Use Of Non-thermal Technologies Research Articles

Analysis of exergetic performance for a combined ultrasonic power/convective hot air dryer

Recently, the effectiveness of combined use of non-thermal technologies to improve hot air dryers’ performance from both the energy and quality point of views has been proven. However, no study has been reported on thermodynamic analysis of such hybrid systems. The present work dealt the influence of ultrasonic power combination with convective hot air dryer on exergetic performance of the system. Potato cubes were dried at different drying air temperatures (45–65 °C) and velocities (0.5–1.5 m/s) and ultrasonic powers (0–0.08 kW). Based on the findings obtained through the experiments, the exergy loss varied averagely from 240.58 to 600.83 kJ, and was decreased continuously with increasing the power level. The average exergy destruction ranged from 169.61 to 1554.23 kJ, and was decreased at the higher air temperatures and velocities. Combination of ultrasonic power with hot air intensified the exergy destruction. The average exergy efficiency varied from 24.19 to 91.42% and from 11.67 to 38.27% for the drying chamber and process, respectively.

Non-Thermal Microbial Decontamination of Onion and Dehydrated Onion Products

Onions are a major component of recipes from all-over the world. Apart from fresh onions, dehydrated onions in forms of powder, flakes and shreds are available in the market. These are used as seasonings, flavors or as condiments. Dehydrated flakes and shreds are also reconstituted and used. Dehydration is mainly done for increasing the shelf-life of the product, as well as to reduce the water weight for ease of transportation. Reduction in water activity during dehydration helps inhibit microbial growth. Nevertheless, bacterial and fungal contamination has been reported. These contaminations cause various food-borne illnesses and health hazards. Targeting spoilage and pathogenic microorganisms would not only help prevent wastage and food-borne illnesses, respectively, but also improve the quality standards as per regulations. The use of non-thermal technologies has a great potential not only in decontamination but also in the preservation of phytochemicals and volatile compounds present in onions.

Effect of nonthermal treatments on selected natural food pigments and color changes in plant material.

In recent years, traditional high-temperature food processing is continuously being replaced by nonthermal processes. Nonthermal processes have a positive effect on food quality, including color and maintaining natural food pigments. Thus, this article describes the influence of nonthermal, new, and traditional treatments on natural food pigments and color changes in plant materials. Characteristics of natural pigments, such as anthocyanins, betalains, carotenoids, chlorophylls, and so forth available in the plant tissue, are shortly presented. Also, the characteristics and mechanism of nonthermal processes such as pulsed electric field, ultrasound, high hydrostatic pressure, pulsed light, cold plasma, supercritical fluid extraction, and lactic acid fermentation are described. Furthermore, the disadvantages of these processes are mentioned. Each treatment is evaluated in terms of its effects on all types of natural food pigments, and the possible applications are discussed. Analysis of the latest literature showed that the use of nonthermal technologies resulted in better preservation of pigments contained in the plant tissue and improved yield of extraction. However, it is important to select the appropriate processing parameters and to optimize this process in relation to a specific type of raw material.

Enhancement of anti-inflammatory and antioxidant activities of prickly pear fruits by high hydrostatic pressure: A chemical and microstructural approach

Abstract Prickly pears were submitted to high hydrostatic pressure (HHP) (pressure: 100, 350 and 600 MPa; temperature: 17–34 °C; time: come-up time (CUT) and 5 min) to enhance their health potential by increasing the extractability of bioactive compounds. Phenolics, betalains and ascorbic acid were analyzed by high performance liquid chromatography (HPLC) and spectrophotometry in peels and in pulps to determine their contribution to in-vitro bowel-related antioxidant (oxygen radical absorbance capacity; ORAC) and anti-inflammatory activities (hyaluronidase inhibition and nitric oxide radical scavenging activity). Antioxidant activity in Pelota and Sanguinos pulps increased 81.1 and 68.2% at 350 MPa/5 min, respectively, and correlated with the increase of phenolic acids, isorhamnetin glucosyl-rhamnosyl-rhamnoside (IG1) and isorhamnetin glucosyl-rhamnoside (IG5). Anti-inflammatory activity increased 85.7 and 117.5% in Pelota and Sanguinos pulps, respectively, at 600 MPa/CUT and correlated with the increase of isorhamnetin glucosyl-rhamnosyl-pentoside (IG2), isorhamnetin glucosyl-pentoside (IG4) and IG5. Industrial relevance Prickly pears are potential sources of low-cost functional foods because they are rich in valuable bioactive compounds. However, these are only partially bioaccessible because they compartmentalized within cellular structures and bound to cell walls. By processing with high hydrostatic pressure, we can obtain fruit products with a higher bioactive content. This potentially enhances bowel-related antioxidant and anti-inflammatory activities. These results take us one step closer to the prevention of chronical diseases with the consumption of our everyday foods. The use of non-thermal technologies for the enhancement of health potential in vegetable foods could result in a useful tool for the development of the novel foods of the 21st century.

