Effect Of Pressure Intensity Research Articles

High-pressure processing inactivation of Salmonella in raw pet food for dog is enhanced by acidulation with lactic acid

Raw pet food market is growing at rapid rate due to the raising perception as a natural option and the potential health benefits. However, raw pet food also may pose health concerns due to the occurrence of pathogenic bacteria such as Salmonella spp. High-pressure processing (HPP) is known as a non-thermal technology to inactivate microorganisms in food, preserving the nutritional characteristics with minimal impact on organoleptic traits. In this framework, the effects of pressure intensity (450–750 MPa), pressure-holding time (0–7 min) and lactic acid concentration (0–7.2 g/kg) on the inactivation of Salmonella spp. by HPP in chicken-based raw pet food intended for dogs was evaluated though a central composite design. Salmonella reduction ranged from 0.76 to > 9 log units depending on the combination of factors, which were all linearly correlated with inactivation. The rate of inactivation slowed down after an initial rapid drop of Salmonella levels during treatments, which was reflected as a quadratic term of holding time. The interaction between factors and the quadratic terms of pressure and lactic acid concentration were not statistically significant and therefore not included in the final model. According to the stochastic assessment, after treatments at 500 MPa for 4 min, the probability of a non-acidulated product being contaminated with Salmonella decreased to 0.03%. For these products, an increase in holding-time duration from 4 to 6 min at 500 MPa, decreased the probability of non-conforming products by approximately 50-fold. Remarkably, for products acidulated with 3.6 g/kg of acid lactic, the same increase in treatment duration reduced the probability of non-conforming products in approximately 475-fold. The results highlight the relevant influence of processing parameters and intrinsic factors associated with the product formulation (i.e. lactic acid causing a slight pH decrease) on the lethality of Salmonella in pressurized raw pet food. The polynomial model provided constitutes a useful decision-support tool for optimizing HPP of raw pet food, considering matrix acidulation by lactic acid as a strategy to enhance Salmonella lethality to comply with current regulations concerning pet food microbiological safety.

Improvement of gastronomical properties of duck Foie gras by high hydrostatic pressure

High hydrostatic pressure is a well-known non-thermal technology used for food pasteurization. However, this technology can be applied to purposes beyond microbial inactivation. This work is focused on the effect of high hydrostatic pressure on yield and texture of fresh foie gras for gastronomical purposes. The impact of production method of the raw material and the effects of pressure intensity and holding time are discussed based on sensory tests after expert cooking and the evidence of structural modifications in product (texture and fat loss). The attained results indicate that high pressure processing can be used, not only to extend the preservation of the product, but also to improve the texture and to increase the yield of high-quality foie gras, by decreasing fat loss during cooking. Our results evidence a more homogeneous and better behaviour of the pressurized product, with a firmer consistency and up to a 33% if improvement in cooking yield compared to untreated samples.

High hydrostatic pressure effects on membrane-related quality parameters of fresh radish tubers

The impacts of high hydrostatic pressure (HHP) treatments on metabolic functionality and quality of fruit and vegetables are still poorly understood. The effects of pressure intensity (100, 150 and 200 MPa) and holding time (5 and 10 min), and temperatures (20, 30 and 40 °C) during HHP treatment on fresh radish tubers has been studied. Colour, stiffness and turgor of the tubers were evaluated using colorimetry, texture analyses and direct turgor measurements with the cell pressure probe techniques. Comparison of turgor and stiffness losses, and colour changes, of skin and thin-walled parenchymatous inner radish tissue showed the effects of the various HHP treatment parameters on the permeability of biomembranes. HHP treatment resulted in a rapid reduction of cell turgor and, concomitantly of tuber stiffness, but also in a cellular redistribution of anthocyanins as indicated by colour changes. These responses were partially reversible up to 100 MPa applied pressure at 20-40 °C for 5–10 min, yielding a turgor threshold of 0.1 MPa. Beyond these limits, changes were irreversible, most probably due to the denaturation of membrane bound proteins such as ion channels and pumps. Overall, even short-term HHP treatments at room temperature are not suitable for sanitation by inactivating bacteria of perishable produce.

The Influence of Executive Functioning on Facial and Subjective Pain Responses in Older Adults.

Cognitive decline is known to reduce reliability of subjective pain reports. Although facial expressions of pain are generally considered to be less affected by this decline, empirical support for this assumption is sparse. The present study therefore examined how cognitive functioning relates to facial expressions of pain and whether cognition acts as a moderator between nociceptive intensity and facial reactivity. Facial and subjective responses of 51 elderly participants to mechanical stimulation at three intensities levels (50 kPa, 200 kPa, and 400 kPa) were assessed. Moreover, participants completed a neuropsychological examination of executive functioning (planning, cognitive inhibition, and working memory), episodic memory, and psychomotor speed. The results showed that executive functioning has a unique relationship with facial reactivity at low pain intensity levels (200 kPa). Moreover, cognitive inhibition (but not other executive functions) moderated the effect of pressure intensity on facial pain expressions, suggesting that the relationship between pressure intensity and facial reactivity was less pronounced in participants with high levels of cognitive inhibition. A similar interaction effect was found for cognitive inhibition and subjective pain report. Consequently, caution is needed when interpreting facial (as well as subjective) pain responses in individuals with a high level of cognitive inhibition.