Quality and Drying Characteristics of Apple Cubes Subjected to Combined Drying (FD Pre-Drying and HAD Finish-Drying)

Abstract

The drying methods tested were hot-air drying (HAD) and freeze-drying (FD), as well as a combination of blanching (100C, 1 min) prior to FD pre-drying and HAD finish drying. The effect of drying methods on moisture content, temperature, energy consumption, duration of drying, rehydration properties, color, texture and sensory were determined. Apple's HAD and FD kinetics was described by an exponential and third-degree polynomial model, while the combined drying-blanching prior to freeze pre-drying and hot-air finish-drying (BFD-HAD) kinetics consisted of two periods: polynomial until a converting point and exponential beyond that point. Among the products, the quality of apple samples processed by FD was the best, followed by BFD-HAD, whereas the products made using HAD were the worst. The drying times obtained for HAD and BFD-HAD were shorter than the drying times obtained for FD. The best BFD-HAD process, from quality and energy consumption considerations, was found to a moisture content of 30% w.b. (BFD time: 12 h), followed by 3 h of HAD. It was observed that BFD-HAD can reduce by about 8 h the time needed for FD. PRACTICAL APPLICATIONSApple (Malus domestica L.) is one of the most widely grown fruit crops in the world. Available in fresh and processed forms, apples are rich source of vitamins, organic acids, polyphenols, anthocyanins and minerals. Currently, dehydrating is a frequent practice since dried apples are included in numerous processed foods such as snack products, integral breakfast foods, etc. The aim of this article is to examine the effectiveness of freeze-drying enhanced with two-stage vacuum freeze and hot-air drying. It can be suggested to apply the blanching as pretreatments and combined drying (FD-HAD) for reduction of operational cost. Our research work confirmed that BFD-HAD is a good alternative instead of the FD. The development of new drying techniques possibility for apple with good physical, chemical properties may be of interest in order to the market supply (food supplement, functional food, etc.).Freeze-dried products achieve a high rating for physical, chemical properties: rapid rehydration, little shrinkage, high retention of color, low bulk density, high chemical content, low water activity and superior taste, flavor, aroma. However, FD is very costly because of high investment and operational costs (long process time), limit its application to industrial scale. Long drying times are caused by a high heat transfer resistance that especially exist in the final

Novel Combined Freeze-Drying and Instant Controlled Pressure Drop Drying for Restructured Carrot-Potato Chips: Optimized by Response Surface Method

“…Huang et al [12] found that the restructured chips containing potato and apple dried by combined microwave and freeze-drying (MFD) obtained the best quality, and the drying time of MFD was shorter than that of FD. In addition, the combination of FD and hot-air-drying for apple cubes was confirmed to be a good alternative instead of mere FD treatment [13]. According to these previous reports, the drying time and energy consumption for FD could be significantly reduced through applying several combination methods, with the products comparatively superior to hot-air-dried products and nearer in quality to FD products [14].…”

“…Additionally, the final moisture content slowly decreased with increasing of the equilibrium temperature of DIC when the amount of carrot was constant (30%) (Figure 2(b)). This could be explained by the fact that the rate of water diffusion is proportional to the material temperature and time of heat during drying process [13]. The 2 of the regression model of the final moisture content of products was 0.956, which indicated that 95.6% of the total variability in the final moisture content of the restructured carrot-potato chips could be explained by this model ( Table 3 carrot, respectively, the moisture content of 0.30 g/g d.b.…”

Alphonso Mango Enrichment with Aloe Vera (Aloe barbadensis) by Sequential Drying: Optimization, Kinetics and Quality Evaluation

“…Various works have been reported on preservation of such valuable and perishable fruits using freeze‐drying (FD) alone, hot‐air drying (HAD) or a combination of blanching, FD and HAD (BFD‐HAD) (Antal et al . ). But these processes have negative impact on the finally obtained dried product.…”

Suitable model for thin-layer drying of root vegetables and onion

“…The mathematical form of empirical models does not require the consideration of the theory of drying, therefore their parameters are without physical meaning (Kaleta et al, 2013). On account of their simplicity, the models discussed are applied to describe the drying characteristics of different products such as apples (Antal et al, 2015;Atalay et al, 2017), blueberries (Yu et al, 2017), carrots (Aghbashlo et al, 2011;Mahapatra and Tripathy, 2018), canola (Gazor and Mohsenimanesh, 2010), cashew (Dhanushkodi et al, 2017), dill leaves (Motevali et al, 2013), garlic (Younis et al, 2018), green bean (Doymaz et al, 2015;Tekin et al, 2017), Hass avocado seeds (Avhad and Marchetti, 2016), kiwi fruit (Tian et al, 2015), Moroccan rosemary leaves (Mghazli et al, 2017), peach (Doymaz, 2014), pumpkin (Junqueira et al, 2017), rice (Hacıhafızoğlu et al, 2008), spinach leaves (Doymaz, 2009), sweet basil (Phoungchandang and Kongpim, 2012), tomato (Azeez et al, 2017), Vernonia amygdalina leaves (Alara et al, 2017). Some authors have described the effect of drying variables on the parameters of empirical models, in these cases such models may be considered to be more general.…”