EFECTO DEL PROCESADO POR MICROONDAS EN LAS CARACTERÍSTICAS SENSORIALES DE UN PURÉ DE KIWI

En este trabajo se ha evaluado el efecto de las condiciones de procesado por microondas, aplicando tratamientos suaves, en las características del puré de kiwi. Se aplicaron diferentes combinaciones potencia de microondas - tiempo de proceso y se realizaron medidas sensoriales e instrumentales, con el objetivo de establecer una correlación entre ambas. Para las pruebas sensoriales, en primer lugar se entrenó a un panel de catadores con el objetivo de realizar un análisis sensorial descriptivo del producto. El análisis instrumental de las muestras consistió en medir la consistencia, viscosidad, color y características fisicoquímicas del puré fresco así como del puré tratado. La aplicación de microondas a niveles de potencia, tiempos o una combinación de estos dos factores que dé lugar a tratamientos de una cierta intensidad (600 W-340 s, 900 W-300 s y 1000 W-200 s), afecta principalmente al color y sabor del producto, de manera que se obtienen muestras más consistentes, con sabor atípico y con un color más diferente al del kiwi, consecuencia de un aumento de la claridad y de cambios hacia tonalidades más amarillo-verdosas. Para la evaluación instrumental del color y consistencia percibidos visualmente en este producto, los parámetros más indicados, entre los considerados en este estudio, serían las coordenadas de color L*, a* y el ángulo de tono y la distancia de avance medida con el consistómetro Bostwick.Benlloch Tinoco, M. (2010). EFECTO DEL PROCESADO POR MICROONDAS EN LAS CARACTERÍSTICAS SENSORIALES DE UN PURÉ DE KIWI. http://hdl.handle.net/10251/13665Archivo delegad

Impact of heterogeneously crosslinked calcium alginate networks on the encapsulation of β-carotene-loaded beads

This study investigated the impact of heterogeneity of crosslinking on a range of physical and mechanical properties of calcium alginate networks formed via external gelation with 0.25–2% sodium alginate and 2.5 and 5% CaCl2. Crosslinking in films with 1–2% alginate was highly heterogeneous, as indicated by their lower calcium content (35–7 mg Ca·g alginate−1) and apparent solubility (5–6%). Overall, films with 1–2% alginate showed higher resistance (tensile strength = 51–147 MPa) but lower elasticity (Elastic Modulus = 2136–10,079 MPa) than other samples more homogeneous in nature (0.5% alginate, Elastic Modulus = 1918 MPa). Beads with 0.5% alginate prevented the degradation of β-carotene 1.5 times more efficiently than 1% beads (5% CaCl2) at any of the storage temperatures studied. Therefore, it was postulated that calcium alginate networks crosslinked to a greater extent and in a more homogeneous manner showed better mechanical performance and barrier properties for encapsulation applications

Quality and acceptability of microwave and conventionally pasteurized kiwifruit puree

