Molecular identification of isolated fungi,microbial and heavy metal contamination of canned meat products sold in Riyadh,Saudi Arabia

Several studies have shown that canned meat products may be contaminated with fungal elements, bacteria and even heavy metals which may occur during the transportation, storage and handling processes. We conducted this study to determine the fungal, microbial and heavy metal contents of canned meats in Saudi Arabia. Of the 13 canned meat samples studied, Aspergillus and Penicillium were found in more than 70% of the total samples. Sequences of Penicillium species isolated from meat samples generated a phylogenetic tree which shows that the studied isolates were clustered in four groups. No bacterial contamination was noted in all of the samples. Nine of the 13 samples had iron concentrations above the permissible limit. All samples had zinc and copper levels below the maximum permissible limit. Four samples had cadmium levels above the maximum permissible level. All samples had levels of lead above the maximum permissible levels. These results indicate that fungal elements and higher levels of heavy metals such as lead and cadmium can be found in canned meat products. This may pose as a real danger to consumers, since canned meat products are readily accessible and convenient in Saudi Arabia.     

Metabolic profiling of the<Emphasis Type="Italic"> Arabidopsis pkl</Emphasis> mutant reveals selective derepression of embryonic traits

Embryos express several unique differentiation characteristics, including the accumulation of a number of metabolites that are generally considered to be unique to seeds. PICKLE (PKL) codes for a CHD3-chromatin remodeling factor that is necessary for repression of embryonic traits in seedlings of Arabidopsis thaliana (L.) Heynh. In pkl mutants, primary roots are capable of expressing many embryonic traits after germination and are referred to as pickle roots. In an attempt to examine the breadth of PKL-dependent repression of embryo-specific differentiation pathways, we determined the extent to which a variety of embryo-specific compounds accumulate in pickle roots. We found that pickle roots accumulate triacylglycerol with a fatty acid composition that is similar to that found in seeds. The major seed storage proteins are also present in pickle roots. In addition to these two well-characterized seed storage compounds, we observed that pickle roots accumulate phytate, a form of stored phosphate that is preferentially accumulated in seeds. Seeds of members of the Brassicaceae also accumulate a variety of unique secondary metabolites, including sinapate esters and glucosinolates. Surprisingly, the levels of secondary metabolites in pickle roots were not suggestive of an embryonic differentiation state, but did reveal that a mutation in PKL results in substantial changes in root secondary metabolism. Taken together, these data suggest that PKL is responsible for regulating some but not all aspects of the embryonic program as it relates to the accumulation of embryo-specific metabolites.Abbreviations PKL PICKLE - TAG triacylglycerol     

Effect of Sodium Nitrite on Toxin Production by Clostridium botulinum in bacon

Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 μg of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 μg of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 μg of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods.     

An overview of the factors affecting sugar content of potatoes

Potatoes destined for making chips, French fries and other fried products, need to have low sugar content to avoid browning of the finished product. The sugar content of potatoes is determined by the genotype and several pre‐ and post‐harvest factors. The major pre‐harvest factors affecting sugar content are crop maturity, temperature during growth, mineral nutrition and irrigation, while important post‐harvest factors are mechanical stresses and storage conditions. Each genotype requires an ideal pre‐and post‐harvest treatment to maintain low sugar levels; any kind of stress results in sugar accumulations.     

SENSORY QUALITY STUDIES ON MANGO AROMA CONCENTRATE DURING STORAGE

Aroma concentrates from Alphonso and Totapuri mango pulps were prepared and the aroma stripped pulps were concentrated two folds. Ready to serve beverages were prepared from fresh mango pulps and pulp concentrates by adding different levels of aroma concentrates. Sensory evaluation of beverages showed that in the case of Alphonso mango addition of 50%, 75% and 100% aroma concentrate gave comparable quality while with Totapuri only 50% level showed comparable quality. The aroma stripped pulp concentrates were canned as such and after mixing with 50% aroma concentrates and stored at 25 × 5°C. Aroma concentrates were bottled and stored at 2°C. At different intervals of storage, beverages were prepared and evaluated. The results showed that throughout the storage period, beverages prepared from mango concentrates to which 50% aroma was added before canning was superior to those prepared from aroma stripped canned pulp concentrates to which aroma was added at the time of preparation of beverage indicating the effect of mango pulp on aroma stability.     

