Microbiology and foodborne pathogens in honey

Honey has been considered a relatively safe foodstuff due to its compositional properties, with infant botulism caused by Clostridium botulinum being the most prominent health risk associated with it. Our review is focused on the honey microflora along the food chain and evaluates the pathogenic potential of those microorganisms found in honey. This product may contain a great variety of bacteria and, particularly, fungi that eventually entered the food chain at an early stage (e.g., via pollen). For many of these microorganisms, opportunistic infections in humans have been recorded (e.g., infections by Staphylococcus spp., Citrobacter spp., Escherichia coli, Hafnia alvei, Aspergillus spp., Fusarium spp., Trichoderma spp., Chaetomium spp.), although direct infections via honey were not registered.     

Detection of Aspergillus spp. and aflatoxin B1 in rice in India

Twelve hundred rice samples consisting of paddy (675) and milled rice (525) were collected from 20 states across India. These samples were assessed for Aspergillus spp. infection on selective medium and aflatoxin B₁ (AFB1) by indirect competitive ELISA. In this investigation, Aspergillus flavus contamination dominated in all the seed samples. The other major contaminants were Aspergillus niger, Aspergillus ochraceus and Aspergillus parasiticus. Out of 1200 rice samples, 67.8% showed AFB1 ranging from 0.1 to 308.0 μg/kg. All the paddy samples from Chattishgarh, Meghalaya and Tamil Nadu showed AFB1 contamination. Milled rice grains from different states showed below the permissible levels of AFB1 (average 0.5–3.5 μg/kg). Eighty-two percent of samples from open storage that were exposed to rain showed AFB1 contamination followed by one-year-old seed. Out of 1200 samples, 2% showed AFB1 contamination above the permissible limits (>30 μg/kg). This is the first comprehensive report of aflatoxin contamination in rice across 20 states in India.     

Identification and characterisation of lactic acid bacteria isolated from traditional Urfa cheese

In this study, characterisation of dominant strains of lactic flora in traditional Urfa cheese made from sheep's milk was performed using biochemical, phenotypic and genotypic methods. According to the results obtained, the percentage distributions of the lactic acid bacteria isolated were as follows: 48.95% Enterococcus spp., 40.55% Lactococcus spp., 9.10% Lactobacillus spp., 0.69% Streptococcus spp. and 0.69% Leuconostoc spp. The majority of lactococcal isolates showed an atypical phenotype of growing in the presence of 6.5% NaCl. Acidification and bacteriocin production were also determined for each isolate. Four strains showed bacteriocin activity.     

QUALITY OF SHRIMP SOLD IN THE MARKETS OF HYDERABAD, INDIA

The quality of brackish water pond cultured shrimp purchased from wholesale markets and retail sale points at the time of sale in Hyderabad city was studied. The various hygienic practices followed during the chain of commercial operations were also studied. All the samples collected from either markets had heavy filth. Out of 35 samples collected from the wholesale markets, light filth ranged from 2% to 28%, and it ranged from 8 to 22% in retail market samples. All the shrimp samples purchased from either source contained Staphylococcus spp, and 51% of the shrimp from wholesale markets were found to be contaminated with coliforms, 11% with Salmonella spp and 5% with Vibrio spp whereas 48% of the retail market samples contained coliforms, 11%Salmonella spp and 25% had Proteus spp. None of the samples collected from either source were contaminated with Listeria spp. The extent of bacterial contamination (cfu/g) was more for the samples purchased from the retail sale points than that of the wholesale markets.     

