The health properties of fruit are widely known. Powdered fruit may be a practical format to be offered to the consumer. Nevertheless, the process used to obtain the powder must ensure the maximum retention of the bioactive compounds and the functional value of the fruit while retaining adequate physical properties. The aim of this study was to compare freeze-drying and spray drying as the drying technologies to obtain grapefruit powder. The obtained results allow freeze-drying to be proposed as a better technology than spray drying in order to obtain a product with a higher content of vitamin C and total carotenoids. Moreover, all of the edible part of the fruit is used in this case, so a greater quantity of healthy compounds is preserved and by-product generation is avoided. Adding about 6 g water, 4 g Arabic gum and 0.6 g bamboo fibre/100 g grapefruit pulp is recommended before freeze-drying.

Grapefruit is a fruit with interesting nutritional value and functional properties, but a short life. Freeze-drying (FD) is a valuable technique as it produces high-quality dehydrated products. This study is aimed to obtain new food ingredients based on freeze-dried grapefruit formulated with high molecular weight solutes (gum arabic and bamboo fiber) in three different proportions (F1, F2, and F3). To improve the FD, a mild microwave drying pre-treatment was applied. Influence of the water content and the presence of high molecular weight solutes on freeze-drying kinetics was tested by Midilli-Kucuk and Page models. The best FD kinetic model fit on grapefruit powders were Midilli-Kucuk for F2 and F3, and Page for F1, and the adequate freeze-drying times for F1, F2, and F3 were 24, 16, and 18 h, respectively. Final samples were evaluated for nutritional and antioxidant capacity. Gum arabic and bamboo fiber present a protector effect, which results in a significant antioxidant capacity due to the protection of flavonoids and antioxidant vitamins. These novel food ingredients could be of great interest for the food industry in order to develop foods with improved antioxidant capacity as well as enriched in natural fibers and/or micronutrients.

a b s t r a c tDifferent grapefruit powders obtained by freeze drying and spray drying with prior addition of shell materials (arabic gum and bamboo fiber) were studied in order to evaluate the effect of these preservation processes on the retention of antioxidants, in comparison with the freeze-dried fruit with no carriers added. Freeze-dried samples showed above 90% retention of these phytochemicals, while spraydried samples presented good retention of vitamins but a sharp decrease in of phenolic compounds. Pearson's correlation analysis showed that the most significant contribution to DPPH scavenging activity and inhibition of b-carotene bleaching was provided by phenolic compounds, mostly flavonoids, while the contribution to the reducing power was due to ascorbic acid and a-tocopherol. Therefore, the loss of these compounds in the spray-dried samples resulted in products with lower antioxidant activity. Naringin and narirutin were the major phenolic compounds in all grapefruit samples, although other flavanones present in lower concentration, like hesperidin, neohesperidin didymin, poncirin or melitidin, also showed high correlations with the antioxidant value of the samples.

ElsevierAgudelo Sterling, CM.; Igual Ramo, M.; Talens Oliag, P.; Martínez Navarrete, N. (2015). Optical and mechanical properties of cocona chips as affected by the drying process. AbstractThe effect of the application of a pre-osmotic treatment to obtain hot air dried cocona (Solanum sessiliofurum Dunal) chips was studied. The drying kinetics and the optical and mechanical properties of cocona chips obtained by the combined method of osmotic dehydration and hot air drying (OD+HAD) and by only hot air drying (HAD) were compared. Samples were dried by hot air at 60ºC. For the combined method, they were pre-dried to a moisture content of 75 g water /100g, immersed in a 55 ºBrix sucrose solution at 25ºC for 48 minutes. The pre-osmodehydration applied did not influence the subsequent hot air drying kinetics, resulting in a final product with 0.055 ± 0.005 g water /g cocona. The optical properties of OD+HAD chips were more favourable, exhibiting a smaller color change with respect to the fresh fruit (±15 units) than the HAD samples (±23 units). On the other hand, the OD+HAD chips presented more fracture peaks than HAD ones, this related with a structure with a higher degree of crispness, a very desirable property for a chip product.