Changes in Resident Bacteria, pH, Sucrose, and Invert Sugar Levels in Sugarbeet Roots During Storage

Stored sugarbeet roots began fermenting within 24 h after oxygen was depleted at 26 C when the resident bacterial populations increased dramatically. Most of the bacteria present after anaerobic storage for 7 days at 26 C could hydrolyze sucrose in vitro. Although pH and sucrose levels decreased and invert sugar levels increased with time in aerobic storage at 26 C, these processes were significantly accelerated in beets stored anaerobically at 26 C. Under oxygen-depleted storage conditions at 26 C, the sucrose content was almost completely lost after 21 days.     

Comparative analysis of chemical,mineral and in-vitro antibacterial activity of different varieties of date fruits from Saudi Arabia

Three important varieties of dates (Sukri, Barhi, and Rothana), grown in Saudi Arabia were analyzed for their chemical, mineral and anti-bacterial activity. Among all the varieties analyzed, the Sukri dates had the highest moisture (16%), carbohydrate (80.65 mg/g) and the phenolic content (1.24 mg GAE/100 g) whereas, the ash content was the lowest (2.22%). The mineral content analyzed by ICP OES reveals that all three varieties contain an appreciable amount of essential macro and micro nutrients. They contain a good amount of potassium; the maximum amount of K (8171.24 mg/kg) was recorded in Barhi dates. Besides that, all three varieties of dates contain a good amount of Se, Cu, P, Fe, Mn. The comparative analysis of the GC MS chromatogram reveals that there were only five compounds that were present in all three varieties. The bioactive compounds Mannoic and Lactone were detected in all three varieties. The fruits contain some important groups of sugar, alcoholic sugar, aromatic hydrocarbon, phenol(s) and esters. The extracts of dates were assed for their antibacterial activity against 6 important strains of human pathogenic bacteria. The strains of E. coli-ATCC25922, B. subtilis-ATCC6633, S. aureus-ATCC25923, were observed to be highly sensitive to most of the extracts whereas S. pyogenes and S. flexeneri (clinical isolates) showed moderate sensitivity to some extracts. The variety Sukri was found to be superior to the other two varieties in terms of sugar and phenolic contents, in addition, the methanol extract of Sukri dates showed excellent antibacterial activity against most of the bacteria evaluated. These varieties of dates prove to have immense potential to be utilized as a therapeutic agent for curing mineral deficiency also can be explored for developing antibacterial agents.     

Protein modification by Amadori and Maillard reactions during seed storage: roles of sugar hydrolysis and lipid peroxidation

The non-enzymatic modifications of proteins through Amadori and Maillard reactions play an important role in the loss of seed viability during storage. In the present study, the contribution of sugar hydrolysis and lipid peroxidation to Amadori and Maillard reactions, and to seed deterioration was investigated in mung-bean (Vigna radiata Wilczek). The contents of glucose and lipid peroxidation products in seed axes increased significantly during storage. The accumulation of Amadori products in seed axes was correlated to the lipid peroxidation, whereas the accumulation of Maillard products was closely correlated to sugar hydrolysis. The rate of accumulation of Maillard products was not well correlated to the content of Amadori products in both seed axes and protein/glucose model system, reflecting the complex nature of Amadori and Maillard reactions. The content of Amadori products in seed axes increased during the early stages of seed ageing, whereas the content of Maillard products increased steadily during the entire period of storage. The accumulation of Maillard products in seed axes was associated with the decline of seed vigour. These data suggest that, during seed ageing, sugar hydrolysis and lipid peroxidation are coupled with non-enzymatic protein modification through Amadori and Maillard reactions.     

