Effects of maltodextrin on physicochemical properties of freeze-dried avocado powder

The effect of maltodextrin on the moisture sorption isotherm, glass transition temperature (Tg), and degree of caking of freeze-dried avocado samples at room temperature (25°C) was investigated. The incorporation of maltodextrin reduced the water sorption capacity of the powder due to its less hygroscopic nature. Parameters derived from the Guggenheim, Anderson, and de Boer (GAB) model describing the properties of absorbed water are discussed. The water absorption isotherm possessed the characteristic sigmoid-shaped type II isotherm curves and the model gave the best fit over the whole range of aw tested. The differential scanning calorimetric method was used to measure the Tg of freeze-dried avocado samples. Increasing the water content decreased the Tg, and Tg was increased with increasing maltodextrin content. Increased maltodextrin content to solid material in the freeze-dried sample was associated with less sensitivity to caking as evidenced by Tg values. In addition, increased maltodextrin content in the powders caused brighter, less yellowish, and more greenish coloration and protected color change including browning index. The antioxidant capacity was significantly decreased with increasing maltodextrin content. Thus, the effect of maltodextrin concentration on physicochemical properties was a promising way to preserve the physical property and chemical compounds in freezedried avocado powder.

Determination and modelling moisture sorption isotherms of dehydrated butterfly-pea (Clitoria ternatea L.) flower powder

Butterfly-pea flower (Clitoria ternatea L.) is one of the edible flowers that is widely processed into dried flowers or powder form. Processed butterfly-pea flower is mostly used as a food colorant or flavonoid and anthocyanin-rich teas which are naturally present in the flower. Some polyphenolic acid, i.e., gallic acid, protocratic acid, and chlorogenic acid are also contained in this flower. During the storage period, color degradation occurs which will reduce the quality of the powder. Therefore, a study on the determination of moisture sorption isotherm from butterfly-pea powder is necessary information to maintain the quality of this product for a longer storage period. The objectives of this research are to evaluate the behavior of moisture sorption isotherm, construct its mathematical modelling and analyze the color changes at different temperatures and aw. 60 mesh of butterfly-pea powder with 28% initial moisture content (db) was stored at aw 0.3 – 0.9 (in a saturated salt solution containing MgCl2, K2CO3, NaC1, KC1, and BaCl2) at 30, 40, and 50°C by static gravimetric method. The results showed that based on the Brunauer classification, the behavior of moisture sorption isotherm of dehydrated butterfly-pea powder is in accordance with the Type II-sigmoid curve, while the Peleg model is the best model in predicting the moisture sorption isotherm. Recommended storage conditions for butterfly-pea flower powder are at 30°C with equilibrium moisture content at 23-30% (db). During storage powder color turns darker over the entire aw range with a color index of L* (lightness, 9.97); a* (redness, 2.33); b* (yellowness, -5.56).

Effect of Emulsifier Diacetyl Tartaric Acid Ester of Mono- and Diglycerides (DATEM) and Enzyme Transglutaminase on Quality Characteristics of Rice Bran Croissants

Rice bran (RB) is a good source of dietary fibre. Addition of rice bran into croissant interferes with the gluten formation of dough and hence affect the physicochemical properties of croissant. The effect of RB addition on physicochemical properties of croissant were determined by using 0%, 10% and 15% RB. Besides, additives such as emulsifiers and enzymes can be used in pastry to enhance the physicochemical properties of croissant. Diacetyl tartaric acid ester of mono-diglycerides (DATEM) and transglutaminase (TGase) were used respectively on 0%, 10% and 15% RB to investigate the effect of such additives on physicochemical properties of croissant. Increased % RB and DATEM, produced a significant decrease in specific volume, together with a significant increase in colour, hardness and chewiness. With increased % RB, TGase caused significant increase in colour, hardness and chewiness but significant decrease in specic volume. The overall moisture sorption isotherm curves of the croissant belong to the Type III isotherm, also known as Flory-Huggins Isotherm (J-shaped). The critical aw obtained from the Guggenheim-Anderson-de Boer (GAB) equation showed that the shelf life of croissants were not positively impacted by the addition of DATEM and TGase and the addition of RB did not cause any significant positive effects on quality characteristics of croissants.

Development of powder based ginger drink: analysis of dehydration kinetics and moisture sorption isotherm

The perishable herb ginger (Zingiber officinale) possesses natural aroma and different biologically active components which are beneficial for our health. This can be dried for preservation in pick season for shelf-life increment. This study studied the analysis of the chemical composition, moisture sorption isotherm, dehydration kinetics of ginger for preservation. Air drying was carried out using a cabinet dryer at different temperatures and thickness. According to the sorption isotherm study, monolayer moisture content (MMC) is higher as per Guggenheim-Anderson-DeBoer (GAB) equation compared to the Brunauer-Emmett-Teller (BET) equation. Drying rate increased with the increase in temperature at constant thickness while the adverse result was found with the increase in thickness at a constant temperature. Then, powder-based drinks were prepared by using five different percentages of ginger. The preferences of consumers were measured by statistical analysis of the scores obtained from the response of organoleptic taste panel. The sample containing 1.84% ginger powder was considered the best in overall acceptability

The Effect of Freeze-Drying on the Properties of Polish Vegetable Soups

The aim of this study was to investigate selected physical and biochemical properties of four vegetable freeze-dried soups. The water content, water activity, pH, color parameters, antioxidant activity (EC50), total polyphenolic content of fresh tomato, pumpkin, beetroot, and cucumber, and freeze-dried soups were measured. Sensory analysis was applied to compare sensory attributes of fresh and rehydrated soups. The sorption isotherms of freeze-dried soups were obtained with the application of the static and dynamic vapor sorption (DVS) method. The application of the freeze-drying method enabled the obtaining of dry soups with a low water content of 2–3%. The drying caused a significant change of color of all soups. The redness of soups decreased after drying for the beetroot soups from +39.64 to +21.91. The lower chroma value of 25.98 and the highest total color change ΔE*ab = 36.74 were noted for freeze-dried beetroot soup. The antioxidation activity and total polyphenolic content were reduced after drying, especially for the cucumber and tomato soups. The Peleg model was selected to describe the sorption isotherms of dried soups. The sorption isotherm of freeze-dried cucumber and beetroot soups had a sigmoidal shape of type II. The shape of the moisture sorption isotherm for freeze-dried tomato and pumpkin soups corresponded more with type III isotherms. The DVS method can be used to characterize the moisture sorption isotherms of freeze-dried products.