Water loss, gain or transfer results in a decline in the overall quality of food. The aim of this study was to form a uniform layer of sodium alginate-based edible coating (1.25% sodium alginate, 2% glycerol, 0.2% sunflower oil, 1% span 80, 0.2% tween 80, (w/w)) and investigate the effects on the water barrier characteristics of fresh-cut cantaloupe and strawberries. To this end, a uniform and continuous edible film formation was achieved (0.187 ± 0.076 mm and 0.235 ± 0.077 mm for cantaloupe and strawberries, respectively) with an additional immersion step into a calcium solution at the very beginning of the coating process. The coating application was effective in significantly reducing the water loss (%) of the cantaloupe pieces. However, no significant effect was observed in water vapor resistance results and weight change measurements in a climate chamber (80%→60% relative humidity (RH) at 10 °C). External packaging conditions (i.e., closed, perforated, and open) were not significantly effective on water activity (a_w) values of cantaloupe, but were effective for strawberry values. In general, the coating application promoted the water loss of strawberry samples. Additionally, the water vapor transmission rate of stand-alone films was determined (2131 g·100 µm/(m²·d·bar) under constant environmental conditions (23 °C, 100%→50% RH) due to the ability to also evaluate the efficacy in ideal conditions.

Chocolate bars with whole nuts are a popular type of chocolate. However, their shelf life is limited by the roasted hazelnuts, which can become rancid or cause fat bloom, a whitish layer on the chocolate surface. Both are thought to be related to the nut oil that rises to the surface. Surface oil is prone to rancidity due to contact with oxygen. In addition, when the nuts are used in chocolate, the surface oil can be washed off by the chocolate during mixing or can migrate into and through the chocolate to become visible as fat bloom. Although fat bloom tends to occur on only a few nuts in a bar, the presence of fat bloom on just one nut is enough to reduce enjoyment because consumers associate it with mold. In this study, the influence of origin and roasting conditions on both quality changes was investigated. Hazelnuts of caliber 11–13 mm harvested from two different regions of Turkey, namely, Akçakoca and Ordu, were subjected to four different roasting conditions. The roasting process was performed either at low temperature for a long time (at 142°C for 30 or 50 min) or at high temperature for a short time (at 200°C for 7 or 9.5 min) in an industrial scale roaster (capacity of 50 kg per batch). Assessment of oxygen consumption and hexanal headspace measurement, both indicative of rancidity, showed increased oxidative stability for nuts roasted at the lower temperature. Roasted nuts from all roasting trials were used to produce various nut chocolate bars for storage tests. During these storage tests, the development of fat bloom was quantified using the DigiEye colorimetric measurement system, which is a box with defined lighting conditions and a fixed and calibrated digital camera. Images taken with this system were used to evaluate the whiteness index, an indicator of fat bloom. The migration of oil from the roasted hazelnuts into liquid cocoa butter was studied in a model system. Higher oxygen consumption and hexanal formation could be clearly related to the higher roasting temperature of 200°C. Oil migration in the model system as well as in the chocolate bars was independent from the roasting conditions, but hazelnuts from Ordu showed a higher oil release than those from Akçakoca. Fat bloom formation was clearly related to the storage temperature of the chocolate bars but independent of the origin of the hazelnuts and the roasting conditions. However, in individual bars with the same production processes, hazelnuts of the same origin and roasting conditions showed fat bloom only on some nuts and not on all, indicating that there are additional factors affecting fat bloom formation.

The conching process plays a key role in determining the sensory and rheological properties of dark chocolate. To further understand this process, changes in the chocolate mass during plastic conching were investigated on a time-resolved basis with varying conching temperature, shear direction, and with or without the presence of residue from previous trials (pre-charge) on the conche vessel wall. Six selected odorants (acetic acid, benzaldehyde, linalool, 2,3,5,6-tetramethylpyrazine, 2-phenylethanol, 2-phenylethyl acetate) were quantified in fat and particle phases of chocolate masses. Particularly at elevated conching temperature, the odorant concentrations were found to decrease (up to 78.0% in the fat phase). The highest concentrations of desired odorants were determined mostly after conching without pre-charge. During conching, odorants were observed to accumulate increasingly in the fat phase (up to 91.7%) with decreasing odorant polarity. Similarly, it was found that conching temperature and the absence of pre-charge had the highest impact on the rheological properties of the chocolate mass, resulting in lowest and highest complex viscosity, respectively. In conclusion, some positive outcomes of conching, namely the retention of desired odorants and the reduction of viscosity, were inversely related at elevated temperature or in the absence of pre-charge, necessitating compromises to achieve optimal flow properties and flavor. Our results contribute to a deeper understanding of the influence of conching on the quality of dark chocolate by providing insights into the complexity of aroma migration and rheological changes during conching.