Hindawi Journal of Food Quality Volume 2018, Article ID 6317943, 10 pages https://doi.org/10.1155/2018/6317943 Research Article Convective Drying of Osmo-Treated Abalone (Haliotis rufescens) Slices: Diffusion, Modeling, and Quality Features Roberto Lemus-Mondaca ,1 Sebastian Pizarro-Oteíza,2 Mario Perez-Won,2 and Gipsy Tabilo-Munizaga3 1 Departamento de Ciencia de los Alimentos y Tecnolog´ıa Qu´ımica, Facultad de Ciencias Qu´ımicas y Farmaceuticas,´ Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile 2Departamento de Ingenier´ıa en Alimentos, Universidad de La Serena, Av. Raul´ Bitran´ 1305, La Serena, Chile 3Departamento de Ingenier´ıa en Alimentos, Universidad del B´ıo-B´ıo,Av.Andres´ Bello 720, Chillan,´ Chile Correspondence should be addressed to Roberto Lemus-Mondaca; [email protected] Received 17 October 2017; Revised 6 January 2018; Accepted 14 February 2018; Published 24 April 2018 Academic Editor: Alex Martynenko Copyright © 2018 Roberto Lemus-Mondaca et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te focus of this research was based on the application of an osmotic pretreatment (15% NaCl) for drying abalone slices, and it ∘ evaluates the infuence of hot-air drying temperature (40–80 C) on the product quality. In addition, the mass transfer kinetics of salt and water was also studied. Te optimal time of the osmotic treatment was established until reaching a pseudo equilibrium state −9 2 of the water and salt content (290 min). Te water efective difusivity values during drying ranged from 3.76 to 4.75 × 10 m /s ∘ for three selected temperatures (40, 60, and 80 C). In addition, experimental data were ftted by Weibull distribution model. Te modifed Weibull model provided good ftting of experimental data according to applied statistical tests. Regarding the evaluated ∘ quality parameters, the color of the surface showed a change more signifcant at high temperature (80 C), whereas the nonenzymatic browning and texture showed a decrease during drying process mainly due to changes in protein matrix and rehydration rates, ∘ respectively. In particular, working at 60 C resulted in dried samples with the highest quality parameters. 1. Introduction crustaceans (lobsters), cephalopods (cuttlefsh), and salmon species, all with growing demand around the world [3]. Te red abalone (Haliotis rufensces) is an herbivorous gastro- Marine products are extremely perishable and the time pod mollusk living naturally in the bedrock of water between to spoilage depends mainly on species, handling, processing, 1 and 30 m depth. Te culture of abalone has increased and storage temperature [4]. Currently, these products are considerably, since it is highly appreciated as a seafood of high sold as frozen, canned, or cooked frozen. However, the proce- commercial value, especially in countries like China and dures involved can afect the quality attributes such as texture Japan [1], enjoying the frm texture, as well as cooked product and taste [5]. Terefore, new treatments and/or processes are tenderness [2]. Tis species of abalone is considered exotic needed to minimize biological reactions and physicochemi- seafood and is one of the most expensive seafood products cal leading to the loss of food quality [5] in order to increase (Briones-Labarca et al., 2011). From the above, the Aquacul- product shelf-life. ture in Chile has grown considerably, while exports have been Many studies have focused on diferent methods of important afer copper, forestry, and fruits, considering that preservation, with the hot-air drying being one of the most for the future it will be one of the most important sources important processes [6, 7]. Tis process reduces the water of food for the world. Tis way, the cultivation has been cur- activity through loss of moisture, preventing the growth rently focused on univalve (red abalone), bivalves (oysters), and reproduction of microorganisms [8]. Convective drying 2 Journal of Food Quality is one of the most used industrial methods for drying food during experiments. Te brine was agitated continuously in a and biological materials, in order to preserve its quality water bath (Quimis, Q.215.2, Sao Paulo, Brazil) to maintain a and stability, so avoiding spoilage and contamination during uniform temperature. Te osmotic process was made up of the storage period [1, 9, 10]. However, it is known that the regular time intervals (0, 15, 30, 45, 60, 120, 180, 240, 300, drying process causes the loss of function of the cell mem- 360, and 420 min) until reaching an osmotic pseudo equilib- branes especially when the temperature increases causing rium. Moisture content was determined by AOAC method ∘ signifcant changes in sensory and nutritional food quality. n 934.06 (AOAC, 1990) using an analytic balance (Chyo, Tese disadvantages can be reduced using a combination of Jex120, Kyoto, Japan) with a ±0.0001 g accuracy and vacuum diferent pretreatments. From these pretreatments, the most drying oven (Gallenkamp, OVA031, Leicester, UK). As to salt widely used in convective drying are osmotic dehydration, content, this one was measured by Mohr method [22], where blanching, microwave drying, and enzyme solution, among salt content was expressed as g NaCl/100 g sample. All the ex- others.