Critical water activity and critical water content of freeze-dried strawberry powder as affected by maltodextrin and arabic gum

The adsorption isotherms (20 °C) and the relationship between water content and glass transition temperature were modeled in freeze-dried strawberry powder studying the effect of the addition of maltodextrin and arabic gum. Both compositional and physicochemical analyses of strawberry pulp were performed. If the midpoint of the glass transition is considered, the critical water activity that ensures the glassy state of the product during storage at 20 °C increased from 0.094 to 0.237-0.341 when maltodextrin and arabic gum were added, respectively. The increase in the critical water content was not so marked and it was noticeable only in arabic gum added sample (from 7.5 to 8.9. g water/100. g product), being this sample more stable. © 2011 Elsevier Ltd.Mosquera, LH.; Moraga Ballesteros, G.; Martínez Navarrete, N. (2012). Critical water activity and critical water content of freeze-dried strawberry powder as affected by maltodextrin and arabic gum. Food Research International. 47(2):201-2016. doi:10.1016/j.foodres.2011.05.019S201201647

Stability of the physical properties, bioactive compounds and antioxidant capacity of spray-dried grapefruit powder

[EN] Spray-drying may be an interesting alternative means of offering consumers high quality, stable, and easy-tohandle fruit. The stability of grapefruit powder formulated with gum Arabic, maltodextrin and whey protein isolate was studied. The changes during powder storage at 20 degrees C of the vitamin C (VC), total phenolics (TP), lycopene (Lp), antioxidant activity (AOA), color and mechanical properties were studied at different relative humidities (RH), from 0 to 56% for up to 9 month, either exposed to light or in darkness. Results showed that TP were the most stable compounds and Lp the most unstable. The properties studied with grapefruit powder were relatively stable when stored at 20 degrees C, in darkness or light, at RH <= 23.1% and for no more than 6 months. With these conditions, losses of 32, 3, 23-68 and 90% were observed for TP, VC, AOA and Lp, respectively, and the powder maintained its flowability and color.The authors wish to thank Ministerio de Economia y Competitividad and Fondo Europeo de Desarrollo Regional for the financial support given through the Project AGL 2012-39103.González, F.; García Martínez, EM.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2019). Stability of the physical properties, bioactive compounds and antioxidant capacity of spray-dried grapefruit powder. Food Bioscience. 28:74-82. https://doi.org/10.1016/j.fbio.2019.01.009S74822

Effect of storage temperature on the crispness, colour and bioactive compounds of an orange snack obtained by freeze-drying

[EN] Purpose A healthy and easy-to-use orange snack obtained from the freeze-dried orange pulp puree is proposed. Once the commercial packaging of the snack has been opened, the effect of conventional home storage temperature on its physicochemical properties and on the content of bioactive compounds has been studied. This research aims to recommend the consumer, and therefore the manufacturer, the best conditions for home storage of this product, keeping its nutritional quality and antioxidant capacity, as well as maintaining its colour and crispness. Design/methodology/approach The water content, water activity, hygroscopicity, crispness, colour, vitamin C, beta-carotene, total phenolic compounds and antioxidant activity were characterised both when the orange snack was newly obtained and after one, two and six months of storage inside zipper bags, at 4 and 20 oC. Findings The results indicated that, in these conditions, the orange snack increased its water content, causing a loss in both its porosity and its characteristic crispness. Nevertheless, the bioactive compounds remained stable throughout the storage period, with the exception of beta-carotene, the content of which decreased markedly when the orange snack was stored at 20 oC. Originality/value Few studies have evaluated the stability of food products during home storage. The findings showed that the maximum storage time to ensure a proper texture of the orange snack studied is between two and six months, both at 4 and 20 oC. However, from the point of view of the conservation of both vitamin C and, especially, of beta-carotene, it is recommended that this product be stored in refrigeration.The authors thank the Ministerio de Economia, Industria y Competitividad of Spain for the financial support given through the Project AGL 2017-89251-R (AEI/FEDER-UE) and the Ministerio de Universidades for the FPU grant (FPU14 / 02633) awarded to Ms. Andrea Silva.Silva Espinoza, MA.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2021). Effect of storage temperature on the crispness, colour and bioactive compounds of an orange snack obtained by freeze-drying. British Food Journal. 123(6):2095-2106. https://doi.org/10.1108/BFJ-11-2020-1061S20952106123

Use of different biopolymers as carriers for purposes of obtaining a freeze-dried orange snack

