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The effects of conventional-C, carbon fiber plate assisted cabinet heater-CPAC, ohmic-OT, and microwave thawing-MT techniques on changes of some quality characteristics and resistant starch (RS) content of potato (Solanum tuberosum L.) cubes (18 3 18 3 18 mm) were investigated. The effects of blanching prior to the freezing on thawing characteristics were also determined. The thawing times of non-blanched samples were determined as 23,580 6 485 s, 5360 6 40 s, 205 6 18.25 s and 19.26 6 1.49 s for conventional, CPAC, OT, and MT methods, respectively. The blanching process increased the thawing times in general. OT and CPAC thawing methods served lower RS content for thawed potato samples. The potato cubes thawed by OT and MT were softer than C and CPAC thawed potato cubes (P < 0.05). The highest color change was found for MT of blanched samples and conventional thawing of non-blanched samples. The electrical methods could be alternative thawing methods in terms of providing shorter thawing times and desirable changes on some quality characteristics. PRACTICAL APPLICATIONSThe conventional thawing of high amount of frozen food products have posed a problem for catering industry. The long thawing time, drip loss issues, quality loses and possible microbial spoilage are lacks of conventional thawing method. The electroheating methods such as ohmic, microwave and unique carbon fiber plate assisted cabinet heating were employed as alternative thawing techniques. Thawing time of potato cubes were shortened and quality characteristics, such as drip loss, texture profile, color properties and resistant starch (RS), were improved by novel thawing methods. The obtained results reveal that the application of alternative thawing methods may lead to decreasing of the operating cost due to shorter process time and minimizing the changes in color, texture and nutritional compounds.

Thin-layer drying behaviour of dill leaves samples under three different infrared radiation power intensities was investigated. Diffusion Approach was found to be the best model that describes the drying behaviour of dill leaves. Effective diffusivity values were 6.97 × 10−9, 6.84 × 10−9 and 8.96 × 10−9 m2/s for power intensities of 1790, 1970 and 2070 W/m2, respectively. According to the first and second law efficiencies, the infrared drying system was more efficient at higher power intensities (p < 0.05). However, the total colour change was maximum at the highest power intensity. For the investigated infrared drying conditions, 1970 W/m2 was recommended as the best-infrared power intensity applied for drying of dill leaves by taking into account both performance analyses and quality changes.

BACKGROUND: Vacuum evaporation (VE) process is widely utilized in fruit juice evaporation to preserve quality attributes of final product. However, it has some disadvantages such as possible degradation of aroma components or volatile fatty acids due to long process time, and low energy efficiency of process. Pomegranate juice having 17.5% total soluble solid (TSS) content was evaporated to 40% TSS by ohmic heating assisted vacuum evaporation (OVE; 7.5, 10 and 12.5 V cm −1 ) and VE in the present study. The effects of the evaporation methods on pH, titratable acidity and colour values, antioxidant activity (AA), total monomeric anthocyanin (TMA), total phenolic content (TPC), hydroxymethylfurfural (HMF) and invert sugar content of pomegranate juice concentrates were compared. RESULTS:The colour properties, TMA, TPC and AA values of pomegranate juice concentrates evaporated by OVE were more influenced than those evaporated by VE. The degradation of sugars was minimized for OVE processes at high voltage gradients (10 and 12.5 V cm −1 ), and HMF content of pomegranate juice concentrated by OVE was lower than VE. CONCLUSION: It is thought that electrochemical reactions occurred because of the use of titanium electrodes during the OVE process caused these quality changes in pomegranate juice concentrates having high acidity. Hence, it was concluded that the utilization of relatively more electrochemically inert electrodes should be investigated in further studies to better evaluate the of influence of OVE method on quality attributes of different fruit juices.where subscript '0' indicated colour properties of raw material, and subscript 'i' indicated colour properties of juice concentrates. Statistical evaluationStatistical evaluations were performed by using SPSS 16.0 (IBM, USA) program. The difference between the effects of evaporation methods on colour properties, TPC, total and invert sugar content, TMA, HMF and AA were determined by using analysis of variance (ANOVA) test. The confidence interval was chosen as 95%.