[11].Commonly,marineproductsareimmersedin perimental determination was performed in triplicate. concentrated solutions to impregnate them with salt and/or other curing ingredients (sucrose, glucose, fructose, glycerol, sorbitol, and sodium chloride) to prolong shelf-life [5, 12]. 2.2. Drying Procedure. Once the osmotic balance of the salt Te osmotic pretreatment scarcely afects the color, favor, and water content has been reached, convective drying was and texture of these products. It diminishes also the loss of carried out. Te convective drying process was performed in a nourishing substances and does not have a high exigency of convective dryer tray designed and fabricated by the Depart- ment of Food Engineering at the University of La Serena, energy due to the used temperatures, generally that of the ∘ environment. Chile [7]. Drying temperatures were 40, 60, and 80 Cata 1.5 ± 0.2 Knowledge of the drying kinetics is used not only in constant air velocity m/s for each test with an envi- 18.0 ± 0.1∘ 68.1 ± 3.8 the evaluation process, but rather to analyze and predict the ronmental condition of Cand %RH,the drying process variables to minimize damage to fnal product latter being measured by a digital hygrothermometer (Extech and optimize drying time and excessive energy consumption Instrument Inc., 451112, Waltham, MA, USA). Te experi- [1,9,13].Tisanalysiscanbeperformedwithdiferentmathe- ments ended when a state of pseudo equilibrium was reached matical models such as Newton, Henderson-Pabis, Page, at a constant weight between 22–18% humidity and 0.73–0.62 Modifed Page, Weibull, Two-Term, Midilli-Kucuk, and Log- water activity according to the temperatures evaluated. Te arithmic models [14, 15]. Nonetheless, in the literature, there samples were sealed in polyethylene bags and each experi- is no information available about the use of Weibull distri- ment was made in triplicate. Te samples were sealed in poly- bution model for the marine product dehydration [16]. Te ethylene bags and each experiment was made in triplicate. Weibull model has been used to describe, among others, the kinetics: high pressure removal of Bacillus subtilis [17], rehy- 2.3. Difusion Coefcient. In order to study the phenomena dration of breakfast cereals [18], loss of water during osmotic of mass transfer during osmotic dehydration and convective dehydration of food [19], and heat resistance of Bacillus drying process of abalone samples, two components were cereus [20]. considered in each process: (a) the water loss and salt gain Tus, the aim of this research was to study the infuence forODand(b)thewaterlossforconvectivedrying.Fick’s of drying temperature on the mass transfer kinetics of second law has been widely used to describe the dynamics osmotically pretreated abalone slices and to evaluate diferent of the diferent drying processes for biological materials [23]. quality characteristics such as color, rehydration capacity, Te mathematical solution of Fick’s second law was used texture profle (TPA), no enzymatic browning (NEB), total to describe the period, when internal mass transfer (water volatile basic nitrogen (TVBN), and antioxidant capacity of or salt) is the controlling mechanism and one-dimensional thedried-rehydratedproduct. transport in an infnite slab [24], shown in (1), which corresponds to the geometry of a semi-infnite slab. Tus, the 2. Materials and Methods variables of difusion model are moisture loss (MR) (see (2)) andsaltgainrate(SR)(see(3))[25],representedasfollows: 2.1. Samples Preparation and Osmotic Pretreatment. Te red abalone (Haliotis rufescens) samples were collected from an aquaculture Company (Live Seafood Chile SA, Coquimbo, ∞ 8 � (2� + 1) �2� 20.0 ± 0.2 = ∑ ( � ). Chile). Tese samples with a weight of gwere MR or SR (2� + 1) �2 exp 4�2 (1) delivered alive from the company to the university laboratory. �=0 Ten, they were slaughtered, shucked, cleaned, and washed with fresh water until the blue pigment haemocyanin was removed. Finally, the samples were cut into slices of 10 mm Forsufcientlylongdryingtimes,thefrstterm(�=0)inthe long × 0.1 mm wide × 0.1 thick to consider one dimension series expansion of (1) gives a good estimation of the solution and were immersed in a salt solution (NaCl, 15 g/100 mL) and can be applied to determine the water and salt difusion ∘ at 20 C as proposed by Lemus-Mondaca et al. [13] in the coefcients, (2) and (3), respectively [25]. Ten, Fick’s 2nd law 2 2 red abalone (Haliotis rufescens) and Boudhrioua et al. [21] in (see (1)) can be linearized, from the slope (=� ��/4� ), where sardinefllets.Tebrinetosampleratiowasmaintainedat8:1 ��� and ��� are moisture loss or salt gain, respectively, that in order to not dilute the osmotic solution by water removal can be obtained.