[EN] In addition to colour, one of the most important qualifies of a snack-type product is its crunchy texture. A freeze-dried fruit snack is characterised by its low water content, which creates the problem of a loss of crunchiness related to its low glass transition temperature (Tg). In this sense, a common technique with which to increase the Tg of these types of products is to add different biopolymers. However, these compounds can, at the same time, affect the colour and texture of the product. In this study, different biopolymers have been tested in order to discover their similarities or differences in terms of hygroscopicity, antiplasticising character, colour and impact on the mechanical properties of a freeze-dried orange snack formulated from their different mixtures. Gum Arabic, maltodextrin, starch modified with octenylsuccinic anhydride, pea fibre, bamboo fibre and native corn starch have been selected as biopolymers. The impact of any of them on the studied properties can be confirmed, without any of them being more or less effective than the others.The authors thank the Ministerio de Economia y Competitividad for the financial support given through the Project AGL 2017-89251-R (AEI/FEDER-UE) and the Ministerio de Educacion for the FPU grant (FPU14/02633) awarded to Ms. Andrea Silva.Silva Espinoza, MA.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2020). Use of different biopolymers as carriers for purposes of obtaining a freeze-dried orange snack. LWT - Food Science and Technology. 127:1-7. https://doi.org/10.1016/j.lwt.2020.109415S17127Acevedo, N. C., Schebor, C., & Buera, P. (2008). Non-enzymatic browning kinetics analysed through water–solids interactions and water mobility in dehydrated potato. Food Chemistry, 108(3), 900-906. doi:10.1016/j.foodchem.2007.11.057Agudelo, C., Igual, M., Camacho, M., & Martínez-Navarrete, N. (2016). Effect of process technology on the nutritional, functional, and physical quality of grapefruit powder. Food Science and Technology International, 23(1), 61-74. doi:10.1177/1082013216658368Bhusari, S. N., Muzaffar, K., & Kumar, P. (2014). Effect of carrier agents on physical and microstructural properties of spray dried tamarind pulp powder. Powder Technology, 266, 354-364. doi:10.1016/j.powtec.2014.06.038Brunauer, S., Deming, L. S., Deming, W. E., & Teller, E. (1940). On a Theory of the van der Waals Adsorption of Gases. Journal of the American Chemical Society, 62(7), 1723-1732. doi:10.1021/ja01864a025Brunauer, S., Emmett, P. H., & Teller, E. (1938). Adsorption of Gases in Multimolecular Layers. Journal of the American Chemical Society, 60(2), 309-319. doi:10.1021/ja01269a023Cano-Chauca, M., Stringheta, P. C., Ramos, A. M., & Cal-Vidal, J. (2005). Effect of the carriers on the microstructure of mango powder obtained by spray drying and its functional characterization. Innovative Food Science & Emerging Technologies, 6(4), 420-428. doi:10.1016/j.ifset.2005.05.003Chang, Y. P., Cheah, P. B., & Seow, C. C. (2000). Plasticizing—Antiplasticizing Effects of Water on Physical Properties of Tapioca Starch Films in the Glassy State. Journal of Food Science, 65(3), 445-451. doi:10.1111/j.1365-2621.2000.tb16025.xChoudhury, D., Sahu, J. K., & Sharma, G. D. (2011). Moisture sorption isotherms, heat of sorption and properties of sorbed water of raw bamboo (Dendrocalamus longispathus) shoots. Industrial Crops and Products, 33(1), 211-216. doi:10.1016/j.indcrop.2010.10.014Da Silva, F. C., da Fonseca, C. R., de Alencar, S. M., Thomazini, M., Balieiro, J. C. de C., Pittia, P., & Favaro-Trindade, C. S. (2013). Assessment of production efficiency, physicochemical properties and storage stability of spray-dried propolis, a