The microbial profile of cheese is a primary determinant of cheese quality. Microorganisms can contribute to aroma and taste defects, form biogenic amines, cause gas and secondary fermentation defects, and can contribute to cheese pinking and mineral deposition issues. These defects may be as a result of seasonality and the variability in the composition of the milk supplied, variations in cheese processing parameters, as well as the nature and number of the non-starter microorganisms which come from the milk or other environmental sources. Such defects can be responsible for production and product recall costs and thus represent a significant economic burden for the dairy industry worldwide. Traditional non-molecular approaches are often considered biased and have inherently slow turnaround times. Molecular techniques can provide early and rapid detection of defects that result from the presence of specific spoilage microbes and, ultimately, assist in enhancing cheese quality and reducing costs. Here we review the DNA-based methods that are available to detect/quantify spoilage bacteria, and relevant metabolic pathways in cheeses and, in the process, highlight how these strategies can be employed to improve cheese quality and reduce the associated economic burden on cheese processors.

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Nucleic acid-based approaches to investigate microbial-related cheese quality defects

Biogenic amines: their importance in foods

Significance of biogenic amines to food safety and human health

Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems). The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications

Histamine fish poisoning revisited.

Validation of HPLC method for determination of tetracycline residues in chicken meat and liver

Ungerminated legume seeds (broad bean, chick pea and lupine) were contained all tested biogenic amines. Tryptamine (TRY) was the main biogenic amine detected, and its concentration considerably increased during the germination. beta-Phenylethylamine (PHE) was detected in small amounts and its concentration slowly increased during germination. The concentration of tyramine (TYR) showed a fluctuation pattern of changes during germination in all tested legumes. The concentrations of cadaverine (CAD) and putrescine (PUT) increased during the germination period in all tested grains. However, histamine (HIS) showed a fluctuated pattern of changes in both broad bean and lupine, and a gradual increase in chick pea. Spermidine (SPD) and spermine (SPM) contents of broad bean and chick pea showed a fluctuation pattern of change, while, a decrement trend of change was recorded for lupine along the germination period. By cooking, legume samples became free of biogenic amines which appeared in the boiling water. Heat treatment seems to have little effect on the concentration of biogenic amines in legume sprouts. The amounts of biogenic amines detected in the boiling water are less than the initial amounts of the sprouts (expected amounts).

Changes in biogenic amines in mature and germinating legume seeds and their behavior during cooking.

Simple, rapid and valid thin layer chromatographic method for determining biogenic amines in foods

The incidence of tetracyclines' (TCs) residue (oxytetracycline, tetracycline, chlorotetracycline and doxycycline) in fresh chicken samples (meat and liver) collected during one year was recorded. TC residues were analysed using an HPLC-DAD method. The limit of detection for meat was 4.4, 5, 10 and 7 ng g(-1) for OTC, TTC, CTC and DOC, respectively, compared with 5.5, 6, 12 and 9 ng g(-1) stated for liver. The recovery of the method ranged from 91% to 70% depending upon both matrix type and tetracycline kind. The results revealed that 66 (44%) samples contained TC residues including 21 (42%) breast, 19 (38%) thigh and 26 (52%) liver samples. The corresponding contaminated ranges were 124-5812, 107-6010 and 103-8148 µg kg(-1). A total of 12 (8%), 13 (7.33%) and 20 (13.33%) samples of breast, thigh and liver, respectively, had TC residues above the Codex maximum residue limit (MRL). Liver samples had a higher incidence and level than those found in breast or thigh samples.

A. R. Shalaby

Papers

Significance of biogenic amines to food safety and human health

Validation of HPLC method for determination of tetracycline residues in chicken meat and liver

Changes in biogenic amines in mature and germinating legume seeds and their behavior during cooking.

Simple, rapid and valid thin layer chromatographic method for determining biogenic amines in foods

Incidence of tetracycline residues in chicken meat and liver retailed to consumers.