Fungal contamination and aflatoxin content of maize,moringa and peanut foods from rural subsistence farms in South Haiti

Mycotoxins are toxic, low molecular weight compounds produced by fungi. Among them, aflatoxins are the most carcinogenic and they mainly impact on rural communities of developing countries. The present study supplies data on mycobiota and aflatoxin contamination in the most common food products consumed in Haiti. The study concerns analyses performed on 49 samples of meals and seeds collected in South Haiti and tested for fungal occurrence and aflatoxin content by HPLC-DAD technique. The results revealed that three main fungal genera affected Haitian food products: Aspergillus spp. (Section Flavi and Nigri), followed by Penicillium spp. and Fusarium spp. Aflatoxin was present in more than half of the samples of maize (Zea mays L.) kernels (55%), maize meal (57%) and moringa (Moringa oleifera Lam.) seeds (64%), and in 25% of peanut (Arachis hypogaea L.) samples. The tested food products were mostly contaminated by aflatoxin B₁ (AFB₁) followed by aflatoxin B₂ (AFB₂), while no aflatoxins type G were detected. The total concentration of aflatoxins in the positive samples was 228 μg/kg on average, i.e., fifty-seven and eleven times higher than the maximum levels allowed in Europe and USA, respectively. Both the presence of aflatoxigenic fungi and aflatoxin contamination in maize kernels seemed to be related to agricultural practices, such as weed control, irrigation and growing cycle length. These findings suggest that the Haitian population is strongly exposed to aflatoxin risk. This risk could be reduced by exploiting simple and accessible farming strategies for minimizing mycotoxin contamination, at least for maize.     

Efficacies of Garlic and L. sakei in Wine‐Based Marinades for Controlling Listeria monocytogenes and Salmonella spp. in Chouriço de Vinho,a Dry Sausage Made from Wine‐Marinated Pork

Chouriço de vinho is made from roughly minced (10 to 30 mm) pork and fat, seasoned with a marinade made from wine, salt, garlic, and other facultative seasonings used according to the recipe of each producer. The batter is maintained at 4 to 7 ºC for 24 to 48 h. It is then stuffed into natural thin pork gut, cold smoked and matured at a low temperature for 1 to 4 wk. The effect of garlic used in wine‐based marinade and a starter culture of indigenous Lactobacillus sakei on the behavior of Listeria monocytogenes and Salmonella spp. in the processing of chouriço was investigated. The garlic (as powder and fresh juice) was found to contribute (P < 0.05) to the control of both pathogens in broth. Garlic dose, as tested within the usual limits used for seasoning, did not impact the reduction of pathogens. Garlic‐wine‐based marinade and a starter culture of indigenous L. sakei contribute to controlling L. monocytogenes and Salmonella spp. in the processing of chouriço. Their presence was responsible for the loss of viability of L. monocytogenes and Salmonella spp. following 5 d of drying, even sooner than situations where no garlic was used. The results of the present work show that the use of a wine‐based marinade with garlic has an important role in ensuring the safety of the product.     

Effects of oilseed substrates (ground nyjer and flax seeds) on the growth and Ochratoxin A production by Aspergillus carbonarius

Aspergillus carbonarius is one of the major Ochratoxin A (OTA) producing fungus. Nyjer and flax seeds are important oilseeds that are used for both human and animal consumption, but they are highly susceptible to fungal growth and mycotoxin contamination. The objectives of this study were to determine the growth and OTA production by A. carbonarius on ground nyjer and flax seeds with water activity levels ranging from 0.82 to 0.98 a_w at three incubation temperatures (20, 30, 37°C). It was found that A. carbonarius was not able to grow on the two types of oilseeds with 0.82 or 0.86 a_w. Also, the fungus was not able to grow on flax seeds with high water activity (0.98 a_w). The OTA was only detected on flax seed samples with 0.94 a_w at 20°C. On nyjer seeds, the highest concentration of OTA (271 μg/kg) was detected from samples with 0.98 a_w incubated at 20°C for 5 days, while on flax seeds the highest OTA (146 μg/kg) was found on the seed samples with 0.94 a_w incubated at 20°C for 15 days. Linear regression models also indicated that 0.98 a_w was optimal for both fungal growth and OTA production on nyjer seeds. Overall, ground nyjer seed is better than flax seed to support growth and OTA production by A. carbonarius.     