An alternative infrared spectroscopy assay for the quantification of polysaccharides in bacterial samples

The ability of bacteria to produce extracellular polysaccharides has been regarded as an indication of biofilm-forming capacity. Therefore, the determination of the sugar content in bacterial samples becomes a significant parameter. The colorimetric methods currently used are rather sensitive to the nature of the sugars and therefore require knowledge of the sugar types present in the samples. Unfortunately, the types of sugars present in bacteria are generally unknown and often composed of a complex mixture. In this article, we propose an alternative method based on Fourier transform infrared (FTIR) spectroscopy for the estimation of the total sugar content in bacterial samples. The method is based on a systematic treatment of FTIR spectra obtained from dried bacteria samples. It is assumed that the total sugar amount can be estimated from the area of characteristic bands between 970 and 1182 cm(-1). In parallel, the amide II band (1560-1530 cm(-1)) associated with proteins, or the C-H stretching region (2820-3020 cm(-1)) associated with the biomass, can be used for normalization purposes. Therefore, the ratio of the band area in the sugar window over that of the amide II or C-H stretching can be used to report the sugar content in bacterial samples. This method has been validated on model bacterial mixtures containing sugars, proteins, and DNA. Results with real bacterial samples are also provided and show conclusively that increased sugar contents in biofilms can be identified. The proposed FTIR approach requires minimal sample preparation and a single acquisition, is rapid, and may be applied to any kind of bacterial growth.     

Determination of endotoxins in sugar with the Limulus test.

The Limulus amebocyte lysate test has been used for determination of pyrogens in sugar of different qualities. All the samples of domestic white sugar and beet raw sugar produced in Sweden during 1976 had a very low content of endotoxins, less than 10 ng/g of sugar. Imported cane raw sugar was, however, highly contaminated. The highest value obtained corresponds to about 100 mg of Escherichia coli endotoxin per g of raw sugar. Such crude sugar cannot, even after refining, be used for medical purposes. Instead, Swedish beet sugar is used as the raw material for production of invert sugar solutions for parenteral administration. The amount of endotoxin in this sugar is less than 1 ng/g.     

Examination of conditions inhibiting the formation of acrylamide in the model system of fried potato

Acrylamide (AAm) is produced in food through the reaction of asparagine and reducing sugar. We examined several methods of reducing the level of AAm using potato tubers. The fried model system that we employed consisted of thin slices that were first treated in water under different conditions before frying. A sufficient amount of water present in the fry material acts as an inhibitor against the formation of AAm and allows only a negligible amount of AAm to form. It was found that given the low content of water, the fry material temperature was sufficiently high to allow a relatively large level of AAm to form. Examination of water treatment prior to frying revealed that higher-temperature treatment water and longer treatment time resulted in the formation of lower levels of AAm. Moreover, removing some of the residual heat had an inhibiting effect on the formation of AAm.     

Determination of endotoxins in sugar with the Limulus test

The Limulus amebocyte lysate test has been used for determination of pyrogens in sugar of different qualities. All the samples of domestic white sugar and beet raw sugar produced in Sweden during 1976 had a very low content of endotoxins, less than 10 ng/g of sugar. Imported cane raw sugar was, however, highly contaminated. The highest value obtained corresponds to about 100 mg of Escherichia coli endotoxin per g of raw sugar. Such crude sugar cannot, even after refining, be used for medical purposes. Instead, Swedish beet sugar is used as the raw material for production of invert sugar solutions for parenteral administration. The amount of endotoxin in this sugar is less than 1 ng/g.     

