Band 17, Heft 10

A pilot-scale vacuum dryer with visualization system was used to study the drying characteristics of the whole blueberry pulp. The heating temperature, operating pressure and initial material thickness had significant effects on the drying characteristics and the retentions of total monomeric anthocyanins and vitamin C in dried blueberry powder ( P  < 0.05). According the heat transfer mode inside the material, the whole drying process could be divided into three periods: the boiling drying period, the convective drying period, and the conductive drying period. Most of water in the material was evaporated in the boiling and convective drying period. Considering the drying characteristics and dried product quality comprehensively, an optimal drying condition for whole blueberry pulp were: heating temperature 70 °C, operating pressure 1 kPa, and the initial material thickness 5 mm. It further compared the drying time, nutrients retention, hygroscopicity and microstructure of the product obtained by vacuum and vacuum freeze drying. The drying time of vacuum drying (1.2 h) was much shorter than that of vacuum freeze drying (44 h); the retentions of the total monomeric anthocyanins and vitamin C in dried blueberry powder of vacuum drying (67.9, 46.7%) were lower than that of vacuum freeze drying (79.0, 85.8%); while the hygroscopicity of vacuum dried powder was less than that of the freeze-dried product. The SEM images displayed that the surface of the vacuum-dried blueberry powder was porous, and the vacuum freeze-dried product was lamellar.

The aim of this work is the simulation of volumetric strain of tuberous crop during drying. We propose a poroelastic model for predicting the drying kinetics and volume loss of potato cubes during convective drying. The Biot’s theory of poroelasticity was used, which considers the Lamé parameters, Young’s modulus and Poisson’s ratio. Drying kinetics and volumetric strain were modeled and compared versus experimental data. An X-ray microtomograph coupled with image analysis was used to visualize the shape and size of the samples during drying. Drying experiments were conducted at 50, 60 and 70 °C, 20% RH, with an air velocity of 1 and 2 m/s. The drying process was interrupted several times to perform tomographic acquisitions. We found a period of ideal shrinkage, nevertheless, the volumetric strain reveals a kinetic behavior over time. The model computes the volumetric strain, which describes correctly the experimental data obtained by microtomography.

Marinated chicken wings is one of the popular marinated meat products in China. Here, electronic nose (e-nose) and solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) were used to detect volatile components of four different treatment marinated chicken wings (neither irradiated nor added phytic acid and tea polyphenols, A1; added phytic acid and tea polyphenols but no irradiated, A2; irradiated with 4 kGy irradiation but not added phytic acid and tea polyphenols, A3; irradiated with 4 kGy irradiation and added phytic acid and tea polyphenols, A4). Then odor activity value (OAV) and principal component analysis (PCA) were utilized to analyze their key flavor compounds. E-nose analysis found that antioxidant has a great impact on the odor of the marinated chicken wings, while the irradiation treatment has little effect on it. Besides, the irradiation treatment can reduce the unpleasant odor caused by antioxidants in certain. Through SPME-GC-MS, 101 volatile compounds were identified in four groups. After analysis, the antioxidants can inhibit the production of some volatile compounds, while irradiation treatment will relieve this phenomenon. This result is consistent with the e-nose. Following OAV, PCA analysis and sensory evaluation further verified the above conclusions.

Heating under pressure treatment (HUP) is a method which can keep the complete form of quinoa grain after processing, which is beneficial to the development of subsequent products. The conditions for quinoa heating under pressure was optimized by response surface methodology to be: quinoa grains were regulated with adding 6.3% of pH 7.0 water and heated under 0.36 MPa pressure for 3–5 min, resulting in the predicted maxima of total phenolic content (TPC), Flavonoid and Saponin content were 313.21 mg GAE/100 g, 1.621 mg/g, and 16.78 mg/g and the values of OH Scavenging Rate, DPPH Scavenging Rate, ABST + Scavenging Rate were 69.45, 91.73, and 52.38% separately. The content of flavonoid and saponin in the HUP samples were more than that in the boiled, baked, and extruded samples, which were close to that in raw quinoa sample, and meaning high retention of active phytochemicals and antioxidation activity in HUP quinoa. The hydroxyl radical scavenging rate is related to the content of polyphenol, flavonoid and saponin.

In this study, the physico-chemical properties of tomato powder produced by an optimized freeze drying process (FDP) were evaluated. With the lycopene content as the dependent variable, the optimum FDP conditions (i.e., thermal cracking time of 62 s, ascorbic acid addition amount [0.13%], and particle size [Dv 90 ] of 163 μm) were obtained through response surface methodology (RSM). The results showed that the content of lycopene in the prepared tomato powder was higher than that in two commercial products. Aldehydes were the main components among 25 kinds of aromatic substances detected in tomato powder. The values of a * and a * / b * , the hydration properties including water holding capacity (WHC) and oil binding capacity (OBC), and the content of total acid, ascorbic acid, and soluble solids were improved compared to commercial spray dried and freeze dried samples. All the above results suggested that FDP was an adequate procedure for the production of high-quality tomato powder.

Nectarine powder is widely used in the industries of baking and confectionery. The production of nectarine powder can be made by several drying techniques such as spray, tray, drum, freeze, and foam mat. This study was aimed to optimize the parameters of the nectarine foaming process. Besides, hot air-assisted foam-mat drying of nectarine was carried out to evaluate the effect of different temperatures (50, 60, and 70 °C) on drying kinetics, physicochemical and powder properties of nectarine powder. Factors studied were egg albumin concentration, carboxymethyl cellulose concentration, and whipping time that varied between 10 and 30% (by weight), 0.2–0.8% (by weight), and 3–5 min, respectively. Optimum conditions were determined as 30% of egg albumin, 0.8% carboxymethyl cellulose, and a whipping time of 5 min to get maximum foam expansion, high foam stability, and minimum foam density. The drying rate and effective moisture diffusivity of nectarine foam powder increased with increasing drying temperature. Carr Index and Hauser Ratio values were in the range of 32.31–47.00 and 1.48–2.00, respectively. Foamed nectarine powder dried at 70 °C had the lowest hygroscopicity value and the highest wettability value. No significant difference was found between the powders’ porosity ( p  > 0.05). The powders produced at 50 °C resulted in higher total phenolic, vitamin C, and carotenoid content.

The purity is accounted for one of the main characteristics of sugar beet juice in the sugar production process. In this regard, in the paper, the impact of slicing parameters including blade type, slicing angle from 0 to 90°, slicing thickness from 3 to 6 mm, and preheating duration from 3 to 15 min was studied on juice purity using Response Surface Methodology (RSM). The Genetic Algorithm (GA) technique was also employed to find the optimum values of variables to reach the highest juice purity. The results indicated that the quadratic model was the best model to predict juice purity. The Findings presented that as cossette thickness and slicing angle increased, the juice purity was improved. Optimization of the quadratic model by GA showed the best cossette thickness was 6 mm for both blades. The results of optimization indicated that 92.25 and 94.45% juice purities could be obtained from optimum conditions.