natural food additive, using gum Arabic and OSA starch-based carrier systems. Food and Bioproducts Processing, 91(1), 28-36. doi:10.1016/j.fbp.2012.08.006Fabra, M. J., Talens, P., Moraga, G., & Martínez-Navarrete, N. (2009). Sorption isotherm and state diagram of grapefruit as a tool to improve product processing and stability. Journal of Food Engineering, 93(1), 52-58. doi:10.1016/j.jfoodeng.2008.12.029Fongin, S., Kawai, K., Harnkarnsujarit, N., & Hagura, Y. (2017). Effects of water and maltodextrin on the glass transition temperature of freeze-dried mango pulp and an empirical model to predict plasticizing effect of water on dried fruits. Journal of Food Engineering, 210, 91-97. doi:10.1016/j.jfoodeng.2017.04.025Goula, A. M., Karapantsios, T. D., Achilias, D. S., & Adamopoulos, K. G. (2008). Water sorption isotherms and glass transition temperature of spray dried tomato pulp. Journal of Food Engineering, 85(1), 73-83. doi:10.1016/j.jfoodeng.2007.07.015Greenspan, L. (1977). Humidity fixed points of binary saturated aqueous solutions. Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 81A(1), 89. doi:10.6028/jres.081a.011Martínez-Navarrete, N., Salvador, A., Oliva, C., & Camacho, M. M. (2019). Influence of biopolymers and freeze-drying shelf temperature on the quality of a mandarin snack. LWT, 99, 57-61. doi:10.1016/j.lwt.2018.09.040Moraga, G., Martı́nez-Navarrete, N., & Chiralt, A. (2004). Water sorption isotherms and glass transition in strawberries: influence of pretreatment. Journal of Food Engineering, 62(4), 315-321. doi:10.1016/s0260-8774(03)00245-0Moraga, G., Talens, P., Moraga, M. J., & Martínez-Navarrete, N. (2011). Implication of water activity and glass transition on the mechanical and optical properties of freeze-dried apple and banana slices. Journal of Food Engineering, 106(3), 212-219. doi:10.1016/j.jfoodeng.2011.05.009Pittia, P., & Sacchetti, G. (2008). Antiplasticization effect of water in amorphous foods. A review. Food Chemistry, 106(4), 1417-1427. doi:10.1016/j.foodchem.2007.03.077Rahman, M. S. (2006). State diagram of foods: Its potential use in food processing and product stability. Trends in Food Science & Technology, 17(3), 129-141. doi:10.1016/j.tifs.2005.09.009ROOS, Y., & KAREL, M. (1991). Plasticizing Effect of Water on Thermal Behavior and Crystallization of Amorphous Food Models. Journal of Food Science, 56(1), 38-43. doi:10.1111/j.1365-2621.1991.tb07970.xSogabe, T., Kawai, K., Kobayashi, R., Jothi, J. S., & Hagura, Y. (2018). Effects of porous structure and water plasticization on the mechanical glass transition temperature and textural properties of freeze-dried trehalose solid and cookie. Journal of Food Engineering, 217, 101-107. doi:10.1016/j.jfoodeng.2017.08.027Telis, V. R. N., & Martínez-Navarrete, N. (2009). Collapse and Color Changes in Grapefruit Juice Powder as Affected by Water Activity, Glass Transition, and Addition of Carbohydrate Polymers. Food Biophysics, 4(2), 83-93. doi:10.1007/s11483-009-9104-0Telis, V. R. N., & Martínez-Navarrete, N. (2010). Application of compression test in analysis of mechanical and color changes in grapefruit juice powder as related to glass transition and water activity. LWT - Food Science and Technology, 43(5), 744-751. doi:10.1016/j.lwt.2009.12.007Wan, J., Ding, Y., Zhou, G., Luo, S., Liu, C., & Liu, F. (2018). Sorption isotherm and state diagram for indica rice starch with and without soluble dietary fiber. Journal of Cereal Science, 80, 44-49. doi:10.1016/j.jcs.2018.01.003Wu, H.-Y., Sun, C.-B., & Liu, N. (2019). Effects of different cryoprotectants on microemulsion freeze-drying. Innovative Food Science & Emerging Technologies, 54, 28-33. doi:10.1016/j.ifset.2018.12.00

