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This study reported the impact of electron beam (e-beam) treatment on microbiota and mycotoxins naturally present in red pepper powder and physicochemical quality changes. Treatment at 6 kGy indicated significant (p < 0.05) decontamination of yeasts and molds by 3.0 and 4.4 log CFU/g, respectively. A reduction of 4.5 log CFU/g of total plate counts (TPC) was observed at 10 kGy for 23 s. Fungal inactivation followed first-order kinetics while TPC better fitted with Gompertz function (R2 = 0.9912). E-beam treatment was not efficient for the degradation of aflatoxins but indirectly controlled their production by inactivation of mycotoxigenic molds. Indeed, reduction of 25% ochratoxin A was recorded at 30 kGy retaining >85% of total phenols, carotenoids and antioxidants activity. Moreover, treatment impact on total color difference (ΔE*) indicated ‘slight differences’. Overall, e-beam treatments up to 10 kGy were efficient in decontaminating the natural microbiota without detrimental effects on the physicochemical qualities of red pepper powder.
The study aimed for the analysis of the impact of pulsed electric field (PEF) pre-treatment on convection (CD) and microwave (MW-CD) assisted air drying. Drying kinetics acceleration and retention of bioactive compounds of PEF pre-treated carrots and apples has been demonstrated. Moreover, the direct and indirect environmental energy impacts of CD and MW-CD technologies with consideration of bioactive compounds preservation has been evaluated. PEF assisted CD and MW-CD demonstrated lower energy use, especially for indirect energy consumption, in the case of carotenoids preservation in dried carrots.
The influence of oil content and droplet size of oil-in-water emulsions on the heat development in an ohmic heating system was investigated. The setup was run with constant power or voltage. Emulsions consisted of sunflower oil (10–50 wt%), aqua dest. (90–50 wt%) and whey protein isolate (1.25/ 2.5/ 3.75/ 5.0 and 6.25 wt%) Two different droplet size distributions were produced, large (d0.5 ≈ 2.0 μm) and small (d0.5 ≈ 0.3 μm), for each oil mass fraction. The emulsions were ohmically heated from 10 to 80 °C at a constant power of 3.0 kW and constant voltage of 15 V/cm. The electrical conductivity decreased with an increasing oil content, resulting in longer or shorter heating time for constant voltage or constant power input, respectively. The droplet size only affected the heating process at the highest oil content.
Industrial relevance
Emulsions occur in a wide range of food products (e.g. sauces, dressings, desserts) and have properties giving structure to the food system. Ohmic heating is an emerging thermal process with improved (e.g. faster or less energy required) heating characteristics. The influence of physical changes due to different droplet sizes are of interest because these might also affect the heating characteristic. In addition, the direct comparison of two different process regulations (constant power and constant voltage) indicate which set up is expedient to a successful heating process. This study aims to identify the influence of emulsion-induced structural changes and process changes on the heating rates, which is of interest for the food industry and the related machine building industry.
Shockwaves are mechanical pressure pulses generated in liquids and gases. Based on the principles of acoustics, shockwavescan propagate through fluids such as water. At interfaces of materials with different acoustic impedances, mechanical energy is dissipated, and disintegration of biological tissue can be achieved. Physical properties as well as technical requirements for shockwave generation by electrohydraulic, electromagnetic or piezoelectric energy conversion have been reported in the literature. The use of electrohydraulic shockwaves for food treatment is an emerging food processing technology, where a lack of scientific and technical knowledge has limited further advancements in process and equipment design. In scientific literature, single aspects required for process description are available, e.g., in metallurgy, mining, air purification or particle accelerators, but their combination toward a combined model is required to characterize underlying mechanisms of action. In food, most of the studies have focused on shockwave technology for treatment of meat cuts with the purpose of reducing aging time, softening of tissue and improving its tenderness. Other applications of the shockwave technology could expand to biological inactivation, targeted texture modifications and improving extractive and refining processes in agriculture industries. Total processing costs are estimated in a range of a few Euros per ton of product. Despite being a promising alternative to existing processes used for these purposes, the application of shockwave in the food industry is limited to date to research on pilot-scale prototypes.
PEF is an innovative technology to extend the shelf life of fresh liquid food products, mainly juices, with minor impact on the quality. Many lab scale studies have been published, indicating the great potential of PEF for the juice industry. For industrial realization, the PEF systems have been adapted to the industrial requirements, establishing HACCP and hygienic design concept. Important process parameters have been identified from research and integrated in industrial PEF processes. Juice producers are now able to use PEF for their production lines.
This chapter presents the mechanism of the enhancement of freezing by means of ultrasound (US). It has been demonstrated that the effects of US are a rather complex issue. In theory, ultrasound creates cavitation bubbles throughout the volume of the product, which promotes nucleation of the ice and crushes the crystals already present in food. They can also enhance convective heat transfer to the cooling media, thereby accelerating freezing. Moreover, it has been shown that ultrasound reduces the degree of supercooling before nucleation in frozen food. Additionally, numerous experimental studies indicate that ultrasound assisted freezing is a good method to achieve homogenous crystallizations, reduce the deteriorating effect of freezing on food, and thus improve quality after thawing.
"The limits of my language are the limits of my mind. All I know is what I have words for" (Wittgenstein). When learning something completely new, we connect the unknown term to an already existing part of our knowledge. We can only build new ideas and insights upon an existing conceptual foundation. In the field of statistics, we educators frequently find ourselves met with great confusion when teaching novices. These students, entirely unfamiliar with even basic statistics, must connect the introduced statistical terms within their personal existing networks of largely non-statistical knowledge. Lecturers, on the other hand, who are well versed in statistics, have deeply internalized the content to be taught and its relevant context. The juxtaposition of the two roles may produce amusement in a lecturer upon gaining insight into the word associations made by the statistical novices. For example, a ‘logistic regression’ does not involve the ‘shipping of goods in economically difficult times,’ though this might seem entirely reasonable and intuitive to the statistics learner. Other times, these different perspectives can lead to headaches and frustration for both learners and their lecturers. In this article, we illustrate how simple statistical terms are initially connected to a student’s pre-exiting knowledge and how these associations change after completing an introductory course in applied statistics. Furthermore, we emphasize the important difference between “term”, “approach”, and “context”. Understanding this fundamental distinction may help improve the communication between the lecturer and the learner. We offer a collection of practical tools for instructors to help promote students’ conceptual understanding in a supportive, mutually-beneficial learning environment.