosis with high mortality rates especially in susceptible population groups such as pregnant women, elderly and immunocompromised individuals. The biosafety level of L. monocytogenes in chicken offal has becomes a great concern as chicken offal is a cheap source of protein and it is often served as side dishes in South East Asian countries. In Malaysia, the consumption of chicken offal has almost doubled from 5 g per capita per day in the early 1980s to 9 g per capita per day in 2009. In this study, risk assessment was conducted to estimate the risk of acquiring listeriosis from consumption of chicken offal in Malaysia. A microbial survey on the prevalence and concentration of L. monocytogenes in chicken offal were carried out in Selangor, Malaysia over a one-year period (November 2010 to October 2011). It was assumed that there were no seasonal changes in the prevalence and consumption pattern all year round. Assuming that 5.6 million people in Selangor, Malaysia consume a single serving (125 g) of chicken offal per week, it is estimated that in a year there could be 0.61 cases and 1.98 × 10-4 cases of listeriosis per 100,000 population of pregnant woman and immunocompromised individual, respectively. However, the potential for getting listeriosis among the healthy population was very low, only 1.39 × 10-8 cases per 100,000 population. This study demonstrated risk assessment model not only used as a tool to estimate the risk of acquiring illness but it can influence public health surveillance and providing data in setting appropriate level of protection

Prevalence and quantification of Listeria monocytogenes in chicken offal at the retail level in Malaysia.

A total of 216 chicken offal samples (chicken liver = 72; chicken heart = 72; chicken gizzard = 72) from wet markets and hypermarkets in Selangor, Malaysia, were examined for the presence and density of Listeria monocytogenes by using a combination of the most probable number and PCR method. The prevalence of L. monocytogenes in 216 chicken offal samples examined was 26.39%, and among the positive samples, the chicken gizzard showed the highest percentage at 33.33% compared with chicken liver (25.00%) and chicken heart (20.83%). The microbial load of L. monocytogenes in chicken offal samples ranged from <3 to 93.0 most probable number per gram. The presence of L. monocytogenes in chicken offal samples may indicate that chicken offal can act as a possible vehicle for the occurrence of foodborne listeriosis. Hence, there is a need to investigate the biosafety level of chicken offal in Malaysia

Transmission of Listeria monocytogenes from raw chicken meat to cooked chicken meat through cutting boards

Listeria monocytogenes (L. monocytogenes) is a food-borne pathogen contaminating poultry products. Ready-to-eat (RTE) cooked chicken meat can easily be contaminated with L. monocytogenes in post-processing activities. This study aimed to determine transmission of L. monocytogenes from raw chicken meat to hot and cooled chicken meat through polyethylene and wooden cutting boards. Raw chicken breast samples were purchased from retail markets and were artificially contaminated with L. monocytogenes at concentration of 7.35 ± 0.22 log CFU/ml. Contaminated raw samples were placed on polyethylene and wooden cutting boards to simulate bacterial transfer to cutting boards. Cooked chicken samples (hot and cooled) were then placed on the same cutting boards to simulate transfer of bacteria from cutting boards to cooked meat. L. monocytogenes successfully attached to polyethylene and wooden cutting boards and recovered after holding time up to 1 h. Transmissions of L. monocytogenes to cooled cooked samples from both types of cutting boards were relatively higher than hot cooked samples. Moreover, transfer rates of L. monocytogenes from wooden cutting boards at holding time of 1 h to both cooled and hot cooked samples were lower than those from polyethylene cutting board. It is recommended to use different cutting boards for raw and cooked materials and apply detergents and hot water for cleaning procedure to eliminate L. monocytogenes attached to the cutting boards and prevent cross-contamination of final products

Quantification of Escherichia coli O157:H7 in organic vegetables and chickens.

The organic foods’ market is becoming one of the rapidly growing sections in agricultural economies in the world. During the last two decades, food-borne outbreaks associated with fresh produce have rapidly increased. E. coli O57:H7, the caustic agent of acute hemorrhagic diarrhea and abdominal cramps, is mainly associated with meat and poultry product outbreaks but frequent outbreaks linked to the consumption of vegetables have been reported. The aim of this study was to investigate prevalence of E. coli O157:H7 in some organic foods. A total of 230 organic food samples including four-winged bean, tomato, white radish, red cabbage, chinese cabbage, lettuce, cucumber and chicken form retailed groceries and supermarkets in Malaysia were investigated. Low prevalence of E. coli O157:H7 was detected in organic vegetables and chickens. The estimated quantity of E. coli O157:H7 in all samples ranged from 2400 MPN/g. The overall MPN/g estimate of E. coli O157:H7 in the samples from organic groceries was higher than supermarket with the maximum of >2400 MPN/g. Most of the samples from supermarket showed a minimum of <3 MPN/g. The specific target genes produced amplicons of 259 bp and 625 bp after PCR amplification and E. coli O157:H7 was detected in 5.2% of total organic samples. Prevalence of E. coli O157: H7 in organic foods from groceries (8.8%) was particularly higher than supermarkets (1.0%). The highest prevalence of E. coli O157:H7 was observed in organic chickens (40%) purchased from groceries followed by four-winged bean (10%) and white radish (3.3%)