Non-thermal Technologies as Alternative Methods for Saccharomyces cerevisiae Inactivation in Liquid Media: a Review

The ongoing demand for high-quality processed foods which would preserve their natural and fresh-like characteristics has awakened a growing interest in non-thermal technologies. Thanks to their ability to inactivate microorganisms under mild conditions, these technologies avoid drawbacks usually attributed to the use of thermal treatments, such as nutrient loss, off-flavors, and changes in the food’s physical and chemical properties. Saccharomyces cerevisiae (S. cerevisiae) mainly causes spoilage in liquid foods with high sugar content and low pH values. Thus, it is one of the most undesirable microorganisms in the food industry since its presence may lead to important economic losses. This review offers an exhaustive compilation and critical revision of research conducted in the field of S. cerevisiae inactivation in liquid media, emphasizing the use of non-thermal technologies, such as high pressure processing, high-power ultrasound, supercritical carbon dioxide, pulsed electric fields, and others. Likewise, using these technologies in combination (the hurdle approach) may enhance their individual effect and significantly reduce the treatment time needed to obtain a given level of S. cerevisiae inactivation. In general, non-thermal technologies are proving to be able to successfully inactivate S. cerevisiae in liquid media. However, the need for further investigation and complete industrial implementation is made evident throughout this review.

Use of nonthermal technologies in the production of functional beverages from vegetable ingredients to preserve heat‐labile phytochemicals

Functional beverages (FBs) can be made from fruits and/or vegetables, and serve as a healthier alternative to sugar-rich beverages. Their periodic consumption can increase the daily intake of bioactive micronutrients like polyphenolic compounds or vitamins, which can be health promoting. However, some thermal processing methods can promote their degradation. Nonthermal methods can complement or substitute thermal ones, particularly, high-intensity pulsed electric fields, high-hydrostatic pressure, ultrasound, ultraviolet C treatment, molecular entrapment, and active packaging are promising options in this regard. These methods yield optimum results if the operational parameters are fine-tuned, with the aid of response surface methodology or similar studies. Therefore, the object of the present work is to provide an overview on the main nonthermal methods that can be used to produce FBs of good sensorial qualities, while also preserving bioactive compounds and favoring their bioaccessibility, bioavailability, and health effects. Practical applications The use of nonthermal methods in the production of functional beverages can be used to simultaneously prevent the degradation and increase the bioaccessibility and bioavailability of health-promoting vitamins (A, C, and E) and polyphenolic compounds present in the raw fruit/vegetable ingredients. While generally safe and effective, studies that focus on processing methods only consider in vitro data, which suggests the need for experiments that validate the effects of processing method on the consumer. Their continued use and study will permit their use in substitution of traditional thermal methods or in tandem to minimize their destructive effects on the molecules of interest.

The Potential of the Incorporation of Essential Oils and Their Individual Constituents to Improve Microbial Safety in Juices: A Review.

