Quality Attributes of Fresh-Cut Coconut after Supercritical Carbon Dioxide Pasteurization

The impact of supercritical CO2(SC-CO2) process on the quality attributes of fresh-cut coconut has been investigated to establish the acceptability of SC-CO2treated products by the consumers. Two process conditions, previously identified as optimal to reduce the microbial content of the product, were studied: 12 MPa, 40°C, 30 min and 12 MPa, 45°C, 15 min. The results highlighted that both conditions induced some effects on product attributes. After 30 min of treatment at 12 MPa and 40°C a decrease of lightness (8%), pH (13%), fat content (24%), total phenol content (29%), flavonoid compounds (49%), antioxidant capacity (30%) and an increase of dry matter (11%) and titratable acidity (51.1%) were observed while polyphenol oxidase (PPO) exhibited 35% and 98.5% inactivation. Peroxidase enzyme activity increased by 77.8% and 30.4% at 12 MPa, 40°C, 30 min and 12 MPa, 45°C, 15 min, respectively. Sensory evaluations revealed no significant differences in appearance, texture, taste, and aroma of treated fresh-cut coconut compared to the untreated. The study confirms the feasibility of SC-CO2process for the pasteurization of fresh fruits with a firm structure and opens the door to the possibility of exploiting such a technology at industrial level

In Situ Raman Analysis of CO\u2082-Assisted Drying of Fruit-Slices

This work explores the feasibility of applying in situ Raman spectroscopy for the online monitoring of the supercritical carbon dioxide (SC-CO\u2082) drying of fruits. Specifically, we investigate two types of fruits: mango and persimmon. The drying experiments were carried out inside an optical accessible vessel at 10 MPa and 313 K. The Raman spectra reveal: (i) the reduction of the water from the fruit slice and (ii) the change of the fruit matrix structure during the drying process. Two different Raman excitation wavelengths were compared: 532 nm and 785 nm. With respect to the quality of the obtained spectra, the 532 nm excitation wavelength was superior due to a higher signal-to-noise ratio and due to a resonant excitation scheme of the carotenoid molecules. It was found that the absorption of CO\u2082 into the fruit matrix enhances the extraction of water, which was expressed by the obtained drying kinetic curve

Inactivation of Salmonella , Listeria monocytogenes and Escherichia coli O157:H7 inoculated on coriander by freeze-drying and supercritical CO 2 drying

Coriander, either fresh or inoculated with three strains of Escherichia coli O157:H7, Salmonella or Listeria monocytogenes, was treated with supercritical CO2 (scCO(2), with and without drying) or freeze-dried. After drying in scCO(2) for 150 min at 80 bar and 35 degrees C, the aerobic plate count, yeasts and molds, and the Enterobacteriaceae were reduced by 2.80, 5.03, and 4.61 log CFU/g, respectively. The total count of mesophilic aerobic spores was not significantly reduced by the treatment. Freeze-drying induced lower reductions with 1.23, 0.87, and 0.97 log CFU/g, respectively. After treatment at 100 bar and 40 degrees C without drying, inoculated strains of E. coli O157:H7, Salmonella, and L. monocytogenes were inactivated by > 7.37, > 4.73 and 4.99 log CFU/g, respectively. After drying in scCO 2 for 150 min at 80 bar and 35 degrees C, the strains were reduced by > 5.18 log CFU/g. Freeze-drying resulted in lower reduction with maximum 1.53, 2.03, and 0.71 log CFU/g, respectively. This study indicated that scCO(2) can be used for drying while offering a good inactivation of E. coli O157:H7, Salmonella, and L. monocytogenes as well as most of the bacteria in the vegetative form naturally occurring on coriander. Industrial relevance: Although dried foods are considered microbiological stable foods and show adverse conditions to microbial growth, they may still host pathogenic microorganisms, which may proliferate upon sufficient rehydration. Highly contaminated commodities such as herbs and spices can pose a threat to consumer health if not processed carefully. There is therefore a need to develop or improve drying techniques which can provide dried foods while reducing the initial contamination to acceptable levels in a single process. CO2 is a cheap, accessible solvent, with a low critical point (31 degrees C, 73.8 bar). Moreover, in the supercritical region, CO, exhibits potent microbicidal properties. Therefore, supercritical CO2 drying could be a valuable alternative nonthermal technique for conventional drying methods, such as air-drying or freeze-drying, when medium to high value-added food products with high initial contamination are involved

Exploitation of \u3ba-carrageenan aerogels as template for edible oleogel preparation.

