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The oil extraction by mechanical pressing is the most common method for continuous treatment of oleaginous seeds without solvent. Different types of presses can be used depending on the purpose (expeller, expander, and twin-screw extruder) and on the capacity range (3 kg h−1 to 150 t day−1). At the laboratory scale, many authors have highlighted the effect of operating parameters (screw rotation speed, temperature, and back pressure) and raw material (seed species, variety, water content, and pre-treatment) on process performance (oil yield and press capacity). For a given species, the main factors influencing the process are the pressure, temperature, and moisture content. The design of models mathematically describing the operation of continuous press allows to predict the behavior and performance of various presses.

During the past decade, hyperspectral imaging (HSI) has been rapidly developing and widely applied in the food industry by virtue of the use of chemometric techniques in which wavelength selection methods play an important role. This paper is a review of such variable selection methods and their limitations, describing the basic taxonomy of the methods and their respective advantages and disadvantages. Special attention is paid to recent developments in wavelength selection techniques for HSI in the field of food quality and safety evaluations. Typical and commonly used methods in HSI, such as partial least squares regression, stepwise regression and spectrum analysis, are described in detail. Some sophisticated methods, such as successive projections algorithm, uninformative variable elimination, simulated annealing, artificial neural network and genetic algorithm methods, are also discussed. Finally, new methods not currently used but that could have substantial impact on the field are presented. In short, this review provides an overview of wavelength selection methods in food-related areas and offers a thoughtful perspective on future potentials and challenges in the development of HSI systems.

Strawberries represent a valuable source of bioactive compounds including vitamin C, E, β-carotene, and phenolic compounds, but they are fruits with an extremely short postharvest life. Therefore, the current study was conducted to investigate the effectiveness of an active coating consisting in antifungal microparticles obtained by spray drying of peony extracts (Paeonia rockii (PPR)) dispersed in chitosan (Ch) and subsequent addition to polysaccharide gels to slow the fungal attack of small highly perishable fruits, such as strawberries. The results of the antimicrobial assays indicate that the peony extracts in chitosan are able to counteract effectively the growth of different fungal isolates from deteriorated strawberries. In conclusion, through the treatment with this antifungal coating, it is possible to prolong the shelf life of delicate fruits, such as strawberries, to about 16 days, slowing down the weight loss, affecting the safeguard of important vitamins and antioxidant capacity during storage, without causing any significant alteration of the nutritional and sensorial properties of the product.

The standard static gravimetric method was used to determine moisture sorption isotherms of both raw and cooked sheanut kernels at 40, 50 and 60 °C in the water activity range 0.11–0.96 in order to evaluate the influence of cooking on the moisture sorption capacity of the kernels. Preliminary analysis showed that the kernels lost a significant quantity of its proteins and carbohydrate during the cooking process. Results of analysis of the moisture sorption isotherms revealed that cooked kernels generally had significantly (p < 0.05) lower equilibrium moisture contents (EMC) than the raw ones for both desorption and adsorption processes. The effect of temperature on the sorption processes as portrayed by the desorption isotherms revealed that EMC decreased steadily with increase in temperature within the water activity range 0.10–0.8 aw but increased rapidly with increase in temperature above 0.8 aw resulting in the overlap of isotherms for all sorption processes. This crossing over of isotherms was attributed to the dissolution of sugars at higher water activities. The protein matrix in the kernel was observed using light microscopy and was found to have been disorientated after cooking. Studies using light and scanning electron microscopy revealed that the reduced ability of cooked kernels to sorb water could be linked to changes in the structure of the kernels brought about by the cooking of the kernels. It is concluded that cooking had a very significant effect on the amount of water sorbed by sheanut kernels.

This paper reports on the use of ultrasound (US) as a suitable strategy to control the growth of spoiling yeasts in fruit juices. In a first phase, US technique was tested towards Saccharomyces cerevisiae inoculated in different juices (strawberry, orange, apple, pineapple and red-fruits): the treatment was performed by modulating the level of the power (20–60 %), the duration of the treatment (2–6 min) and the pulse (2–6 s), according to a fractional design. Then, the best treatment was applied against some other spoiling yeasts (Pichia membranifaciens, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Candida norvegica). Finally, a challenge test for a commercial beverage (red-fruit juice), inoculated with Z. bailii and containing a citrus extract, was conducted evaluating the effect of US on the sensory scores of the beverage. The results showed that the effect of US was mainly influenced by the power and the duration of the treatment; on the other hand, the effect of pulse was less significant and slight. The highest reduction of S. cerevisiae was found in the following combination of the design: power 60 %/time 4 min/pulse 2 s and power 60 %/time 6 min/pulse 6 s; this result was confirmed for the other spoiling yeasts. US and citrus extract could be combined to prolong the shelf life of the red-fruit juice and control the growth of Z. bailii. The two hurdles exerted a different role and acted in different times: US reduced the initial contamination, whilst citrus extract controlled the yeast within the storage.

Differential scanning calorimetric determination of glass transition temperature in the freeze-concentrated matrix ( $$ T_{\text{g}}^{\text{'}} $$ ) of sea bass muscle was optimized. Conventional and modulated differential scanning calorimetry (DSC) techniques (using diverse cooling/heating rate and modulation parameters) and effect of an annealing step (−30, −20, or −15°C, 30min) were assayed. Transition was more evident using conventional DSC assays, cooling/heating rate: 10°C/min, annealing step at –20°C. A $$ T_{\text{g}}^{\text{'}} $$ value of –15.2 ± 0.3°C was observed for sea bass fresh muscle. This method was chosen for $$ T_{\text{g}}^{\text{'}} $$ determination on high-pressure (HP) treated and pressure shift freezing (PSF)—stored at –20°C—sea bass muscle. Thus, in both cases, transition at –15°C was less evident as a function of the pressure level applied, being very difficult to detect after treatment at 400 and 600MPa. It was observed that $$T_{\text{g}}^{\text{'}} $$ values were shifted to slightly higher temperatures (around 1°C higher) after HP treatment at 400 and 600MPa. The present work constituted a first approach to the study on the effect of HP on the glass transition of a complex food matrix, giving useful information about stability of the frozen food.