The configuration of the sensory quality of coffee begins in the tree, where chemical precursors are deposited and formed in the seeds as the fruits develop. Fruit within the range classified as mature can have a wide range of properties. This study evaluated three degrees of maturity and established their chemical and sensory characteristics using analytical techniques such as liquid and gas chromatography. The maturity states evaluated did not show differences in organic acids, free fatty acids, lipids, total chlorogenic acids, proteins, alkaloids or sucrose. Fructose and glucose showed differences with respect to the degree of maturity, with higher values associated with more developed states. The analysis of variance did not show a significant effect on sensory attributes or sensory quality. The chromatic coordinate a* of the CIEL*a*b* scale reached a maximum value of 25.16, and the evaluated states were different from each other.

Rehydrating the freeze-dried or spray-dried powder to the level of the natural juice, instead of that of the crushed or liquidized grapefruit, and incorporating sugar at this stage would probably improve the quality of the samples. © 2018 Society of Chemical Industry.

El café natural (CN) se destaca por sus descriptores sensoriales diferenciales en los atributos de fragancia/aroma y sabor con respecto a los cafés lavados. Dentro de los procedimientos para su obtención, el secado constituye un factor crítico para el aseguramiento de su calidad. Con el objetivo de evaluar el efecto del secado en la calidad del CN se evaluaron cinco modalidades, consistentes en un secado inicial al sol (S), complementado con secado mecánico (M): S45%+M, S50%+M, S55%+M, S100%, M100% y el testigo, café lavado 100% secado mecánicamente (LM). El CN en los diferentes tratamientos alcanzó una humedad del 10%-12%, entre 9 y 17 días; comportamiento que se describió a partir de una función de tipo logarítmico y un R2>0,92. Para el LM, el café requirió un promedio de 4 días de secado, explicada a través de un polinomio de tercer grado R2 de 0,999. El CN se destacó por presentar un contenido adecuado de actividad del agua. Respecto a las variables físicas del grano, la merma en promedio fue del 50,7% y la almendra sana de 42,6%, con valores de almendra defectuosa entre 2,6% y 6,6%. Con relación a la calidad sensorial, el puntaje total promedio SCA (Specialty Coffee Association) para el LM fue de 82,9 y para el CN de 83,9; con descriptores destacables en fragancia/aroma de chocolate, frutal, caramelo y miel, notas de pulpa dulce y vino. Los resultados llevan a concluir que un proceso adecuado de secado permite obtener CN con destacada calidad física y sensorial.

La técnica de espectroscopia de infrarrojo cercano-NIRS se ha consolidado como una técnica analítica secundaria confiable, objetiva, reproducible, verificable, económica y de bajo impacto ambiental. Esta investigación tuvo como objetivo realizar la validación de la ecuación desarrollada a partir de la técnica NIRS para café verde almendra, que predice actualmente 13 compuestos químicos (cafeína, trigonelina, ácidos clorogénicos totales, lípidos totales, ácidos grasos (palmítico, esteárico, oleico, linoleico, linolénico y araquídico), isómeros (3-CQA, 4-CQA y 5-CQA) y sacarosa. La validación se realizó con 70 muestras de café verde arábigo (Coffea arabica L.), variedades Castillo®, Cenicafé 1 y Tabi, producidas en los departamentos de Cauca, Cesar y Caldas, analizadas para la determinación de los compuestos químicos por métodos analíticos internacionales de la AOAC y estandarizados en Cenicafé; simultáneamente las muestras fueron analizadas en el equipo NIRS. A partir de los análisis estadísticos descriptivos, análisis de concordancia de Blan Altman y de correlación de Pearson entre el sesgo y magnitud, pudo establecerse la concordancia entre los métodos analíticos internacionales y el NIRS. El error relativo obtenido por la técnica NIRS para los compuestos cafeína, sacarosa, ácidos clorogénicos totales, isómeros de ácidos clorogénicos 4-CQA y 5-CQA, lípidos totales, ácidos grasos araquídico, esteárico y palmítico fue inferior al 6,0%. Los compuestos trigonelina y el ácido linoleico presentaron un error del 7,0% y el ácido oleico del 10,0%. Los resultados que soportan la investigación confirman que, con la calibración de la curva, la técnica NIRS puede constituirse como un método analítico secundario.