Costas Stathopoulos

The Australian native foods, despite high phytochemical composition, are severely underutilized in research and on the commercial market. One of these plants is the Davidson plum (Davidsonia jerseyana), a nutrient-dense and sustainable food ingredient. The study aimed to develop functional fruit sorbets incorporating freeze-dried Davidson plum powder (0–20% w/w) and evaluate their physicochemical, antioxidant, and sensory properties. Sorbets were created using strawberry, raspberry, pomegranate, and Davidson plum bases and analyzed for nutritional content, color, melting rate, texture, and antioxidant capacity (Total Phenolic Content (TPC), Total Flavonoid Content (TFC), Ferric Reducing Antioxidant Power (FRAP), Cupric Reducing Antioxidant Capacity (CUPRAC), 2,2-Diphenyl-1-picrylhydrazyl (Radical Scavenging Assay (DPPH)), total proanthocyanin and anthocyanin content. Sensory evaluation was also conducted using a semi-trained panel. The results showed that increasing Davidson plum concentration led to higher antioxidant activity and slower melting rates. Sorbets containing 10% and 15% Davidson plum demonstrated the highest levels of phenolic and flavonoid compounds. However, sensory analysis indicated that sorbets with 5% and 10% Davidson plum, particularly those made with a strawberry base were the most acceptable in terms of flavour, texture, and overall appeal. These findings suggest that incorporating Davidson plum into frozen desserts, especially at lower concentrations, can enhance both the functional and sensory qualities of sorbets while offering potential health benefits.

In this study, date seed polyphenols were incorporated in biscuits in the forms of conjugates (DSPC) and encapsulates (DSPE). Date seed polyphenol conjugates were prepared with soy protein isolate (SPI) in ratios of 1% SPI solution: polyphenolic extract; 1:20, 1:30, 1:40, and 1:50 (wt:wt). Date seed polyphenol encapsulates were prepared using gum arabic (GA) in ratios of 0.5%, 1%, 1.5%, and 2% (wt/vol). Bioactive properties, in vitro digestion of polyphenols and physical properties of fortified biscuits were analysed. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis and spectroscopic data confirmed the conjugation of date seed polyphenols with SPI along with the quenching of tryptophan fluorescence. Soy protein isolate:polyphenolic extract ratio of 1:40 exhibited the highest polyphenol binding capacity of 53.53%. Encapsulate with 1.5% (wt/vol) GA showed the highest encapsulation efficiency of 62.28% and antioxidant activity increased with increasing GA proportion in encapsulates. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 1.02 mmol trolox equivalents (TE)/g biscuit was observed in 1.5% (wt/vol) DSPE while the highest ferric reducing antioxidant power of 2.75 μmol TE/g biscuit was observed in the DSPC at a ratio of 1:50. Total phenolic content (TPC) of biscuit increased upon incorporation of DSPC and DSPE. The highest TPC of 1.27 mg GAE/g biscuit, after in vitro gastrointestinal digestion, was found in 2% (wt/vol) DSPE. No significant difference (p > .05) was found in colour of biscuit with fortification of DSPC and DSPE whereas the hardness and the fracturability increased, and the highest values were found in 1.5% (wt/vol) DSPE. Overall, DSPC and DSPE showed promising results in protecting date seed polyphenols during biscuit preparation and in vitro digestion.

This study investigated the effectiveness of bioactive films fabricated using chitosan (Cs) reinforced with cellulose nanocrystals (CNC) and polyphenolic components extracted using natural deep eutectic solvents (NADES), both derived from date seeds. The CsCNC films with NADES-extracted date seed polyphenols (DSP) showed significant antimicrobial activity against Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli. Total phenolic content (0.01 to 0.20 mg GAE/mL), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (0.10 to 3.22 mmol TE/mL), and ferric-ion reducing antioxidant power (0.49 to 3.31 μmol TE/mL) improved significantly...

Functional biscuit was formulated by fortifying them with polyphenolic extract and fiber-rich residue of defatted date seed powder (DDSP) obtained through microwave-assisted extraction. Effect of particle size (small, medium, and large) and substitution level (2.5%, 5%, and 7.5%) of fiber-rich residue, along with the phenolic extract, on bioactive, physical, textural, and gastrointestinal digestion of fortified biscuits was studied followed by sensory and shelf-life studies. The total phenolic content (TPC) and antioxidant properties of biscuits increased with increasing substitution levels and particle size. DDSP residue fortification increased the fiber content in biscuits. Large particles of the residue-fortified biscuits showed significantly higher (p < 0.05) hardness compared to the control biscuits. Diameter of the biscuits decreased with increasing substitution level and particle size of fiber-rich residue with the lowest value of 50.66 mm in 7.5% substitution of large particles. The 7.5% substitution level of small particles resulted in the lowest spread ratio of 8.97 and the highest thickness of 5.79 mm. Consumer perceptions were at an acceptable level after the fortification, with an average sensory score of 6.02 out of 9 for overall acceptability. After 24 weeks storage, TPC decreased in biscuits, but TPC retention increased with increasing substitution level and particle size of residue. Thiobarbituric acid reactive substances (TBARS) value of biscuits increased with storage. The highest phenolic recovery was observed in the intestinal phase of the gastrointestinal digestion with the highest recovery of 102.33 at 2.5% level of large particles. Thus, phenolic extract and fiber-rich residue incorporation was effective to enhance the nutritional and functional properties of biscuits.