The juice sector is one of the fastest growing sectors in the food industry. Although juices are important because of their nutritional value and convenience, their composition and physicochemical properties affect their microbiological safety and overall quality during their shelf-life. Furthermore, the thermal process classically applied in juices partially reduces the occurring microflora, and the use of chemical additives is perceived negatively by consumers. For these reasons, researchers have proposed the use of nonthermal technologies as antimicrobial preservatives in juices. This paper covers the recent literature on the use of essential oils (EOs) and the individual constituents (ICs) found therein, used alone or in combination with other emerging technologies, for the preservation of juices. From this perspective, this paper discusses the growing importance of the use of EOs and their ICs, either alone or in association with other emerging technologies, in juices and their effects on the safety and physicochemical and sensory quality attributes of these products. The results of papers currently available in the literature reveal that EOs and their ICs are promising alternatives to achieve microbial safety and stability in juices. However, extensive studies considering the effects of each EO or IC on sensory characteristics, primarily taste and aroma, are still needed to establish each of these substances/compounds as feasible preservatives for use in juices. Finally, further studies could focus on the combination of low amounts of EOs or ICs with other nonthermal technologies to achieve a balance between the microbial safety and sensory acceptability of juices.

Tecnologías no térmicas en el procesado y conservación de alimentos vegetales

Durante las tres últimas décadas se ha hecho evidente una mayor preocupación por parte de los consumidores en la escala global respecto a la calidad e inocuidad de los alimentos que ofrece el mercado. En ese sentido, se denota una tendencia marcada hacia la búsqueda de productos saludables y/o que no representen riesgos significativos para la salud, y que además de ello ofrezcan una mayor frescura y practicidad a la hora de su consumo. En respuesta a esto, en un principio surgieron iniciativas orientadas a suprimir el uso de aditivos y conservantes, la mayoría basadas en procesos térmicos (pasteurización, esterilización, congelación, etc.), que si bien logran alargar la vida útil, inciden de manera directa sobre las características iniciales de los productos (frescura, textura, contenido de nutrientes, color, entre otros). En consecuencia se puso foco en la investigación y desarrollo de tecnologías de conservación que lograran mantener al máximo las propiedades naturales de los alimentos. En el caso particular de las frutas y hortalizas aparece el procesado mínimo, que combina la utilización de materiales plásticos como barrera, atmósferas modificadas (pasivas y activas), y almacenamiento refrigerado. Esta tecnología permite la obtención de productos frescos (cortados o no), pero con un periodo de vida útil limitado (7-15 días). Los avances recientes en el campo se enfocan en la utilización de tecnologías no térmicas, que logren conservar las características iniciales y la inocuidad de los productos vegetales durante un mayor periodo de tiempo, aunque también se han realizado avances en el desarrollo de tecnologías térmicas que reduzcan los efectos negativos sobre los productos tratados. Dentro de las tecnologías no térmicas se destacan los campos eléctricos pulsantes, ultrasonidos, las altas presiones hidrostáticas, irradiación, campos magnéticos oscilantes, plasma frío, luz blanca de alta intensidad, entre otros. El presente trabajo de revisión tiene como propósito el estudio de este tipo de tecnologías, poniendo énfasis en los principios básicos y su utilidad en el procesado de alimentos vegetales.

Qualitative Assessment of Sonicated Apple Juice during Storage

Apple juice was subjected to ultrasound treatment at 30, 60 and 90% amplitude levels using probe-type sonicator (20 kHz, 20C for 3 min) keeping pulse durations of 5 s on/off, and the samples were stored at 4C for 30 days. Effects of sonication and storage on total soluble solids (TSS), pH, titratable acidity, instrumental color (L*, a*, b*), nonenzymatic browning (NEB), cloud value, ascorbic acid and antioxidant capacity were evaluated. Additionally, sensory characteristics were also investigated. As results, TSS, pH and acidity remained unchanged while significant increases in color values, NEB, cloud value, ascorbic acid and antioxidant capacity were observed in all sonicated samples. Moreover, the consumer panel rated sonicated apple juice samples as most acceptable. Storage study showed significant increase in acidity, color values, NEB and decrease in pH, cloud value, ascorbic acid and antioxidant capacity. The results were further verified by principal component analysis. Practical Applications The use of nonthermal technologies for the production of fruit juices is a novel trend in food processing. Quality has always been in the spotlight because of its importance in defining customer preferences in purchasing food products. Therefore, meeting customer demands for convenience, health and sensory enjoyment are important for a product's success in the present market. The results of the present study revealed that ultrasound processing could improve and preserve more ascorbic acid, antioxidant capacity, cloud value and sensory characteristics of apple juice during storage. The technique is useful for manufacturers to produce more nutritious product with better taste and flavor than conventional methods for the benefit of consumers as they are now more conscious about health and diet.