In the current research, oleogels were prepared by using \u3ba-carrageenan aerogels as template. In particular, hydrogels containing increasing concentration (0.4, 1.0, and 2.0% w/w) of \u3ba-carrageenan were firstly converted into alcoholgel and subsequently dried by using supercritical CO2 to obtain aerogels. The latter were porous and structurally stable materials with high mechanical strength. The polymer content affected the aerogel structure: increasing the initial k-carrageenan concentration a coarser structure with larger polymer aggregates was obtained. However, the aerogel obtained at intermediate polymer concentration resulted the firmest one, probably due to the formation of a less aerated and more isotropic structure. Aerogels demonstrated a reduced capacity of water vapor sorption, remaining glassy and porous at room temperature at relative humidity lower than 60%. Aerogels showed a good capacity of oil absorption. The maximum oil loading capacity (about 80%) was obtained for aerogel containing the highest \u3ba-carrageenan content. Thus, it can be concluded that aerogels based on the structuring of water soluble polymers have potential as material for oil absorption and delivery. \ua9 2017 Elsevier Lt

Microbial inactivation of raw chicken meat by supercritical carbon dioxide treatment alone and in combination with fresh culinary herbs

The objective of the present study was to assess the potential synergistic effect between supercritical carbon dioxide (SC-CO2) and fresh culinary herbs (Coriandrum sativum and Rosmarinus officinalis) on the microbial inactivation of raw chicken meat. The microbiological inactivation was performed on Escherichia coli and natural flora (total mesophilic bacteria, yeasts, and molds). High pressure treatments were carried out at 40\ub0C, 80 or 140 bar from 15 to 45 min. Microbial inactivation had a strong dependence on treatment time, achieving 1.4 log CFU/g reduction of E. coli after 15 min, and up to 5 log after 45 min, while a pressure increase from 80 up to 140 bar was not significant on the microbial inactivation. Mesophilic microorganisms were strongly reduced (>2.6 log CFU/g) after 45 min, and yeasts and molds were below the detection limits of the technique (<100 CFU/g) in most cases. The combination of fresh herbs together with SC-CO2 treatment did not significantly increase the inactivation of either E. coli or natural flora, which was similar to the SC-CO2 alone. The synergistic effect was obtained on the inactivation of E. coli using a proper concentration of coriander essential oil (EO) (0.5% v/w), while rosemary EO did not show a significant effect. Color analysis after the treatment showed an increment of lightness (L*), and a decrease of redness (a*) on the surface of the sample, making the product visually similar to cooked meat. Texture analysis demonstrated the modification of the texture parameters as a function of the process pressure making the meat more similar to the cooked one

Effect of CO2 preservation treatments on the sensory quality of pomegranate juice

8openInternationalBothDue to the interest in identifying cost-effective techniques that can guarantee the microbiological, nutritional, and sensorial aspects of food products, this study investigates the effect of CO2 preservation treatment on the sensory quality of pomegranate juice at t0 and after a conservation period of four weeks at 4 °C (t28). The same initial batch of freshly squeezed non-treated (NT) juice was subjected to non-thermal preservation treatments with supercritical carbon dioxide (CO2), and with a combination of supercritical carbon dioxide and ultrasound (CO2-US). As control samples, two other juices were produced from the same NT batch: A juice stabilized with high pressure treatment (HPP) and a juice pasteurized at high temperature (HT), which represent an already established non-thermal preservation technique and the conventional thermal treatment. Projective mapping and check-all-that-apply methodologies were performed to determine the sensory qualitative differences between the juices. The volatile profile of the juices was characterized by gas chromatography-mass spectrometry. The results showed that juices treated with supercritical CO2 could be differentiated from NT, mainly by the perceived odor and volatile compound concentration, with a depletion of alcohols, esters, ketones, and terpenes and an increase in aldehydes. For example, in relation to the NT juice, limonene decreased by 95% and 90%, 1-hexanol decreased by 9% and 17%, and camphene decreased by 94% and 85% in the CO2 and CO2-US treated juices, respectively. Regarding perceived flavor, the CO2-treated juice was not clearly differentiated from NT. Changes in the volatile profile induced by storage at 4 °C led to perceivable differences in the odor quality of all juices, especially the juice treated with CO2-US, which underwent a significant depletion of all major volatile compounds during storage. The results suggest that the supercritical CO2 process conditions need to be optimized to minimize impacts on sensory quality and the volatile profile.openMosca, A.C.; Menghi, L.; Aprea, E.; Mazzucotelli, M.; Benedito, J.; Zambon, A.; Spilimbergo, S.; Gasperi, F.Mosca, A.C.; Menghi, L.; Aprea, E.; Mazzucotelli, M.; Benedito, J.; Zambon, A.; Spilimbergo, S.; Gasperi, F

