Using maltodextrin and state diagrams to improve thermal transitions in tilapia fillet (Oreochromis spp.).

BACKGROUND: Tilapia (Oreochromis spp.) in the form of frozen fillets is one of the fishes with the highest commercial production levels worldwide. However, protein denaturation, membrane rupture, and lipid oxidation are commonly observed in fillets when stored at standard commercial freezing temperatures for long periods. This study proposes, for the first time, the use of maltodextrin and state diagrams to define processing strategies and suitable storage temperatures for fresh and dehydrated tilapia fillets. Differential scanning calorimetry (DSC) was used to study the effect of maltodextrin weight fractions ( W MD ) of 0, 0.4, and 0.8 on the thermal transitions of tilapia fillets as a function of solid mass fractions ( W s ). RESULTS: The glass transition temperature curve ( T g vs . W s ) and characteristic parameters of maximal freeze concentration ( T g ' , T m ' , W s ' ) of tilapia increased significantly with the addition of maltodextrin. Using developed state diagrams, freezing and storage temperatures of -22 °C, -15 °C, and -10 °C (P < 0.05) for long-term preservation were defined for tilapia fillets produced with W MD of 0, 0.4, and 0.8. CONCLUSION: Maltodextrin is an excellent alternative as a cryoprotectant and drying aid to increase the thermal parameters of tilapia fillets by achieving frozen storage temperatures above the standard commercial freezing temperature of -18 °C. © 2023 Society of Chemical Industry.

The Influence of Maltodextrin on the Thermal Transitions and State Diagrams of Fruit Juice Model Systems.

The state diagram, which is defined as a stability map of different states and phases of a food as a function of the solid content and temperature, is regarded as fundamental approach in the design and optimization of processes or storage procedures of food in the low-, intermediate-, and high-moisture domains. Therefore, in this study, the effects of maltodextrin addition on the freezing points (Tm', Tm) and glass transition temperatures (Tg', Tg) required for the construction of state diagrams of fruit juice model systems by using differential scanning calorimetry methods was investigated. A D-optimal experimental design was used to prepare a total of 25 anhydrous model food systems at various dry mass fractions of fructose, glucose, sucrose, pectin, citric acid, and maltodextrin, in which this last component varied between 0 and 0.8. It was found that maltodextrin mass fractions higher than 0.4 are required to induce significant increases of Tg', Tm', Tg, and Tm curves. From this perspective, maltodextrin is a good alternative as a cryoprotectant and as a carrier agent in the food industry. Furthermore, solute-composition-based mathematical models were developed to evaluate the influence of the chemical composition on the thermal transitions and to predict the state diagrams of fruit juices at different maltodextrin mass fractions.

Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation.

For the first time, the novel experimental technique Temperature Modulated Optical Refractometry (TMOR) was employed for cocoa butter thermal transitions characterization. The average refractive index (NMEAN), the volume (v) change, and the volumetric expansion coefficient ( ß q ) as well as the dynamic quantities ß ' and ß â€³ (real and imaginary volumetric expansion coefficient, respectively) were monitored during cooling and heating and compared to the heat flow curves obtained via the standard technique dynamic scanning calorimetry (DSC). The investigation of these quantities showed that TMOR analysis can yield not only thermal transitions temperatures that are comparable to DSC results, but also some new thermal events that are not detected by DSC. This outcome suggests that TMOR might provide some additional insights on cocoa butter melting and crystallization by means of frequency-dependent measurements due to temperature modulation. This new information that can be accessed during temperature ramps might provide a deeper insight into thermal behavior of fat-based foods, evidencing TMOR value as a tool for thermal transitions investigation.

Effect of the desiccation tolerance and cryopreservation methods on the viability of Citrus limon L. Burm cv. Eureka seeds.

Cryopreservation of the germplasm for long-term periods is of great importance to maintain the genetic resource. Argentina is one of the world's highest lemon producing country. The performance of different cooling/warming rates in the cryopreservation method of Citrus limon L. Burm cv. Eureka seeds and their influence on the interval of optimal moisture content in the desiccation stage were analyzed. Water sorption isotherm was determined and modeled using D'Arcy & Watt equation; it provided important information concerning the amounts of water associated to strong, weak and multimolecular binding sites along the sorption isotherm. Seeds tolerated a wide range of desiccation conditions (0.180%), however desiccation to 0.0526 g H2O g-1 d.b. (aw = 0.0901) produced a significant loss of viability. Differential Scanning Calorimetry was used to identify the thermal transitions of lipids and water in the seed; enthalpies were used to calculate the unfrozen water fraction (0.19 g H2O g-1 d.b. corresponding to aw = 0.64). Two cooling/warming rates were tested on desiccated seeds (0.110.64 corresponding to the unfrozen water fraction. The use of higher cooling/warming rates enables a wider range of desiccation conditions (0.33

An experimental confirmation of thermal transitions in native and regenerated spider silks.

Biological structures such as spider silks are formed by proteins. The physical properties of such proteins are determined by environmental conditions such as temperature and humidity. In this paper, we confirm the thermal transitions that take place in spider silks using differential scanning calorimetry and study how the interaction of spider silk proteins with water affects the onset temperatures for these thermal processes. Native fibres and regenerated films of dragline silk and egg sac silk from Argiope argentata spiders were used to study thermal transitions of protein based structures. For the first time, differential scanning calorimetry (DSC) tests were carried out with spider silk samples of relatively large mass (10mg). Previous attempts of DSC tests applied to spider silk samples failed to detect thermal transitions in a conclusive way. The tests reported here, however, show thermal transitions on both natural and regenerated samples that are in agreement with results from dynamic mechanical analysis (DMA) tests reported in the literature. The water content on spider silks seems to lower the temperatures at which such thermal transitions take place. The results also confirm that the amorphous regions of native and regenerated spider silk and silk worm silk give rise to similar thermal transitions.