The final publication is available at link.springer.com[EN] The development and optimisation of food preservation processes seem to be necessary in order to address consumer expectations related to secure, fresh-like foods. To this end, the sensory, nutritional and functional properties must be maximally retained. In order to contribute to the acquisition of knowledge about the adequacy of microwave processing as a means of preserving fruit-based products, the present study compares the impact of microwave heating with conventional thermal processing. The consumer acceptance of fresh and pasteurised kiwifruit puree was studied as was the content of water, soluble solids and bioactive compounds and the pH, consistency, viscosity, colour coordinates and antioxidant capacity, as well as the effect of the thermal treatment on enzyme and microbial inactivation. As bioactive compounds, the content of vitamins C, A and E and the total flavonoid, phenol and tannin content have been considered. As the obtained results show, not only was microwaved puree preferred by consumers, but it also exhibited a superior maintenance of the nutritive and functional properties of the fruit, smaller colour changes and a content of inactivated enzymes and microorganisms equal to or greater than the conventionally heated sample.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Project AGL 2010-22176 and AGL 2010-22206-C02-01 and the grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Igual Ramo, M.; Salvador Alcaraz, A.; Rodrigo Aliaga, MD.; Martínez Navarrete, N. (2014). Quality and acceptability of microwave and conventionally pasteurized kiwifruit puree. Food and Bioprocess Technology. 7(11):3282-3292. https://doi.org/10.1007/s11947-014-1315-9S32823292711Awuah, G. B., Ramaswamy, H. 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Effects of microwave heating on sensory characteristics of kiwifruit puree. Food and Bioprocess Technology, 5, 3021–3031.Benlloch-Tinoco, M., Igual, M., Rodrigo, D., & Martínez-Navarrete. (2013). Comparison of microwaves and conventional thermal treatment on enzymes activity and antioxidant capacity of kiwifruit puree. Innovative Food Science and Emerging Technologies, 19, 166–172.Benlloch-Tinoco, M., Martínez-Navarrete, N., & Rodrigo, D. (2014). Impact of temperature on lethality of kiwifruit puree pasteurization by thermal and microwave processing. Food Control, 35, 22–25.Bodart, M., de Peñaranda, R., Deneyer, A., & Flamant, G. (2008). Photometry and colorimetry characterisation of materials in daylighting evaluation tools. Building and Environment, 43, 2046–2058.Contreras, C., Martín-Esparza, M. E., Martínez-Navarrete, N., & Chiralt, A. (2007). Influence of osmotic pre-treatment and microwave application on properties of air dried strawberry related to structural changes. 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E., & Martínez-Navarrete, N. (2012). Assessment of the bioactive compounds, color, and mechanical properties of apricots as affected by drying treatment. Food and Bioprocess Technology, 6, 3247–3255.Gerard, K. A., & Roberts, J. S. (2004). Microwave heating of apple mash to improve juice yield and quality. LWT--Food Science and Technology, 37, 551–557.Guan, D., Plotka, V. C. F., Clark, S., & Tang, J. (2002). Sensory evaluation of microwave treated macaroni and cheese. Journal of Food Processing and Preservation, 26, 307–322.Huang, Y., Sheng, J., Yang, F., & Hu, Q. (2007). Effect of enzyme inactivation by microwave and oven heating on preservation quality of green tea. Journal of Food Engineering, 78, 687–692.Igual, M., García-Martínez, E., Camacho, M. M., & Martínez-Navarrete, N. (2010). Effect of thermal treatment and storage on the stability of organic acids and the functional value of grapefruit juice. Food Chemistry, 118(2), 291–299.Igual, M., García-Martínez, E., Camacho, M. d. 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Superiority of microwaves over conventional heating to preserve shelf-life and quality of kiwifruit puree

[EN] The effect of both microwave (1000 W-340 s) and conventional heating (97 degrees C-30 s) on the quality and shelf-life of kiwifruit puree was investigated. The growth of microorganisms and the evolution of enzyme activity, colour, pH, bioactive compounds and antioxidant activity in the product during storage at 4, 10 and 22 degrees C were checked. The storage temperature had a significant (p < 0.05) impact on both the shelf-life and the nutritional and functional value of the samples: the higher the temperature, the significantly (p <0.05) faster the rate of both the sample spoilage and the loss of the bioactive compounds. On the other hand, thermal processing significantly (p < 0.05) reduced the growth of microorganisms and the degradation rate of some bioactive compounds in a 12-59%, as well as leading to enzyme and colour stabilization. A longer shelf-life (123 days at 4 degrees C) and a superior preservation of colour (Delta E-SE = 6.54) and bioactive compounds (57-67%) were obtained when microwave heating was the technology selected to process the kiwifruit puree. Microwave heating was considered a suitable means of preserving kiwifruit puree that might be successfully employed as an innovation tool with which to help safe, high-quality and minimally processed kiwifruit based-products reach the market.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Projects AGL 2010-22176 and AGL 2010-22206-C02-01 and the Generalitat Valenciana for the Grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Igual Ramo, M.; Rodrigo Aliaga, MD.; Martínez Navarrete, N. (2015). Superiority of microwaves over conventional heating to preserve shelf-life and quality of kiwifruit puree. Food Control. 50:620-629. https://doi.org/10.1016/j.foodcont.2014.10.006S6206295

Impact of temperature on lethality of kiwifruit puree pasteurization by thermal and microwave processing

