The use of alkaline phosphatase and possible alternative testing to verify pasteurisation of raw milk, colostrum, dairy and colostrum-based products.

Pasteurisation of raw milk, colostrum, dairy or colostrum-based products must be achieved using at least 72°C for 15 s, at least 63°C for 30 min or any equivalent combination, such that the alkaline phosphatase (ALP) test immediately after such treatment gives a negative result. For cows' milk, a negative result is when the measured activity is ≤ 350 milliunits of enzyme activity per litre (mU/L) using the ISO standard 11816-1. The use and limitations of an ALP test and possible alternative methods for verifying pasteurisation of those products from other animal species (in particular sheep and goats) were evaluated.

Kinetics of drosopterin release as indicator pigment for heat-induced color changes of brown shrimp (Crangon crangon).

Heat-induced color changes of crustaceans are commonly described as the release of astaxanthin. In this study on Crangon crangon, it was found that astaxanthin plays a minor role in the (dis)coloration. By LC-HRMS, two polar, process dependent pigments were found.

The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products.

Raw bovine milk is highly nutritious as well as pH-neutral, providing the ideal conditions for microbial growth. The microbiota of raw milk is diverse and originates from several sources of contamination including the external udder surface, milking equipment, air, water, feed, grass, feces, and soil. Many bacterial and fungal species can be found in raw milk.

Identification and characterization of a heat-resistant protease from Serratia liquefaciens isolated from Brazilian cold raw milk.

The cold storage of raw milk before heat treatment in dairy industry promotes the growth of psychrotrophic microorganisms, which are known for their ability to produce heat-resistant proteolytic enzymes. Although Pseudomonas is described as the main causative genus for high proteolytic spoilage potential in dairy products, Serratia liquefaciens secretes proteases and may be found in raw milk samples as well. However, at the present there is no information about the proteolytic spoilage potential of S.

Thermal inactivation kinetics of proteases and polyphenoloxidase in brown shrimp (Crangon crangon).

To optimize product quality of the cooked brown shrimp (Crangon crangon), quantitative data on the influence of all relevant process parameters (treatment time and temperature) on several quality attributes is required. Surprisingly, kinetic data and models on heat induced inactivation of important endogenous spoilage enzymes of the brown shrimp are not available today. In this study the thermal inactivation kinetics of the most important spoilage enzymes, proteases and polyphenoloxidase (PPO), were determined from isothermal heat treatments of enzyme extracts of the cephalothorax.

Flexible tool for simulating the bulk optical properties of polydisperse spherical particles in an absorbing host: experimental validation.

In this study, a flexible tool to simulate the bulk optical properties of polydisperse spherical particles in an absorbing host medium is described. The generalized Mie solution for Maxwell's equations is consulted to simulate the optical properties for a spherical particle in an absorbing host, while polydispersity of the particle systems is supported by discretization of the provided particle size distributions. The number of intervals is optimized automatically in an efficient iterative procedure.

Cyclic lipodepsipeptides produced by Pseudomonas spp. naturally present in raw milk induce inhibitory effects on microbiological inhibitor assays for antibiotic residue screening.

Two Pseudomonas strains, identified as closely related to Pseudomonas tolaasii, were isolated from milk of a farm with frequent false-positive Delvotest results for screening putative antibiotic residues in raw milk executed as part of the regulatory quality programme. Growth at 5 to 7°C of these isolates in milk resulted in high lipolysis and the production of bacterial inhibitors. The two main bacterial inhibitors have a molecular weight of 1168.

Antimicrobial resistance in the food chain: a review.

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways.

Toxinogenic and spoilage potential of aerobic spore-formers isolated from raw milk.

The harmful effects on the quality and safety of dairy products caused by aerobic spore-forming isolates obtained from raw milk were characterized. Quantitative assessment showed strains of Bacillus subtilis, the Bacillus cereus group, Paenibacillus polymyxa and Bacillus amyloliquefaciens to be strongly proteolytic, along with Bacillus licheniformis, Bacillus pumilus and Lysinibacillus fusiformis to a lesser extent. Lipolytic activity could be demonstrated in strains of B.

Heterogeneity of heat-resistant proteases from milk Pseudomonas species.

Pseudomonas fragi, Pseudomonas lundensis and members of the Pseudomonas fluorescens group may spoil Ultra High Temperature (UHT) treated milk and dairy products, due to the production of heat-stable proteases in the cold chain of raw milk. Since the aprX gene codes for a heat-resistant protease in P. fluorescens, the presence of this gene has also been investigated in other members of the genus.

Seasonal influence on heat-resistant proteolytic capacity of Pseudomonas lundensis and Pseudomonas fragi, predominant milk spoilers isolated from Belgian raw milk samples.

Psychrotolerant bacteria and their heat-resistant proteases play a major role in the spoilage of UHT-processed dairy products. Summer and winter raw milk samples were screened for the presence of such bacteria. One hundred and three proteolytic psychrotolerant bacteria were isolated, characterized by API tests, rep-PCR fingerprint analysis and evaluated for heat-resistant protease production.

Development of an indirect competitive ELISA for flumequine residues in raw milk using chicken egg yolk antibodies.

To detect flumequine in raw milk, an indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed. By carbodiimide conjugation, flumequine was conjugated to cationized bovine serum albumin (cBSA-flumequine) and to cationized ovalbumin (cOVA-flumequine). For the immunization of chickens, cBSA-flumequine was used, which allowed the isolation of specific chicken egg yolk immunoglobulins (IgY) for flumequine.