Antimicrobial activity of saponin-rich fraction from Camellia oleifera cake and its effect on cell viability of mouse macrophage RAW 264.7

BACKGROUND: As a by‐product of oil production, several million tons of Camellia oleifera cake is discarded every year in China. The aim of this study was to evaluate the antimicrobial activity of a saponin‐rich fraction isolated from C. oleifera cake and investigate its effect on the cell viability of RAW 264.7, a macrophage‐like cell line present in almost all mouse tissues. RESULTS: The saponin‐rich fraction was isolated from C. oleifera cake in several steps and had a saponin content of 95.42 ± 0.10% (w/w). It showed significant inhibitory activity against the bacteria Staphylococcus aureus, Escherichia coli and Bacillus subtilis and the fungi Mucor racemosus, Aspergillus oryzae, Rhizopus stolonifer, Saccharomyces cerevisiae and Penicillium glaucum, with minimum inhibitory concentrations of 31.3, 31.3, 62.5, 250, 250, 250, 31.3 and 125 µg ml^?1 respectively. In addition, mouse macrophage RAW 264.7 pretreated with the saponin‐rich fraction (80–200 µg mL^?1) exhibited a significant loss of cell viability in a dose‐dependent manner. CONCLUSION: These results may be useful for the future application of saponins from C. oleifera cake. However, the potential use of the saponin‐rich fraction as an antimicrobial agent should be decided according to the target micro‐organisms in order to avoid causing harm in humans. Copyright © 2012 Society of Chemical Industry     

Microwave puffing‐pretreated extraction of oil from Camellia oleifera seed and evaluation of its physicochemical characteristics

In this study, Camellia oleifera oil was extracted after microwave puffing of C. oleifera seed samples by solvent, which gave a relatively high recovery of oil. To understand the extraction mechanism, the microstructures of oilseed samples were analysed with scanning electron microscopy. The HLPC, GC/MS and physicochemical characteristics of oil analysis showed that the microwave puffing pretreatment improved the amount of tocopherols in C. oleifera oil and gave a good quality of C. oleifera oil. It was concluded that the microwave puffing pretreatment of C. oleifera seed samples prior to oil extraction was a valuable alternative to the traditional pretreatments in oil industry.     

Studies on the occurrence and formation of 2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ) in various cured smoked meats,fish and cheese

Abstract : Because of the carcinogenic nature of many N-nitroso compounds, there is concern about their presence in foods. This paper presents some data on the levels of two non-volatile compounds (2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ)) in various smoked foods such as 25 cured meats, eight smoked fish and seafoods, 15 smoked poultry products, and 17 smoked cheeses. All samples were negative for HMNTHZ, but 11 of the cured meats, six poultry products and two smoked fish contained HMNTCA at levels of 10–260 μg kg^?1. Upon frying, appreciable levels of HMNTHZ were formed in only one of 10 samples of cured meat products. The smoked cheeses were all negative for HMNTCA.     

Compositional and nutritional attributes of seeds from the multiple purpose tree Moringa oleifera Lamarck

Moringa oleifera Lam is a multipurpose tree cultivated to use as a vegetable, for spice, for cooking and cosmetic oil and as a medicinal plant. Owing to the use of its seeds as food and as a clarifying agent of turbid water some nutritional and antinutritional characteristics were studied. The mature seeds contained 332.5 g crude protein, 412.0 g crude fat, 211.2 g carbohydrate and 44.3 g ash per kg dry matter. The essential amino acid profile compared with the FAO/WHO/UNU scoring pattern requirements for different age groups showed deficiency of lysine, threonine and valine. The content of methionine + cysteine (43.6 g kg⁻¹ protein), however, was exceptionally higher and close to that of human milk, chicken egg and cow's milk. The seed extract agglutinated rabbit erythrocytes but did not show trypsin inhibitor and urease activities. Feeding rats with a diet containing the seed meal showed loss of appetite, impaired growth, lower NPU and enlargement of stomach, small intestine, caecum + colon, liver, pancreas, kidneys, heart and lungs and atrophy of thymus and spleen in comparison with rats fed on an egg‐white diet. The results indicated that consumption of M oleifera raw mature seeds should be viewed with some caution until suitable processing methods are developed to abolish the yet unknown adverse factors. © 1999 Society of Chemical Industry     