Supercritical CO2 Pasteurization of Solid Products: a Case Study on Fresh-cut Potatoes

During the last decades, supercritical carbon dioxide (scCO2) pasteurization has been intensively studied as a potential technology to increase the safety and shelf-life of fresh food. However, the high risk of post-process contamination still represents a barrier to its industrialization. This study reports a proof of concept study in order to demonstrate the applicability of a novel method that combines scCO2 and Modified Atmosphere Packaging (MAP) for fresh-cut potatoes. The process was investigated by a full-factorial design of experiment, studying the effect of temperature (35 - 45 °C), pressure (8 – 12 MPa), and treatment time (5 – 35 min) on the microbial inactivation of E. coli and the color of the processed product. The method was able to reduce up to 1.50 Log CFU/g the load of inoculated E. coli at 45°C, 8.0 MPa and 35 min, without excessively modifying the product color. Moreover, the color did not significantly change during storage at 4 °C for 7 days

Microbial inactivation efficiency of supercritical CO2drying process

Conventional drying of spices, as hot air treatment, often needs an additional downstream inactivation step to decrease the microbial load of the dried product and improve its microbial safety and microbial quality. In this regard, the present work explored the possibility to dry and decontaminate food in a single step using supercritical carbon dioxide (scCO(2)) as a drying agent. A case study was focused on the drying of herbs and the antimicrobial effects were evaluated on the naturally present microbiota. For this purpose, experiments were carried out on coriander leaves using a high pressure vessel at 10 MPa, at two different temperatures (40 and 50 degrees C) with drying time of 0 and 150 min to establish the influence of each parameter on the microbial inactivation. Yeasts and molds appeared to be the least resistant to scCO(2) as they could never be detected after the treatment (<2 log CFU/g). Mesophilic bacteria were also significantly reduced, up to 4 log CFU/g, but remained above the limit of quantification. The quality of the dried product was comparable with the quality of air-dried samples in terms of phenolic constituents. Overall, the results indicated that scCO(2) drying was a promising green drying technique combining both drying and microbial inactivation in a single step with a relevant impact on safety and costs

Optimization of the Appearance Quality in CO2 Processed Ready-to-Eat Carrots through Image Analysis

A high-pressure CO2 process applied to ready-to-eat food products guarantees an increase of both their microbial safety and shelf-life. However, the treatment often produces unwanted changes in the visual appearance of products depending on the adopted process conditions. Accordingly, the alteration of the visual appearance influences consumers’ perception and acceptability. This study aims at identifying the optimal treatment conditions in terms of visual appearance by using an artificial vision system. The developed methodology was applied to fresh-cut carrots (Daucus carota) as the test product. The results showed that carrots packaged in 100% CO2 and subsequently treated at 6 MPa and 40 ◦C for 15 min maintained an appearance similar to the fresh product for up to 7 days of storage at 4 ◦C. Mild appearance changes were identified at 7 and 14 days of storage in the processed products. Microbiological analysis performed on the optimal treatment condition showed the microbiological stability of the samples up to 14 days of storage at 4 ◦C. The artificial vision system, successfully applied to the CO2 pasteurization process, can easily be applied to any food process involving changes in the appearance of any food product