The use of pasteurization units (PU) as a measure of the lethal effect of processes was proposed with the aim of comparing conventional and novel thermal technologies. Kiwifruit puree was subjected to microwave (1000 and 900 W) and conventional (97 C) heating. Processing conditions of the treatments were chosen to simulate a pasteurization treatment. The temperature profiles of the samples during processing were recorded at different positions. The coldest and hottest spots of the product were identified and the associated PU numbers were calculated. A significantly (p < 0.05) higher thermal load was necessary in order to stabilize the kiwifruit puree under conventional (19.27 min) than microwave heating mode (0.003e8 min) at any of the conditions studied. The higher effectiveness of microwave heating could be attributed to non-thermal effects associated with this technology.The authors thank the Ministerio de Educacion y Ciencia for the financial support given through Projects AGL 2010-22176 and AGL 2010-22206-C02-01 and the grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Martínez Navarrete, N.; Rodrigo Aliaga, MD. (2014). Impact of temperature on lethality of kiwifruit puree pasteurization by thermal and microwave processing. Food Control. 35(1):22-25. https://doi.org/10.1016/j.foodcont.2013.06.035S222535

Comparison of microwaves and conventional thermal treatment on enzymes activity and antioxidant capacity of kiwifruit puree

Enzymes are naturally present in food and can cause product deterioration. For this reason,most food-processing steps try to reduce the enzymatic activity. The aimof thisworkwas to compare, in terms of both the inactivation of kiwifruit puree peroxidase, polyphenoloxidase and pectinmethylesterase and also themaintenance of the antioxidant capacity of the product, the effect of a microwave treatment with a conventional thermal treatment designed to cause the same level of peroxidase inactivation (90%). The microwave power and process time that best permitted the maximisation of both the enzyme inactivation and the antioxidant capacity of the product, were selected by means of the Response Surface Methodology. The results obtained point to microwave heating as an appropriate technology with which to produce a stable kiwifruit puree, since these treatments were more effective at enzyme inactivation and antioxidant capacity retention than the conventional thermal treatment.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Project AGL 2010-22176 and the Generalitat Valenciana for the financial support given throughout Project ACOMP/2012/161 and the Grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Igual Ramo, M.; Rodrigo Aliaga, MD.; Martínez Navarrete, N. (2013). Comparison of microwaves and conventional thermal treatment on enzymes activity and antioxidant capacity of kiwifruit puree. Innovative Food Science and Emerging Technologies. 19:166-172. https://doi.org/10.1016/j.ifset.2013.05.007S1661721

Listeria Monocytogenes inactivation kinetics under microwave and conventional thermal processing in a kiwifruit puree

The inactivation of Listeria monocytogenes in a kiwifruit puree by conventional and microwave heating was studied. Survival curves at three microwave power levels (600 1000 W) and three temperatures (50 60 °C) were obtained. Data were properly fitted by a first-order kinetic model. Processing times under both technologies were corrected to isothermal treatment for the kinetic study. Microwave heating was shown to effectively inactivate L. monocytogenes. In the range of microwave and conventional processing conditions assayed, the 5-log10 reductions of L. monocytogenes recommended by the FDA for pasteurized products were achieved. The level of microwave power applied had a considerable influence on the Listeria monocytogenes inactivation rate. The higher the power level, the faster the inactivation. The inactivation of Listeria monocytogenes under microwave heating at 900 W (D60°C=17.35 s) and 1000 W (D60°C=17.04 s) happened faster than in a conventional thermal process (D60°C=37.45 s). Consequently, microwave heating showed greater effectiveness for Listeria monocytogenes inactivation than conventional heating.The authors thank the Ministerio de Educacion y Ciencia for the financial support given through Projects AGL 2010-22176 and AGL 2010-22206-C02-01 and the Generalitat Valenciana for the financial support given through Project ACOMP/2012/161 and the Grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Pina Pérez, MC.; Martínez Navarrete, N.; Rodrigo Aliaga, MD. (2014). Listeria Monocytogenes inactivation kinetics under microwave and conventional thermal processing in a kiwifruit puree. Innovative Food Science and Emerging Technologies. 22:131-136. https://doi.org/10.1016/j.ifset.2014.01.005S1311362

