Moisture sorption characteristics of ready-to-eat snack food enriched with purslane leaves

Characterization of flours from the aroeira leaf (Schinus terebinthifolius Raddi), obtained by different drying methods

The present work aimed at the development and characterization of aroeira leaf flour (Schinus terebinthifolius Raddi), obtained by lyophilization and drying in an air circulation oven. The technological, physical, physico-chemical, morphological, functional, and microbiological aspects were analyzed. Physico-chemical analysis identified the following properties with values provided respectively for fresh leaves (FOin) and flours (FES and FLIO): low water activity (0.984, 0.370, 0.387 g/100 g), moisture (64.52, 5.37, 7.97 g /100 g), ash (2.69, 6.51, and 6.89 g/100 g), pH (0.89, 4.45, 4.48 g/100 g), lipids (0.84, 1.67, 5.23 g/100 g), protein (3.29, 8.23, 14.12 g/100 g), carbohydrates (17.02, 53.12, 33.02 g/100 g), ascorbic acid (19.70, 34.20, 36.90 mg/100 g). Sources of fiber from plant leaves and flours (11.64, 25.1, 32.89 g/100 g) showed increased levels of luminosity. For NMR, the presence of aliphatic and aromatic compounds with olefinic hydrogens and a derivative of gallic acid were detected. The most abundant minerals detected were potassium and calcium. Micrographs identified the presence of irregular, non-uniform, and sponge-like particles. The main sugars detected were: fructose, glucose, and maltose. Malic, succinic, citric, lactic, and formic acids were found. Fifteen phenolic compounds were identified in the samples, highlighting: kaempferol, catechin, and caffeic acid. The values ​​found for phenolics were (447, 716.66, 493.31 mg EAG/100 g), flavonoids (267.60, 267.60, 286.26 EC/100 g). Antioxidant activity was higher using the ABTS method rather than FRAP for analysis of FOin, FES, and FLIO. Since the flours of the aroeira leaf have an abundant matrix of nutrients with bioactive properties and antioxidant activity, they have a potential for technological and functional use when added to food.

Moisture sorption isotherms characteristics for shelf-life prediction of peanuts (Arachis Hypogaea L.)

BACKGROUND

The spring grown peanut varieties J87 and TG37A are prone to quality deterioration as a result of high temperature and relative humidity during harvesting. Thus, the sorption isotherms of peanut varieties were evaluated at 25, 35 and 45 °C and the water activity (a_w ) range of 0.110-0.975 aiming to predict the suitable storage conditions, packaging material and shelf-life.

RESULTS

The equilibrium moisture content (EMC) increased with increased a_w and isotherms of type II were observed. The monolayer moisture content varied between 3.135% and 4.235% for J87 and between 3.906% and 5.640% for TG37A variety. The experimental data were fitted to seven mathematical models. The variations in correlation coefficients were in the range 0.879-0.992 and in root mean square were in the range 0.055-1.988. On the basis of statistical parameters, Guggenheim Anderson de Boer and Double Log Polynomial were considered to be best fitted models. At a_w of 0.6, critical moisture content (CMC) was 7.59%, 7.060% and 5.89% for J87 and 9.06%, 8.904% and 7.80% for TG37A at 25, 35 and 45 °C, respectively. The shelf-life prediction model provided that the aluminum packages had the maximum predicted shelf-life of around 1779 days for TG37A and 1077 days for J87 variety at 25 °C with an initial moisture content of 5.91% and 4.81%, respectively.

CONCLUSION

The EMC and CMC evaluated from sorption study provided the basis for determination of package properties and shelf life. Aluminum packages had the minimum water vapor transmission rate and permeability. Hence, peanuts packaged in these bags and stored at 25 °C and 75% relative humidity had the potential to attain the maximum storage life. © 2023 Society of Chemical Industry.

Application of Dynamic Temperature-Humidity Chamber for Measuring Moisture Sorption Isotherms of Biomaterials as Compared to the Conventional Isopiestic Method

Measurement of water activity and moisture sorption isotherms of foods and biomaterials are important to determine the state of water. In this work, a dynamic temperature-humidity (DTH) controlled chamber was used to measure water sorption isotherm and compared with the conventional isopiestic method. Temperature and relative humidity of DTH chamber can be controlled in the range of -15 to 100°C and 0 to 98%, respectively; thus, measurement of water activity at any point can be measured within the above ranges. The DTH chamber method showed high reproducibility as compared with the conventional isopiestic method when measured isotherms of cellulose, lignin, and hemicellulase were compared at 30°C. Finally, isotherm data of cellulose, lignin, and hemicellulase were generated in the temperature range of 10-90°C using DTH chamber, and these were modelled by BET and GAB equations. The model parameters were correlated with the temperature.