荞麦籽粒的物理学特性研究

为了解荞麦籽粒的物理学特性,检测了5个荞麦品种籽、壳和仁的10个物理学特性。结果表明:籽含水率11.6%~13.4%,籽粒度3.8~5.0 mm占90%以上,仁色泽L*、a*和b*值分别约为籽的1.8,1.7,2.6倍,籽千粒重27.1~37.2 g,籽和仁容重分别为578~698,699~795 kg/m~3,籽、壳和仁比重分别约为1.11,0.61,1.13 g/cm3,壳和仁占籽重量比率分别为13.8%~19.2%,80.8%~86.2%,壳厚度约0.18 mm,壳仁间隙0.09~0.12 mm,仁硬度1.07~1.26 kg;不同品种荞麦的籽含水率和千粒重,籽仁容重,壳仁占籽重量比率,壳仁间隙及仁硬度等有较大差异。不同品种荞麦籽粒的这些物理学共性和特异性,对荞麦脱壳技术研究及脱壳生产工艺调整等有重要指导意义。     

Multiplex Real‐Time PCR Method for Detection and Quantification of Mycotoxigenic Fungi Belonging to Three Different Genera

Abstract: Cereal crop plants are colonized by many fungal species such as Aspergillus ochraceus and Penicillium verrucosum, which produce ochratoxins, and Fusarium graminearum, which produces trichothecene mycotoxins. A multiplex real‐time PCR method using TaqMan probes was developed to simultaneously detect and quantify these mycotoxigenic Fusarium, Penicillium and Aspergillus species in cereal grains. Primers and probes used in this method were designed targeting the trichothecene synthase (Tri5) gene in trichothecene‐producing Fusarium, rRNA gene in Penicillium verrucosum, and polyketide synthase gene (Pks) in Aspergillus ochraceus. The method was highly specific in detecting fungal species containing these genes and was sensitive, detecting up to 3 pg of genomic DNA. These PCR products were detectable over five orders of magnitude (3 pg to 30 ng of genomic DNA). The method was validated by evaluating sixteen barley culture samples for the presence of deoxynivalenol (DON) and ochratoxin A (OTA) producing fungi. Among the barley culture samples tested, 9 were positive for Fusarium spp, 5 tested positive for Penicillium spp, and 2 tested positive for Aspergillus spp. Results were confirmed by traditional microbiological methods. These results indicate that DON‐ and OTA‐producing fungi can be detected and quantified in a single reaction tube using this multiplex real‐time PCR method. Practical Application: This method would be helpful in detecting and quantifying the mycotoxin producing fungi such as Fusarium, Aspergillus, and Penicillium in cereal grains and cereal‐based foods.     

Microbiological and mycotoxicological analyses of processed cereal-based complementary foods for infants and young children from the German market