Effects of Microwave Heating on Sensory Characteristics of Kiwifruit Puree

The effect of microwave processing on the characteristics of kiwifruit puree was evaluated by applying various gentle treatments. Different combinations of microwave power/processing time were applied, with power among 200-1,000 W and time among 60-340 s, and various sensory and instrumental measurements were performed with the aim of establishing correlations and determining which instrumental parameters were the most appropriate to control the quality of kiwi puree. The water and soluble solids of the product, 83 and 14/100 g sample, respectively, did not change due to treatments. For sensory assessment, an expert panel was previously trained to describe the product. Fourteen descriptors were defined, but only the descriptors 'typical kiwifruit colour', 'tone', 'lightness', 'visual consistency' and 'typical taste' were significant to distinguish between kiwifruit puree samples. The instrumental analysis of samples consisted in measuring consistency, viscosity, colour and physicochemical characteristics of the treated and fresh puree. Applying intense treatments (600 W-340 s, 900 W-300 s and 1,000 W-200 s) through high power or long treatment periods or a combination of these factors, mainly affects the consistency (flow distance decreased from 5. 9 to 3. 4 mm/g sample), viscosity (increased from 1. 6 to 2. 5 Pa/s), colour (maximun ¿E was 6 U) and taste of the product. As a result, samples were thicker and with an atypical flavour and kiwifruit colour due to increased clarity (L* increased from 38 to 43) and slight changes in the yellow-green hue (h* decreased from 95 to 94). For the instrumental determinations of colour and visual perception of consistency, the most suitable parameters for quality control are the colour coordinates L*, a*, h*, whiteness index and flow distance measured with a Bostwick consistometer. © 2011 Springer Science+Business Media, LLC.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Project AGL 2010-22176. The authors are indebted to the Generalitat Valenciana (Valencia, Spain) for the Grant awarded to the author Maria Benlloch. The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain.Benlloch Tinoco, M.; Varela Tomasco, PA.; Salvador Alcaraz, A.; Martínez Navarrete, N. (2012). Effects of Microwave Heating on Sensory Characteristics of Kiwifruit Puree. Food and Bioprocess Technology. 5(8):3021-3031. https://doi.org/10.1007/s11947-011-0652-1S3021303158Albert, A., Varela, P., Salvador, A., & Fiszman, S. M. (2009). 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ESTUDIO COMPARATIVO DE LA CALIDAD Y SEGURIDAD DE UN PURÉ DE KIWI PASTEURIZADO POR CALENTAMIENTO CONVENCIONAL O POR MICROONDAS

