Microbial characterization of Iranian traditional Lighvan cheese over manufacturing and ripening via culturing and PCR-DGGE analysis: identification and typing of dominant lactobacilli

This paper reports on the diversity and dynamics of the dominant microbial populations during manufacturing and ripening of Lighvan, a traditional, starter-free Iranian cheese made from raw ewe and goat’s milk as determined by culturing and PCR-DGGE. Similar dominant populations, composed of Lactococcus lactis and Lactobacillus spp. strains, were found by both techniques. However, discrepancies regarding the identity of the Lactobacillus species were encountered. Lactobacillus curvatus and Lactobacillus sakei proved to be dominant by PCR-DGGE; in contrast, Lactobacillus paraplantarum, Lactobacillus paracasei, Lactobacillus brevis and Lactobacillus plantarum were the majority cultivable organisms. RAPD typing of lactobacilli isolates showed wide genetic diversity among the species. Moreover, strain compositions change over time; L. brevis and L. paraplantarum were dominant in milk and were replaced by L. plantarum and L. paracasei strains as ripening progressed.     

Physicochemical aspects of hydrocolloid extract from the seeds of Lepidium sativum

Acid equivalent weight, intrinsic viscosity and FT‐IR measurements have demonstrated a polyelectrolyte nature to Lepidium sativum seed extract. The polyelectrolyte nature relates to the carboxyl groups carried by galacturonic acid and glucuronic acid unit. The seed extract exhibited pronounced shear thinning in steady shear rheology and a weak gel type behaviour in dynamic rheology when the concentration is high i.e. > 1%. Such behaviour suggests the ability of L. sativum seed extract to structure a liquid, thus showing the possibility of applying it as a novel thickener and stabiliser in aqueous systems. The characteristic could be due to a strong tendency of molecular association of L. sativum seed extract as found for high M/G ratio galactomannans, and possibly also the enhanced macromolecular entanglement due to relatively rigid chain conformation. Temperature dependence study showed that the rheological properties of L. sativum structured solution is stable against temperature variation.     

Steady shear flow behavior of gum extracted from Ocimum basilicum L. seed: Effect of concentration and temperature

Steady shear flow behavior of basil seed gum (BSG) was investigated between 0.5% and 2% (wt/wt) concentration and temperatures of 5-85 °C. BSG showed shear thinning behavior at all concentrations and temperatures. The Herschel-Bulkley model was employed to characterize flow behavior of BSG solutions at 0.1-1000 s⁻¹ shear rate. The pseudoplasticity of BSG increased markedly with concentration. Flow behavior of 1% BSG indicated a higher viscosity of this gum at low shear rates compared to xanthan, konjac and guar gum at similar concentration. The activation energy of BSG quantified using an Arrhenius equation increased from 4.9 × 10³ to 8.0 × 10³ J mol⁻¹ as concentration changed from 0.5% to 2% wt/wt. This indicated a heat-resistant nature of BSG. Increasing the apparent viscosity of BSG as temperature increase from 60 °C showed a sol-gel behavior of BSG based on dynamic oscillatory measurements. The static yield stress was obvious between shear rates 0.001-0.1 s⁻¹ (9.98 Pa for 1% BSG at 20 °C). The existence of the yield stress, high viscosity at low shear rates and pseudoplastic behavior of BSG make it a good stabilizer in some food formulations such as mayonnaise and salad dressing.     

Applications of hyperspectral imaging in grains and nuts quality and safety assessment: a review

Quality of foods is generally controlled with traditional methods such as microbiological and chemical tests. However, the necessity of a non-destructive, rapid and accurate on-line method to monitor the product quality and safety is the key topic of many research studies. Hyperspectral imaging (HSI) has emerged as a powerful tool to handle the afore-mentioned goals. It is a novel technique that combines simultaneous advantages of imaging and spectroscopy. HSI is an analytical method that simultaneously delivers chemical, structural and functional information from the sample. This technique can be used to analyze both individual kernels and bulk samples and simultaneously determine quality parameters of grains and nuts. Nuts and grains are nutrient dense foods with complex matrices rich in mono- and poly-unsaturated fatty acids, vegetable proteins, fiber, vitamins, minerals etc. Therefore, nuts and grains are useful dietary sources to decrease the risk of diabetes, cancer and cardiovascular disease. In this paper, recent applications of hyperspectral imaging in quality and safety inspection of nuts and grains such as classification, compositions prediction, texture analysis, and detection of varietal impurities, damages, and infections are reviewed.