This study investigated several food safety criteria in 38 different commercial products of processed cereal-based foods (PCF) from the German market. Microbiological assessment, followed by 16S RNA gene sequencing of suspect colonies, included aerobic mesophilic bacteria, moulds, Enterobacteriaceae, Cronobacter spp., and presumptive Bacillus cereus. Mycotoxin analyses were performed by enzyme immunoassays for deoxynivalenol (DON), zearalenone (ZEN), T-2/HT-2 toxins (T-2/HT-2; oat containing products only), ergot alkaloids (EA), and alternariol (AOH). No violative result above existing European Union regulations or international guidelines was obtained. Most samples had very low aerobic mesophilic cell counts (<2.0 × 10¹ CFU/g), the maximum was 9.6 × 10² CFU/g. A few samples contained low numbers of opportunistic pathogens, most notably Cronobacter sakazakii, Acinetobacter spp., Pantoea spp., and enterotoxigenic Bacillus wiedmannii. Levels of mycotoxin contamination were very low, well below European Union maximum limits. DON was found in 10 samples, at levels of 9–35 µg/kg. T-2/HT-2 were found in all 15 oat-based products (1–8 µg/kg). All samples were negative for ZEN and EA. A high number (n = 25) of samples yielded weakly positive results for the nonregulated AOH (0.4–2 µg/kg), but just three samples exceeded a level of 1 µg/kg. No relationship between cereal composition and analytical findings for microbiological parameters and mycotoxins could be found. As long as PCF meals are freshly prepared and consumed immediately after preparation, the risk from sporadically occurring opportunistic bacteria appears to be minimal.     

辣木籽油食用安全性毒理学评价

以SD大鼠和昆明系小鼠为试验动物进行急性毒性、遗传毒性和30 d喂养试验,研究辣木籽油的食用安全性。结果表明:急性毒性试验未发现动物有明显中毒症状与死亡;遗传毒性试验结果均为阴性;30 d喂养试验发现当喂食含有6%、12%辣木籽油饲料的雌、雄大鼠的血糖水平显著降低,喂食含有12%辣木籽油饲料的雄性大鼠的总蛋白水平显著降低,其他各项血液生化指标均无明显变化。因此,辣木籽油是安全无毒的可食用油脂。     

Determination of flavonoids by LC/MS and anti-inflammatory activity in Moringa oleifera

Moringa oleifera is an important multipurpose tropical tree under-recognized for its nutritional and medicinal properties. Leaves of moringa collected from sub-Sahara Africa were analyzed for phenolic components by HPLC–UV–MS. Twelve flavonoids were identified, including quercetin and kaempferol glucosides and glucoside malonates as major constituents. To facilitate quantitative analysis, acid hydrolysis during extraction of moringa samples was employed to convert the conjugates into their respective flavonoid aglycones, allowing accurate quantitation of total flavonoids as aglycones. Validation of the method demonstrated recoveries ranging from 92.6% to 107.5% for the two analytes. Using this method, total flavonoids from moringa collected from Ghana, Senegal and Zambia were determined and their content ranged from 0.18% to 1.64% (g/dry weight) across the respective environment or country of production and by variety. Moringa was found to exhibit anti-inflammatory activity of constituents-rich varieties. As flavonoid malonates are among the major constituents in the original plant material, a study examining thermal stability of flavonoid malonyl derivatives showed that these compounds were not thermally stable and easily cleaved to yield their respective flavonoid glycosides.     

Indole production and deepwater pink shrimp (Parapenaeus longirostris) decomposition

Indole levels have been used to confirm the sensory evaluation of shrimp decomposition and a limit of 250 g/kg has been used in several countries to differentiate passable shrimp from shrimp in the first state of decomposition. However, no data exist on the correlation between sensory quality and indole content in deepwater pink shrimp (Parapenaeus longirostris) which validate the use of this defect level. The sensory, microbiological and biochemical changes were determined in microbiologically contaminated (4 and 7 log cfu/g ) deepwater pink shrimp stored at 0, 5, 10 and 15°C. Indole, TMA-N, TVB-N, pH, TVC, Enterobacteriaceae and Pseudomonas spp. increased with time and temperature. At low temperature storage, final indole levels in severely decomposed shrimp (TVB > 60 mg/kg) were much lower than the suggested defect level of 250 g/kg shrimp. Increased microbiological contamination (7 log cfu/g) induced faster and higher indole production at all temperatures. At higher storage temperatures, indole formation was greatly accelerated resulting in very high indole levels. High indole levels indicate decomposition; however decomposed shrimp may not necessarily contain indole. The shelf life of shrimp ranged from 15 h at 15°C to 6 days at 0°C. An indole defect level >90 g/kg shrimp should be used for deepwater pink shrimp.     