Tesis por compendio[EN] In the present Doctoral Thesis, the suitability of the use of microwave energy as an alternative to conventional heating to safely pasteurise and efficiently preserve the quality of a kiwifruit puree was investigated. To this end, the impact of microwave heating on the enzymatic activity, microorganisms, pathogenic or spoilage, physicochemical, sensory, nutritional and functional properties of the product was studied, following the processing step and during successive storage. On this basis, a pasteurisation microwave treatment was designed and validated, and effectiveness of microwave technology and conventional heating to preserve the safety and quality of the product were compared based on several criteria. Although microwave processing led to a non-uniform heating of the kiwifruit puree, with the coldest and the hottest spots being located at its central region and its edges, respectively, this technology allowed an effective inactivation of enzymes and microorganisms (pathogenic or spoilage) without severely affecting the quality of the product. On the basis of the data provided by the inactivation kinetics of L. monocytogenes under microwave heating, along with the outputs of an experimental design, which was used to study the effect of microwave power and process time on the enzymatic inactivation and the functional properties of the product, the best processing conditions were chosen. These treatment conditions permitted to reach the target level of microbial inactivation as well as minimise the enzymatic activity and maximise the preservation of the functional value of the product were selected. The optimum microwave treatment was found to cause a 90% of peroxidase inactivation and reduce more than 5-log10 cycles of L. monocytogenes, with a 99.9% of probability. An equivalent conventional pasteurisation treatment was designed with comparative purposes. From the comparison established, superiority of microwaves over conventional heating to inactivate enzymes and microorganisms was pointed out, given that, on the one hand, lower thermal load (lower value of pasteurisation units) was needed in order to achieve the same level of peroxidase inactivation and, on the other hand, a shorter decimal reduction time (lower D-value) of L. monocytogenes was obtained when the kiwifruit puree was processed by means of microwave technology. Accordingly, although microwave pasteurisation led to an analogous inactivation of L. monocytogenes and similarly affected the consistency and carotenoids content of the puree, this treatment gave rise to a superior preservation of the bioactive compounds and antioxidant activity, as well as, the chlorophylls content of the product. Additionally, the microwave pasteurised kiwifruit puree showed a colour more similar to that of the fresh fruit, a greater sensory acceptability, a longer shelf-life (123 days at 4 ºC) and greater stability during storage. In conclusion, more than conventional heating, microwave technology was found to be an appropriate means of processing a kiwifruit puree, as well as any other fruit puree with similar characteristics, so as to obtain high-quality and safe pasteurised fruit-based products.[ES] En la presente Tesis se evalúa la idoneidad del uso de las microondas como tecnología alternativa a la pasteurización convencional, para preservar un puré de kiwi desde el punto de vista de la seguridad y la calidad del mismo. Para ello, se ha estudiado el impacto de esta tecnología sobre diversas enzimas, microorganismos patógenos y alterantes y distintas propiedades fisicoquímicas, sensoriales, nutricionales y funcionales del puré, tras el procesado y durante el almacenamiento. Se ha establecido y validado un tratamiento de pasteurización por microondas y se ha comparado la efectividad de esta tecnología frente al calentamiento convencional a la hora de conservar el producto en base a diversos criterios. Aunque la energía microondas dio lugar a un calentamiento heterogéneo del puré, detectándose el punto más frío en la zona central del producto y el punto más caliente en la zona superior de sus laterales, éste resultó efectivo frente a la inactivación tanto de enzimas como de microorganismos patógenos y alterantes, sin causar un excesivo deterioro de su calidad. Se obtuvieron diversos modelos cinéticos que permitieron predecir la inactivación microbiológica del puré de kiwi durante el calentamiento por microondas. Se empleó un diseño de experimentos para determinar las condiciones de proceso más adecuadas para pasteurizar el producto mediante esta tecnología, en base a la inactivación enzimática y al deterioro de sus propiedades funcionales. El tratamiento por microondas seleccionado dio lugar a un puré de kiwi tanto estable (90% de inactivación de la enzima peroxidasa) como inocuo (> 5 reducciones logarítmicas de L. monocytogenes) a un 99,9% de probabilidad. Asimismo, se estableció un tratamiento de pasteurización convencional equivalente con fines comparativos. A raíz de la comparación establecida, quedó patente la superioridad de las microondas para inactivar tanto enzimas como microorganismos, ya que, por un lado, se requirió de una menor carga térmica (menos unidades de pasteurización) para alcanzar un nivel equivalente de inactivación de peroxidasa y, por el otro, el tiempo de reducción decimal (valor de D) del microorganismo patógeno estudiado L. monocytogenes resultó ser menor, cuando el puré de kiwi se procesó mediante la aplicación de microondas que cuando éste se sometió al calentamiento convencional. En consecuencia, la pasteurización por microondas, aunque causó un nivel de inactivación de L. monocytogenes semejante y afectó de forma similar a la consistencia y al contenido en carotenoides del mismo que el tratamiento