The effects of added sugars and alcohols on the induction of crystallization and the stability of the freeze-dried peki (caryocar brasiliense camb.) fruit pulps

LWT - Food Science and Technology 43 (2010) 934–941

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LWT - Food Science and Technology
journal homepage: www.elsevier.com/locate/lwt

The effects of added sugars and alcohols on the induction of crystallization and the stability of the freeze-dried peki (Caryocar brasiliense Camb.) fruit pulps
ˆ Cibele Cristina de Oliveira Alves, Jaime Vilela deResende*, Monica Elisabeth Torres Prado, Rafael Souza Ribeiro Cruvinel
Department of Food Science, Federal University of Lavras, P.O. Box 3037, 37200-000 Lavras, Minas Gerais, Brazil

a r t i c l e i n f o
Article history: Received 9 July 2009 Received in revised form 26 January 2010 Accepted 29 January 2010 Keywords: Freeze-drying Crystallization induction Carotenoids Water sorptionCollapse

a b s t r a c t
Peki (Caryocar brasiliense Camb.) is a Brazilian fruit with an extremely high b-carotene content, but the b-carotene is unstable under dry storage conditions. This work reports on the product development and stability of freeze-dried peki fruit pulp. Freeze-dried products were made by adding alcohols (ethanol and isopropyl alcohol; at concentrations of 0, 5 and 10 mL/100 mLof extract) and sugars (sucrose and fructose; at concentrations of 0, 5 and 10 g/100 mL of extract) to the peki fruit pulps followed by freezedrying. Scanning electron microscopy was used to analyze the microstructure of the freeze-dried products by visualizing the crystallized forms. The product hardness and total carotenoid content following the different treatments were measured using atexture analyzer and a spectrophotometer, respectively. The stability of these foods was evaluated by their water sorption during their storage in various relative humidity environments at 25  C. There were characteristic differences in their hygroscopic behaviors. The pretreatment with sucrose and ethanol improved the freeze-dried product and yielded a lower number of collapsed structures. Changesduring the storage were observed. The pulp pretreated with sucrose was amorphous and metastable, but the drying process was accelerated by the presence of alcohol (mainly ethanol), which resulted in protected structures without any sign of collapse. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction Peki (Caryocar brasiliense Camb.) is a typical cariocacea that can be found evenlydistributed throughout the southeastern, central western and northeastern regions of Brazil, where it represents the main source of income for the population. Recently, the fruit has gained nutritional and economic importance, and its commerce has expanded beyond the Brazilian borders as it is now exported to other countries, including Australia. Peki fruit is consumed for its unique flavor and aroma aswell as its high nutritional value. Peki has an extremely high b-carotene content (Ribeiro, 2000) that is not stable during storage. The importance of some carotenoids as precursors of vitamin A in human nutrition is well known, and b-carotene is the most powerful of these provitamins. This is significant because vitamin A deficiency is considered a nutritional problem of populations in the poorestregions of Brazil. Peki oil is another sub-product that is extracted from the fruit pulp. According to Vilas Boas (2004), peki pulp is composed of
* Corresponding author. Tel.: þ55 35 3829 1659; fax: þ55 35 3829 1401. E-mail address: jvresende@dca.ufla.br (J.V. de Resende). 0023-6438/$ – see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2010.01.029

49.2% moisture,20.5% lipids, 4.2% protein, 18.9% carbohydrate, 6.8% fibers, 9.4% minerals and 0.9–2.0% titratable acidity. With its widespread use, peki is an important fruit consumed by a large portion of the Brazilian population, and all parts of the peki fruit are used for various purposes. However, peki fruit harvests occur only during the months of November to February. This is a limiting factor in the...