Fernanda B. Campagnollo

Impact of Unit Operations From Farm to Fork on Microbial Safety and Quality of Foods

Unit operations modify material properties aiming to produce uniform and high-quality food products with greater acceptance by the increasingly demanding consumers or with longer shelf life and better possibilities of storage and transport. Microorganisms, including bacteria, molds, viruses, and parasites, may have different susceptibilities to unit operations employed during food processing. On-farm (cleaning, selection and classification, cooling, storage, and transport) and on-factory unit operations (heating, refrigeration/freezing, dehydration, modification of atmosphere, irradiation, and physical, chemical, and microbial-based operations) are commonly employed throughout food production chain. The intensity and combination of unit operations along with food composition, packaging, and storage conditions will influence on the dominance of specific microorganisms, which can be pathogenic or responsible for spoilage. Thus, in the context of food safety objective (FSO), the knowledge and the quantification of the effects caused by each step of processing can enable to control and ensure the quality and safety of manufactured products.

Survival variability of 12 strains of Bacillus cereus yielded to spray drying of whole milk

The variability in spore survival during spray drying of 12 Bacillus cereus strains was evaluated. B. cereus spores were inoculated on whole milk (7.2 ± 0.2 log10 spores/g dry weight) and processed in a spray-dryer. Twelve independent experiments were carried out in triplicate. The spore count was determined before and after each drying process, based on the dry weight of whole milk and powdered milk. Then, the number of decimal reductions (γ) caused by the spray drying process was calculated. B. cereus strains presented γ values ranging from 1.0 to 4.7 log10 spores/g dry weight, with a high coefficient of variation (CV) of 46.1%. Cluster analysis allowed to group B. cereus as sensitive (strains 511, 512, 540, 432 and ATCC 14579), intermediate (strains B18, B63, and B86) and resistant strains (strains B3, B94, B51 and 436). Three strains (one of each group) were selected for further investigation and characterization of their physicochemical and molecular (proteomics) differences. Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) were used to determine physicochemical characteristics and glass transition temperature (Tg), respectively. No differences in signs among the three strains were found in spectra ranging from 900 to 4000 cm-1. The endothermic peak ranged between 54 and 130 °C for strain 540; between 81 and 163 °C for strain B63; and between 110 and 171 °C for strain 436. However, they showed different Tg: 88.82 °C for strain 540; 114.32 °C for strain B63; and 122.70 °C for strain 436. A total of eleven spots were identified by mass spectrometry, with the spore coat protein GerQ, sporulation protein YtfJ (GerW), and peptidyl-prolyl cis-trans isomerase being found in at least two strains. Altogether, the results suggested that the high survival variability of B. cereus spores to the spray drying process seems to be mainly associated with different Tg and protein content. The study highlights the importance of quantifying the effects of this unit operation over the target microorganisms. These data may be relevant for the development of effective measures aiming to control the occurrence of B. cereus in milk powder as well as to reduce spoilage or safety issues associated with the presence of this bacterium in foods, particularly those formulated with milk powder.

9 – Food Safety

Food safety, in general terms, concerns every step of food production from farm to fork. Owing to several factors, such as changes in demographical and social conditions, access to information, and better understanding of what are healthy foods, people from all around the world are demanding high-quality and safe food products. Apart from the sensorial characteristics, the final products must be free of external contaminants. These contaminants could be potentially harmful to the final consumer, being classified as biological, chemical, and physical hazards. Therefore, this chapter presents an overview of the main food-borne hazards, the current context of food safety, food safety concepts throughout the food production chain, and the role of regulatory agencies in food safety.