Interactions of rubidium, sodium, and potassium on the nutrition of sugar beet plants

The effect of Rb on the growth and the development of sugar beet plants (Beta vulgaris, var. MS NB1 × NB4) depends on the Rb concentration, the K supply, and the relative abundance of Na. Rubidium added either to a low or high K solution with or without added Na increased leaf blade size greatly, possibly through an effect on phytohormones or through a “partitioning effect” on the distribution of carbohydrates, with top growth favored over storage roots.     

The microflora of semi-preserved fish products III. Principal groups of bacteria occurring in tibits

Bacterial cultures isolated from semi-preserved fish products (i.e. titbits) and believed to be of major importance in the spoilage of the product, were examined and classified. Three groups were found. One group belonged to the family Micrococcaceae, containing strains from the generaMicrococcus andStaphylococcus. The remaining two groups belonged to the family Lactobacteriaceae, comprising two species of the genusPediococcus and heterofermentative species of the generaLactobacillus andLeuconostoc.     

Characterization of Lactic Acid Bacteria Coexisting with a Nisin Z Producer in <Emphasis Type="Italic">Tsuda</Emphasis>-Turnip Pickles

Bacteriocin-producing lactic acid bacteria (LAB) are believed to be associated with many types of fermented food. The present study reports the identification of lactic acid bacterium MS27 producing a bacteriocin isolated from the Tsuda-turnip pickle, which is a Japanese fermented food, and characterization of LAB coexisting with the bacteriocin producers in the Tsuda-turnip pickle. The strain MS27 was identified as Lactococcus lactis subsp. lactis based on a partial 16S rRNA gene sequence and sugar fermentation pattern analyses. Mass spectroscopy and genetic analysis revealed that it produces nisin Z. Microbial population analysis revealed that the LAB community in the Tsuda-turnip pickle comprises nisin Z-sensitive and nisin Z-insensitive LAB (nonbacteriocin producers) and nisin Z producers at population rates of 52.5%, 37.5%, and 10.0%, respectively. This revealed that Leuconostoc spp. (nisin Z insensitive) is the dominant species among LAB microflora and that nisin Z insensitivity of a bacterial strain is proportional to its ability to dominate the population in Tsuda-turnip pickles. Competitive growth assay revealed that Leuconostoc spp. considerably suppressed the bacteriocin production of L. lactis MS27. These results suggested that Leuconostoc spp. contributes to the formation of the LAB community with a wide variety of microorganisms in Tsuda-turnip pickles.     

Effects of intracellular trehalose content on Streptomyces griseus spores.

The disaccharide trehalose is accumulated as a storage product by spores of Streptomyces griseus. Growth on media containing excess glucose yielded spores containing up to 25% of their dry weight as trehalose. Spores containing as little as 1% of their dry weight as trehalose were obtained during growth on media containing a limiting amount of glucose. Spores containing low levels of trehalose accumulated this sugar when incubated with glucose. The increase in trehalose content coincided with increases in spore refractility, heat resistance, desiccation resistance, and the time required for spore germination in complex media. Trehalose is accumulated by a wide variety of actinomycetes and related bacteria and may be partially responsible for their resistance properties.     

A review of cellular structure,starch, and texture qualities of processed potatoes

Certain combined characteristics of cellular structure and starch properties provide distinctions between varieties of potatoes and bear strong relation to their culinary qualities. Larger tissue cells and larger average starch granules are associated with mealiness. Smaller cells and starch granules characterize the less mealy and “waxy” varieties. Similarly, the same general relationships hold for the varietal characteristics of high vs. low solids and high vs. low starch contents. Within a variety, proportionately larger numbers of large starch granules are associated with tubers of high specific gravity, and more smaller granules, with low specific gravity. There also is a distinct reduction in percent of small granules during storage of tubers. Differences in starch granule size are accompanied by differences in amylose and amylopectin. Small granules contain less amylose and gel at higher temperatures than do the larger starch granules. Amylose content likewise appears to be a varietal characteristic. These variations in amylose content reflect fundamental differences in the properties of the starch gels formed when different varieties of potatoes are cooked. Likewise, there are similar distinctions between the starches within different tissue zones of individual tubers. Cell size also varies characteristically within different tuber regions. Starch gel properties may be manipulated during processing by such treatments as precooking-heating, chilling, freezing, and thawing. These treatments provide some measure of control of textural quality in the finished product. Additives such as stearates or glycerides complex readily with amylose and also influence gel properties and texture in processed potato products. Sucrose accumulated during tuber storage also may increase gel strength and influence texture. Varietal differences in cell structure and in starch granule size and composition offer opportunities for genetic exploitation. The merits of special processing for texture control vs. development of varieties for specific processed product qualities are briefly discussed.     