Date seeds are the major byproduct of the date palm industry, posing both environmental and economic concerns. Therefore, this study aimed to valorize date seeds through alkali-assisted extraction for stabilizing bioactive-rich oil-in-water emulsions. Using an I-optimal design, the effects of pH (7-11), temperature (30-50 degrees C), date seed concentration (DSC) (5-25%), and extraction time (30-150 min) on total polyphenol content (TPC) and the Sauter mean droplet diameter (D[3,2]) of emulsions were optimized. Results showed that alkali-assisted extraction significantly increased the TPC and minimized D[3,2], with the optimal conditions being pH 8.5, 50 degrees C, 5% DSC, and 30 min extraction time. At these conditions, submicron emulsions were achieved, which were highly stable at mildly acidic pH (6-7) over 3 weeks but exhibited reduced stability at lower pH (<6) and increasing salt concentrations. These findings demonstrate that date seeds are a promising, sustainable resource for natural emulsifiers, capable of stabilizing emulsions with extended shelf life.

Functional biscuit was formulated by fortifying them with polyphenolic extract and fiber-rich residue of defatted date seed powder (DDSP) obtained through microwave-assisted extraction. Effect of particle size (small, medium, and large) and substitution level (2.5%, 5%, and 7.5%) of fiber-rich residue, along with the phenolic extract, on bioactive, physical, textural, and gastrointestinal digestion of fortified biscuits was studied followed by sensory and shelf-life studies. The total phenolic content (TPC) and antioxidant properties of biscuits increased with increasing substitution levels and particle size. DDSP residue fortification increased the fiber content in biscuits. Large particles of the residue-fortified biscuits showed significantly higher (p < 0.05) hardness compared to the control biscuits. Diameter of the biscuits decreased with increasing substitution level and particle size of fiber-rich residue with the lowest value of 50.66 mm in 7.5% substitution of large particles. The 7.5% substitution level of small particles resulted in the lowest spread ratio of 8.97 and the highest thickness of 5.79 mm. Consumer perceptions were at an acceptable level after the fortification, with an average sensory score of 6.02 out of 9 for overall acceptability. After 24 weeks storage, TPC decreased in biscuits, but TPC retention increased with increasing substitution level and particle size of residue. Thiobarbituric acid reactive substances (TBARS) value of biscuits increased with storage. The highest phenolic recovery was observed in the intestinal phase of the gastrointestinal digestion with the highest recovery of 102.33 at 2.5% level of large particles. Thus, phenolic extract and fiber-rich residue incorporation was effective to enhance the nutritional and functional properties of biscuits.

Aligning with sustainable food system development, in this study, date seeds were utilized to formulate value-added biscuits. Ultrasound-assisted extraction (UAE) was employed as a non-thermal method to extract polyphenolic compounds from small, medium and large particles of defatted date seed powder (DDSP). The remaining fiber-rich fraction (residue) was further utilized. Water content in biscuit formulation was replaced by the extract, and the fiber-rich fraction was substituted at three substitution levels; 2.5 %, 5 % and 7.5 %. Effects of baking on bioactive properties of dough, nutrient composition, sensory analysis, bioaccessibility of polyphenols, and shelf-life of biscuits were analyzed. Total phenolic content (TPC) increased in dough and biscuit with incorporated fiber-rich fraction. TPC of dough decreased with increasing particle size of fiber-rich fraction while biscuits exhibited an opposite trend. Similar tendency was observed with antioxidant activity of dough and biscuit. TPC was higher in biscuits than dough, with the highest values of 0.46 mg gallic acid equivalents (GAE)/g and 2.26 mg GAE/g in dough and biscuit, respectively. Fiber and moisture contents in biscuits increased while protein content decreased with fortification. Consumers showed moderate acceptance of fortified biscuits. Bioaccessibility index of polyphenols upon gastrointestinal digestion was high in biscuits with 5 % and 7.5 % substitution of small and medium sized particles of fiber-rich fraction. Phenolic retention increased with fiber fortification and at the end of 6 months the lowest thiobarbituric acid reactive substances (TBARS) value of 18.23 nmol malondialdehyde (MDA)/g sample, was observed in 7.5 % large particle substituted biscuit. Thus, utilizing date seeds in the form of green extracted polyphenols and fiber-rich fraction, as functional and bioactive ingredients highlight sustainable processing and utilization of date-fruit processing by-products.
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