térmico convencional, permitió alcanzar una mayor inactivación de la flora alterante del producto, así como, de las enzimas polifenoloxidasa y pectinmetilesterasa. Además, el tratamiento de pasteurización por microondas preservó en mayor medida el contenido en compuestos bioactivos, la actividad antioxidante y el contenido en clorofilas del producto, dando lugar a un puré de kiwi con un color más semejante al propio de la fruta fresca, que presentó además, una mayor aceptabilidad sensorial, una vida útil más larga (123 días a 4 ºC) y una mayor estabilidad de sus propiedades durante el almacenamiento. En base a todo lo anterior, se recomienda la aplicación de la tecnología microondas como una alternativa interesante al procesado térmico convencional a la hora de pasteurizar un puré de kiwi, así como de otras frutas de características similares, con el fin de obtener productos procesados a base de fruta de mayor calidad sin que la innocuidad de los mismos se vea comprometida.[CA] En la present Tesi s'avalua la idoneïtat de l'ús de les microones com a tecnologia alternativa a la pasteurització convencional, per a preservar un puré de kiwi des del punt de vista de la seguretat i la qualitat del mateix. Per a això, s'ha estudiat l'impacte d'esta tecnologia sobre diversos enzims, microorganismes patògens i alterants i distintes propietats fisicoquímiques, sensorials, nutricionals i funcionals del puré, després del processat i durant l'emmagatzemament. S'ha establit i validat un tractament de pasteurització per microones i s'ha comparat l'efectivitat d'esta tecnologia enfront del calfament convencional a l'hora de conservar el producte basant-se en diversos criteris. Encara que l'energia microones va donar lloc a un calfament heterogeni del puré, detectant-se el punt més fred en la zona central del producte i el punt més calent en la zona superior dels seus laterals, aquest va resultar efectiu per a inactivar tant enzims com microorganismes patògens i alterants, sense causar un excessiu deteriorament de la seua qualitat. Es van obtindre diversos models cinètics que van permetre predir la inactivació microbiològica del puré de kiwi durant el calfament per microones i es va utilitzar un disseny d'experiments per a determinar les condicions de procés més adequades per a pasteuritzar el producte per mitjà d'esta tecnologia, basant-se en la inactivació enzimàtica i el deteriorament de les seues propietats funcionals. El tractament per microones seleccionat va donar lloc a un puré de kiwi tant estable (90% d'inactivació de l'enzim peroxidasa) com innocu (> 5 reduccions logarítmiques de L. monocytogenes) a un 99,9% de probabilitat. Així mateix, es va establir un tractament de pasteurització convencional equivalent amb fins comparatius. Arran de la comparació establida, va quedar patent la superioritat de les microones per a inactivar tant enzims com microorganismes, ja que, d'una banda, es va requerir d'una menor càrrega tèrmica (menys unitats de pasteurització) per a aconseguir un nivell equivalent d'inactivació de peroxidasa i, per l'altre, el temps de reducció decimal (valor de D) del microorganisme patogen L. monocytogenes va resultar ser menor, quan el puré de kiwi es va processar per mitjà de l'aplicació de microones que quan este es va sotmetre al calfament convencional. En conseqüència, la pasteurització per microones, encara que va causar un nivell d'inactivació de L. monocytogenes semblant i va afectar de forma anàloga a la consistència i al contingut en carotenoides del mateix que el tractament tèrmic convencional, va permetre aconseguir una major inactivació de la flora alterant del producte, així com, dels enzims polifenoloxidasa i pectinmetilesterasa. A més, el tractament de pasteurització per microones va preservar en major grau el contingut en compostos bioactius i activitat antioxidant i el contingut en clorofil·les del producte, donant lloc a un puré de kiwi amb un color més semblant al propi de la fruita fresca, que va presentar a més, una major acceptabilitat sensorial, una vida útil més llarga (123 dies a 4 ºC) i una major estabilitat de les seues propietats durant l'emmagatzemament. Basant-se en tot l'anterior, es recomana l'aplicació de la tecnologia microones com una alternativa interessant al processat tèrmic convencional a l'hora de pasteuritzar un puré de kiwi, així com d'altres fruites de característiques semblants, a fi d'obtindre productes processats a base de fruita de major qualitat sense que la innocuïtat dels mateixos es veja compromesa.Benlloch Tinoco, M. (2015). ESTUDIO COMPARATIVO DE LA CALIDAD Y SEGURIDAD DE UN PURÉ DE KIWI PASTEURIZADO POR CALENTAMIENTO CONVENCIONAL O POR MICROONDAS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53708TESISPremios Extraordinarios de tesis doctoralesCompendi

Impact of temperature on lethality of kiwifruit puree pasteurization by thermal and microwave processing

a b s t r a c t The use of pasteurization units (PU) as a measure of the lethal effect of processes was proposed with the aim of comparing conventional and novel thermal technologies. Kiwifruit puree was subjected to microwave (1000 and 900 W) and conventional (97 C) heating. Processing conditions of the treatments were chosen to simulate a pasteurization treatment. The temperature profiles of the samples during processing were recorded at different positions. The coldest and hottest spots of the product were identified and the associated PU numbers were calculated. A significantly (p &lt; 0.05) higher thermal load was necessary in order to stabilize the kiwifruit puree under conventional (19.27 min) than microwave heating mode (0.003e8 min) at any of the conditions studied. The higher effectiveness of microwave heating could be attributed to non-thermal effects associated with this technology