Composition and Food Potential of African Oil Bean (Pentaclethra macrophylla) and Velvet Bean (Mucuna uriens)

Fatty acids, protein and amino acids of African oil bean seed (Pentaclethra macrophylla) and velvet beans (Mucuna uriens) were studied. Crude protein of the defatted seeds were 341g and 196g per kilogram dry matter and the ether extract was 46 and 8%, respectively, for oil bean seed and mucuna. Essential amino acids composition compared fairly with that of isolated soybean protein. Lysine was high at 66.5 and 66.4g/kg crude protein (nitrogen × 6.25) for oil bean seed and mucuna, respectively. Methionine was low but cystine was high. The fat had a high content of saturated fatty acids. It is suggested that the seeds may be a potential source of protein and oil.     

OCHRATOXIN A, HYDROXYMETHYLFURFURAL AND VITAMIN C LEVELS OF SUN-DRIED GRAPES AND SULTANAS

Ochratoxin A (OTA), hydroxymethylfurfural (HMF) and l ‐ascorbic acid (vitamin C) levels were detected in sun‐dried sultanas and raisins (Vitis vinifera L. cv. Sultanina). Ochratoxins produced by Aspergillus ochraceus, Aspergillus spp., Penicillium viridicatum, Penicillium cyclopium and Rhizophus spp. The main toxin of this group is OTA. It is nephrotoxic and immunotoxic. HMF can occur during nonenzymatic browning reactions that take the form of condensation reactions between amino acids and reducing sugars. It is known as a mutagenic and carcinogenic compound. The sultanas and raisin research samples were sun dried in the field and stored over a long period in the plant. Toxicological quality patterns evaluated for OTA and HMF levels were also evaluated. These are very important compounds for food safety. They are important critical control quality criteria of sun‐dried grapes. Vitamin C was examined because of sensitivity against physical and chemical factors such as oxygen, light, thermal treatments, alkali treatment and heavy metals, as well as being important for food labeling. The mean values of OTA in sultanas and raisins were 4.64 and 2.98 µg/kg, respectively. It is determined that the studied samples could be evaluated for safety limit of OTA, which is suggested by the European Community as 10 µg/kg. The HMF values of the samples were 5.50 and 33.57 mg/kg, respectively. The raisins were sun dried. The two types of samples without any pretreatment had a long sun drying period, and they showed higher mean of HMF level with content is had showed higher mean HMF level sultanas. The HMF content is with a critical control point for human health. The mean vitamin C levels of sultanas and raisins were 3.67 and 5.15 mg/100 g, respectively. The mean vitamin C values of sultanas were lower than those of raisins. It was estimated that alkali treatment could cause the destruction of l ‐ascorbic acid. The vitamin C content of sun‐dried grapes does not contribute much to nutrition.     

Phytase and Citric Acid Supplementation in Whole-Wheat Bread Improves Phytate-phosphorus Release and Iron Dialyzability

ABSTRACT Conditions were established for maximizing phytate breakdown in whole‐wheat flour (wwf) during bread baking and for assessing the effects of dephytinization on dialyzability of intrinsic and added iron in the bread. Three different sources of phytase (Aspergillus niger, A. fumigatus, and Escherichia coli) with various levels of citric acid (0 to 6.25 g/kg wwf) were used. Supplementing citric acid at 6.25 g/kg wwf enhanced phytate degradation catalyzed by intrinsic phytase from 42% in the untreated bread to 69% (P < 0.05). Supplementation of microbial phytase (285 units/kg) plus 3.125 or 6.25 g citric acid/kg wwf further enhanced phytate reduction up to 85%. Compared with the untreated bread, citric acid alone and the combination of citric acid and phytase enhanced total iron dialyzability by 12‐ and 15‐fold, respectively, while the combination of phytase, citric acid, and ascorbic acid improved total iron dialyzability in the mixture by 24‐fold.