Daniela Salvatori

Physical and Functional Properties of Blackberry Freeze- and Spray-Dried Powders

The aim of the present work was to develop two products from blackberry juice by freeze and spray drying with potential use as food colorants or healthy ingredients. A characterization of the physical and functional properties of the powdered juices was done. Maltodextrin or a mixture of trehalose and maltodextrin were assessed as carrier matrices. Freeze-dried, maltodextrin-containing powders presented the best retention of bioactive compounds and antiradical activity; however, they showed a narrow relative humidity range for storage in the glassy state. Spray-dried powders showed better physical properties, bearing higher glass transition temperature and lower molecular mobility than freeze-dried formulations.

Color and Bioactive Compounds Characteristics on Dehydrated Sweet Cherry Products

It is widely known that quality properties of fruits can be affected by drying processes. The approach was the quality improvement of dried cherry products through the application of combined technologies of drying and pretreatments. The objective of this work was to analyze the effect of blanching or sugar infusion prior to air-drying or freeze-drying on quality properties such as color, bioactive compounds, and antiradical power of two cherry products (discs and dices). Air-drying caused darkening, whereas freeze-drying provoked higher lightness of discs compared to fresh fruit (p < 0.05). Cherry dices were lighter than the fresh fruit. A high retention of total anthocyanin (ACY) and phenolic content (TPC) was obtained in blanched freeze-dried discs (ACY = 165 ± 22 mg Cyd-3-glu/100 g d.w.; TPC = 739 ± 55 mg GAE/100 g d.w.). Sugar infusion pretreatment caused an important decrease in ACY (31–89 mg Cyd-3-glu/100 g d.w.) and TPC (222–271 mg GAE/100 g d.w.). When blanching was applied prior to air-drying, samples presented the highest antiradical power, similar to that observed in fresh fruit. In dices, the best quality attributes in terms of superficial color were found in control freeze-dried samples since they presented minor shifts in hue angle and a greater preservation of anthocyanin pigments (ACY = 211 ± 30 mg Cyd-3-glu/100 g d.w.). However, control air-dried dices presented the highest phenolic content (TPC = 771 ± 65 mg GAE/100 g d.w.). Regarding the possible application of the dry cherry products, discs could be directly consumed as snacks, while dices could be incorporated as ingredients in fruit bars, cookies, or muffins.

Osmotic Dehydrated Raspberries: Changes in Physical Aspects and Bioactive Compounds

Raspberries are very labile fruits that have a short postharvest life; therefore, there is a need to develop alternative storage and processing methods for extending their shelf-life. The effect of wet (WI) and dry (DI) sucrose infusions (aw = 0.85) on color and bioactive compounds of raspberries has been studied. Additives were included: citric acid, sodium bisulfite, or both. Moisture content decreased from 85% (w/w) for control fruit to approximately 51% (w/w) for infused samples. The shrinkage of fruits was approximately 27% and 46% after WI and DI, respectively. No major color changes occurred, except for WI-bisulfite treatment. Although the total polyphenols and anthocyanin content were significantly reduced in fruits during osmotic dehydration, mainly due to the dilution effect to the medium, 100 g serving of processed raspberries would supply, in some cases, over 50% of polyphenols provided by a glass of wine. The proposed infusion dehydration methods may be considered an alternative to produce shelf-stable products based on raspberries, with an improved quality in terms of appearance.

Physical and functional properties of spray-dried powders from blackcurrant juice and extracts obtained from the waste of juice processing

Blackcurrants contain high levels of polyphenolics, particularly flavonols and anthocyanins, which contribute to their high antioxidant activity. The aims of this work were the recovery of bioactive compounds from the remaining solid (waste) after processing blackcurrant juice and to obtain spray-dried powders from the blackcurrant juice and extracts. The extraction of bioactive compounds from the fruit pulp was performed by ultrasound-assisted extraction. Experiments were conducted to select the more suitable solvent, and citric acid was chosen. Then, to optimize the extraction conditions (time, solvent concentration, and amplitude) an experimental design using a Box–Behnken Design was done. Comparing the optimized extract with the fruit, 31% total monomeric anthocyanins, 19% total phenolic compounds, and 10% antioxidant capacity were obtained. The optimized extract and the juice were mixed and spray dried, using maltodextrin as carrier matrix. A blackcurrant powder with low hygroscopicity 14.46 ± 0.13 (g a.w./100 g d.m) and high solubility 94.25 ± 4% was obtained. High concentration of bioactive compounds and antioxidant capacity was recorded: Total monomeric anthocyanins 63.01 ± 1 (mg cyn-3-glu/100 g.d.m), total phenolic content 116.87 ± 5 (mg gallic acid/100 g d.m.), and antioxidant capacity 144.40 ± 0.11 (mg eq Trolox/100 g.d.m.).

Valorization of postharvest sweet cherry discard for the development of dehydrated fruit ingredients: compositional, physical, and mechanical properties: Valorization of postharvest sweet cherry discard for the development of dehydrated fruit ingredients

BACKGROUND Sweet cherries are an excellent source of phenolic compounds, which may contribute to a healthy diet. The objective of this work was to generate dehydrated ingredients from postharvest discard of sweet cherries. RESULTS Four dried ingredients were obtained from fresh sweet cherry discard (Lapins var.) using an osmotic dehydration pretreatment and freeze drying or air drying. The ingredients showed an important phenolic contribution (2.8-6.6 g gallic acid kg-1 of product) and preserved the natural color of the fruit to a great extent. Freeze-dried ingredients were less hygroscopic than air-dried ones, and presented with a softer texture. All the ingredients were in a supercooled state at room temperature (Tg range: -23.0 to -18.8 °C). Sugar infusion pretreatment caused a decrease in water sorption capacity and molecular mobility; it also reduced the initial rehydration rate. CONCLUSION Relevant differences in nutritional and structural characteristics of the ingredients were observed depending on the processing method used. These ingredients could be incorporated into different processed foods, such as snacks, cereal mixtures, cereal bars, and bakery and confectionery products. Air-dried control ingredients presented better nutritional qualities and air-dried sweet cherries with sugar infusion pretreatment could be appropriate ingredients for applications where sweet flavor and slow rehydration rate are required.