Quality of a powdered grapefruit product formulated with biopolymers obtained by freeze-drying and spray-drying

[EN] Freeze-drying and spray-drying are two techniques used to produce dehydrated food products. Both techniques are easy to use and offer high sensory, nutritive value, and functional quality to foods. However, both processes become difficult for foods with high sugar and acid content, such as fruits. This is because these products, once dehydrated, moisten quickly, causing a change in their physical properties, mainly in the mechanical aspects related to the start of a caking phenomenon. Therefore, incorporating high molecular weight biopolymers that act as facilitators or processors, prevent the structural collapse of the product. The aim of this study was to select the best process, between freeze-drying or spray-drying, to obtain a powdered grapefruit product with the higher quality. The impact of the biopolymers used to stabilize the powdered product was also tested. The properties analyzed were the solubility, wettability, hygroscopicity, porosity, and color of the powder together with the flow behavior, both in air and water. The results of this study show that using the freeze-drying technique, products have a better flow behavior, greater porosity, and a color more like fresh grapefruit. Biopolymers, especially when in combination, have a positive effect on the quality parameters studied. Practical Application The results of this study allow freeze-drying to be proposed as a process to obtain a grapefruit product with better properties, both powdered and rehydrated, than that obtained by spray-drying. On the other hand, although the incorporation of biopolymers is necessary to facilitate the process and stabilize the product, no significant differences have been found between the different formulations tested, although it seems that their combination favours some of the properties of the powder, such as solubility, hygroscopicity, wetting time and dispersibility.The authors thank the Ministerio de Economia y Competitividad and the Ministerio de Economia, Industria y Competitividad for the financial support given through the Projects AGL 2012-39103 and AGL 2017-89251-R (AEI/FEDER-UE), respectively. Luis A. Egas-Astudillo thanks the Secretary of Higher Education, Science, Technology and Innovation (SENECYT) of the Republic of Ecuador for the contribution to this research.Egas-Astudillo, LA.; Martínez Navarrete, N.; Camacho Vidal, MM. (2021). Quality of a powdered grapefruit product formulated with biopolymers obtained by freeze-drying and spray-drying. Journal of Food Science. 86(6):2255-2263. https://doi.org/10.1111/1750-3841.157502255226386

Impact of shelf temperature on a grapefruit puree temperature evolution during freeze-drying

[EN] The high nutritional and functional value of fruits justifies the use of freeze-drying to obtain high value-added products. As to identify in-line the drying end point, the usefulness of temperature evolution of a grapefruit puree, added or not with gum Arabic and bamboo fibre, when applying 20 or 40 oC as shelf temperature has been investigated. The obtained results point for the monitoring of the product's heating rate as to identify the end of sublimation in the sample, coinciding with the time this rate starts to decrease. On the other hand, the end point of the drying step of the freeze-drying process, optimised in terms of duration, is proposed to be related to the sample reaching a certain target temperature which does not necessarily match with the temperature of the chamber. In the concrete conditions of this study, it seems to be between 20 and 40 oC. As for the variables considered, the biopolymers added to the grapefruit puree did not affect the duration of the process and to increase the freeze-drier shelves temperature made it possible to reduce processing time by 40%.The authors thank the Ministerio de Economía y Competitividad and the Ministerio de Economía, Industria y Competitividad for the financial support given through the Projects AGL 2012-39103 and AGL 2017-89251-R (AEI/FEDER-UE), respectively. Egas-Astudillo, L.A thanks the Secretary of Higher Education, Science, Technology and Innovation (SENECYT) of the Republic of Ecuador for the contribution to this researchEgas-Astudillo, LA.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2021). Impact of shelf temperature on a grapefruit puree temperature evolution during freeze-drying. International Journal of Food Science & Technology. 56(1):413-419. https://doi.org/10.1111/ijfs.14656S41341956

Impact of the Freeze-Drying Conditions Applied to Obtain an Orange Snack on Energy Consumption

[EN] Nowadays, the consumer is looking for healthier, more attractive, ready-to-eat, and safer foodstuffs than fresh products. Despite freeze drying being known for providing high added value products, it is a slow process which is conducted at low pressures, so, in terms of energy consumption, it turns out to be quite costly for the food industry. With the purpose of obtaining a freeze-dried orange puree, previously formulated with gum Arabic and bamboo fiber, which can be offered to consumers as a snack at a low economic cost, the impact of the process conditions on energy consumption has been considered. The product temperature evolution and the energy consumption were registered during the drying of frozen samples at different combinations of chamber pressures (5 and 100 Pa) and shelf temperatures (30, 40 and 50 & DEG;C). In each case, the time processing was adapted in order to obtain a product with a water content under 5 g water/100 g product. In this study, the secondary drying stage was considered to start when the product reached the shelf temperature and both the pressure and the temperature affected the duration of primary and secondary drying stages. The results obtained led to the conclusion that the shorter duration of the process when working at 50 & DEG;C results in significant energy saving. Working at a lower pressure also contributes to a shortening of the drying time, thus reducing the energy consumption: the lower the temperature, the more marked the effect of the pressure.This research was funded by the Ministerio de Economia, Industria y Competitividad [AGL 2017-89251-R (AEI/FEDER-UE)] and the Ministerio de Universidades for the FPU grant [FPU14/02633] awarded to Andrea Silva.Silva Espinoza, MA.; Camacho Vidal, MM.; Martínez-Monzó, J.; Martínez-Navarrete, N. (2021). Impact of the Freeze-Drying Conditions Applied to Obtain an Orange Snack on Energy Consumption. Foods. 10(11):1-9. https://doi.org/10.3390/foods10112756S19101