The preservation unaltered,of mineral nitrogen in tropical soils and soil extracts

Summary Experiments have been conducted on different methods of storing soils and soil extracts to preserve the mineral-N status unaltered. Neither the addition of chemicals at the rates used nor storage at sub-zero temperatures were found to preserve the mineral-N status of the soils completely unaltered over short periods of time. Furthermore, evidence was found to show that storage at sub-zero temperatures can effect subsequent mineralization of nitrogen during incubation.The mineral-N content of soil extracts prepared with an acidified K₂SO₄ reagent was not preserved over short periods by the addition of chemicals, by storing the extracts at sub-zero temperatures or by the addition of copper ions to the extracting solution. The mineral-N content of soil extracts prepared with a neutral KCl reagent could be preserved during storage at subzero temperatures but the addition of copper ions to the extracting reagent was not effective.Changes in the mineral-N content of both soils and soil extracts during storage were not consistent and in the soils appeared to be related to biological activity and the concentration of mineral N present. In soil extracts changes appeared to be related to the concentration of mineral-N present and to some other factor(s).Part of a thesis submitted for the degree of Ph. D in the University of East Africa.     

Changes in content of sugars and their exosmose from maize kernels in relation to cold resistance

Changes in soluble sugar content in individual parts (embryo, endosperm and pericarp) of maize caryopses exposed to the influence of 24°, 10° and 6° were studied. At the same time the eluates from sand in which the seeds were planted and exposed for various periods were analysed by paper chromatography. It was found that the lower was the temperature of exposure the greater were the amounts of sucrose, glucose, raffinose and other sugars diffused from the caryopses into the medium before the start of germination. The exosmose course and the changes in sugar content in kernel tissues proved that the hydrolysis of storage polysaccharides is not inhibited by low temperatures but that under such conditions the use of products of hydrolysis for the growth of the embryo is inhibited. It is concluded that not only surface parts of endosperm but also the embryo participates in exosmose. The relatively high sugar exosmose found from seeds germinated at low temperatures explains the well-known interaction of pathogenic and parasitic microorganism in cold resistance during emergence.     

Influence of oligosaccharides on the growth and tolerance capacity of lactobacilli to simulated stress environment

Aims:  Lactobacilli should resist stress environments in industry process and gastrointestinal tract before exerting their beneficial effects. To explore the possible stabilizers in probiotic products, prebiotic oligosaccharides were investigated.
Methods and Results:  We investigated the effect of four selected oligosaccharides on the survival of probiotic Lactobacillus plantarum and L. acidophilus to simulated stress conditions. It was found that the tolerance of lactobacilli to simulated artificial gastrointestinal juice, heat treatment and phenol solution was obviously enhanced in fructo-oligosaccharides (FOS) and xylo-oligosaccharides (XOS) group. In addition, chito-oligosaccharides (COS), manno-oligosaccharides (MOS) and glucose also had positive effect compared with control group (without sugar).
Conclusions:  Prebiotic oligosaccharides, especially XOS and FOS added in medium have protection function to lactobacilli in stress environments. The protection function of oligosaccharides may correlate with the bacteria growth, which was stimulated by these oligosaccharides.
Significance and Impact of the Study:  Prebiotic oligosaccharides may be used as stabilizers in probiotic products.