Air-borne ultrasound application in the convective drying of strawberry

The use of non-thermal technologies, such as power ultrasound, is mostly suitable for the drying of thermolabile food materials. Thereby, the air-borne ultrasonic application as a means of improving the convective drying of strawberry has been explored in this work. Experiments were conducted by setting the acoustic power applied (0, 30 and 60W) and the air temperature (40, 50, 60 and 70°C). The desorption isotherms and the shrinkage pattern were also experimentally determined. In order to describe the drying kinetics, a diffusion model considering both convective transport and shrinkage was used.The increase in both the applied acoustic power and temperature gave rise to a significant reduction of drying time (13–44%). The application of power ultrasound involved a significant (p<0.05) improvement in the effective moisture diffusivity and the mass transfer coefficient, the effect being less intense at high temperatures. The results reported here highlight the fact that ultrasonic application during convective drying is a promising supporting technology with which to reduce the drying time needed for heat sensitive products, such as strawberry.

Analysis and Antioxidant Capacity of Anthocyanin Pigments. Part IV: Extraction of Anthocyanins

Anthocyanins are naturally occurring polyphenol compounds that impart orange, red, purple, and blue color to many fruits, vegetables, grains, flowers, and plants. In recent decades, interest in anthocyanin pigments has increased due to their possible utilization as natural food colorants and especially because their consumption has been linked to protection against many chronic diseases. It seems that anthocyanin posseses strong antioxidant properties leading to a variety of health benefits. Coupled to increasing consumer demand, food manufacturers have moved towards increased usage of approved natural colors. Despite the great potential in applications that anthocyanins represent for food, pharmaceutical, and cosmetic industries, their use has been limited because of their relative instability and low extraction percentage. Growing demands have been made on sample pretreatment, and over time some novel extraction techniques have been developed. Solid phase extraction, countercurrent chromatography, adsorption, pressurized liquid or fluid extraction, and microwave-assisted extraction are environmentally friendlier in terms of using smaller amount of solvents (often nontoxic) and reducing working time. The past few years have been characterized by wide interest in these techniques, and many contributions describing these methods have been published. The aim of this article is to review the literature available on the most important procedures proposed for the extraction of anthocyanins; the use of non-thermal technologies in the assisted extraction of anthocyanins will be covered in a separate report.

Effect of PEF, HHP and thermal treatment on PME inactivation and volatile compounds concentration of an orange juice–milk based beverage

Abstract The effects of thermal, pulsed electric field (PEF) and high hydrostatic pressure (HHP) processing on pectin methyl esterase (PME) activity and volatile compounds concentration in an orange juice–milk beverage were studied. Thermal treatment (85 °C, 1 min), PEF treatment (25 kV/cm, 65 °C) or HHP treatment (650 MPa, 50 °C) were needed to inactivate 90% of PME. Twelve volatile compounds were extracted by solid-phase microextraction (SPME) and selected for quantification by GC-MS following the application of the different treatments. The average loss in concentration of volatile compounds was between 16.0 and 43.0% after thermal treatment. After PEF treatment the average loss was between − 13.7 and 8.3% at 25 °C, 5.8 and 21.0% at 45 °C and 11.6 and 30.5% at 65 °C. After HHP treatment the average loss was between − 14.2 and 7.5% at 30 °C and 22.9 and 42.3% at 50 °C. The results showed the potential of the nonthermal technologies in providing food with a higher standard of quality compared to thermal processing. Industrial relevance The use of nonthermal technologies as an alternative to heat processing in the pasteurisation of beverages has acquired relevance in the last years. In this manuscript, we have shown that PEF treatment could achieve a high degree of PME inactivation in an orange juice based beverage, while better preserving the natural aroma than HHP and thermal treatments. PEF processing has an enormous potential to pasteurise fruit juice and preserve its natural quality characteristics.