Sorption Behavior, Glass Transition and Flowability of Powdered Orange Co-product

[EN] The aim of this study was to contribute 100% to the circular economy models of the agri-food industry through the valorization of the whole orange juice co-product in order to offer it as a natural, versatile, high quality, and stable powdered food ingredient for human nutrition. Turning it into a cost-effective innovative product, with added value due to its high content of bioactive compounds, would lead to an increased competitiveness of the industrial sectors working with natural fibers. To ensure its efficient use for this purpose, co-product powder was characterized from a technological point of view in terms of the physicochemical aspects related to the presence of water and its ability to remain free-flowing and non-agglomerated, allowing for easy handling. The results of this study ensure the flowability of the freeze-dried orange co-product powder according to both the angle of repose (40°) and porosity (83%) values. However, it was also characterized as a hygroscopic product; therefore, specified conditions for a proper storage of the powdered co-product should be defined. In this case, both the refrigeration temperature and a relative humidity of under 35% should be established in order to avoid glass transition, thus remaining a free-flowing powder.The authors thank the Ministerio de Economía y Competitividad (Spanish government) for the fnancial support given through the Project AGL 2017-89251-R (AEI/FEDER-UE).Camacho Vidal, MM.; Silva Espinoza, MA.; Martínez-Navarrete, N. (2021). Sorption Behavior, Glass Transition and Flowability of Powdered Orange Co-product. Materials Circular Economy (Online). 3:1-8. https://doi.org/10.1007/s42824-021-00036-018

Jam processing and storage effects on b-carotene and flavonoids content in grapefruit

[EN] Grapefruit phytochemicals (beta-carotene and flavonoids) stability after different jam processing was evaluated. Osmotic dehydration, microwave energy and conventional heating techniques have been used to obtain jam. beta-Carotene and individual flavonoids were analyzed by HPLC technique. The results showed that jam obtained from osmodehydrated fruit (ODJ) is the only that preserved completely the (beta-carotene content. All processes of production of jam significantly decreased the content of narirutin (NAT), poncirin (PON), naringenin (NAG) and quercetin (QUER), while naringin (NAR) remained stable. Jams obtained by applying a heat treatment showed significant lower values of NAG and QUER in comparison with ODJ. The jam obtained from osmodehydrated fruit, without being submitted to any heat treatment, showed at the end of storage the highest contents of naringin, hesperidin, neohesperidin, didymin, quercetin, poncirin and the total sum of analysed flavonoids. In general, the phytochemical loss in jams as a consequence of processing was lower than those provoked by storage effect.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Project AGL 2005-05994.Igual Ramo, M.; García Martínez, EM.; Camacho Vidal, MM.; Martínez Navarrete, N. (2013). Jam processing and storage effects on b-carotene and flavonoids content in grapefruit. Journal of Functional Foods. 5(2):736-744. https://doi.org/10.1016/jjf f.2013.01.019S7367445

Quality stability assessment of a strawberry-gel product during storage

A strawberry-gel product was formulated by using osmotic treatment. The osmotic solution (OS) used to dehydrate the fruit was mixed with carrageenan and employed to formulate the gel. In order to prevent a further dehydration of the fruit during product storage, the OS was previously diluted so that its water activity is the same as the dehydrated fruit. Changes in water, soluble solids, citric acid, ascorbic acid and anthocyanin contents, water activity, surface color, mechanical properties and volatile profile during 15 days of storage (5C) were evaluated. The use of the OS increased the nutritive and functional properties of the product. Changes in volatile profile, mechanical properties and color of the strawberry occur mainly in the first 2 days of storage and are not due to the presence of the gel matrix, as they occur also in the samples not placed in gel. The flux of anthocyanins from the fruit to the gel produces redness, giving a more attractive aspect to the formulated product. © 2009 Wiley Periodicals, Inc.The authors thank the Ministerio de Educacion y Ciencia and the Fondo Europeo de Desarrollo Regional (FEDER) for financial support throughout the projects AGL2002-01793 and AGL 2005-05994.Martín-Esparza, M.; Escriche Roberto, MI.; Penagos, L.; Martínez Navarrete, N. (2011). Quality stability assessment of a strawberry-gel product during storage. Journal of Food Process Engineering. 34(2):204-223. https://doi.org/10.1111/j.1745-4530.2008.00349.xS20422334