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Summary: Burdekin plums (BP) are the fruits of Pleiogynium timoriense (DC.) Leenh, a tree native to Australia. In this study, BP fruit leathers were developed by blending BP puree with apple puree (0%–80% levels) to make five formulations of BP fruit leathers (100BP, 80BP, 60BP, 40BP, 20BP). Physicochemical parameters and microbial stability of fruit leathers were studied during six‐month storage at ambient conditions (temperature 16–25 °C, humidity 60%–77%). Results showed that BP leathers had a water activity from 0.60 to 0.64 and moisture content from 21% to 25%, and both were stable during storage. 20BP had the highest score for all colour parameters measured and had the lowest value in hardness. Reduction in redness and chroma and an increase in hue were observed in all leathers after storage. The total content of cyanidin 3‐galactoside and cyanidin 3‐glucoside decreased from 400–1600 mg/kg DW to 100–500 mg/kg DW after processing into leathers then to 9–70 mg/kg DW after storage. A decrease in catechins was also observed after puree was processed into leather and after the 6 months of storage, whereas an increase in gallic acid, ellagic acid, quercetin 3‐glucoside, trigalloylglucose was observed particularly in 20BP. Total phenolic content (ranging from 6 to 24 mg GAE/g DW) and antioxidant capacity (ranging from 80 to 240 μmol Fe2+/g DW) remained relatively stable after processing and storage with a slight reduction in 80BP and 100BP. Fruit leathers were microbiologically safe and shelf‐stable during the 6 months of storage. These results demonstrated the potential of BP to be processed into shelf‐stable fruit leathers rich in bioactive phenolics. [ABSTRACT FROM AUTHOR]

Pleiogynium timoriense, commonly known as Burdekin plum (BP), is among many Australian native plants traditionally used by Indigenous people. However, only limited information is available on the nutritional and sensory quality of BP grown in Australia as well as its changes during storage. Therefore, this study evaluated the quality of BP during one week of ambient storage (temperature 21 °C, humidity 69%). Proximate analysis revealed a relatively high dietary fiber content in BP (7–10 g/100 g FW). A significant reduction in fruit weight and firmness (15–30% and 60–90%, respectively) with distinguishable changes in flesh color (ΔE > 3) and an increase in total soluble solids (from 11 to 21 °Brix) could be observed during storage. The vitamin C and folate contents in BP ranged from 29 to 59 mg/100g FW and 0.3 to 5.9 μg/100g FW, respectively, after harvesting. A total phenolic content of up to 20 mg GAE/g FW and ferric reducing antioxidant power of up to 400 μmol Fe2+/g FW in BP indicate a strong antioxidant capacity. In total, 34 individual phenolic compounds were tentatively identified in BP including cyanidin 3-galactoside, ellagic acid and gallotannins as the main phenolics. Principle component analysis (PCA) of the quantified phenolics indicated that tree to tree variation had a bigger impact on the phenolic composition of BP than ambient storage. Sensory evaluation also revealed the diversity in aroma, appearance, texture, flavor and aftertaste of BP. The results of this study provide crucial information for consumers, growers and food processors. [ABSTRACT FROM AUTHOR]

Many confectionary items and food components are based on complex suspensions of hydrophilic sugar particles in a hydrophobic fat phase. We hypothesise that the rheology of these suspensions is defined by either the Maron-Pierce-Quemada (MPQ) model, which theoretically predicts the viscosity of hard spheres, or by the percolation model describing a network of attractive particles (gel). The rheology of two sugar-fat mixtures, sugar-shortening based biscuit-creams and chocolate, are characterised as a function of phase volume, particle size distribution (PSD) and emulsifier concentration. It is found that their rheological behaviour shows the formation of a network gel structure at sufficient concentration of sugar particles. We find that, upon addition of sufficient emulsifier, the suspension viscosity follows the MPQ hard sphere model, which only depends on phase volume and particle size distribution. Combining the use of the theoretical model and emulsifiers, we are able to decouple the effects of phase volume and particle size distribution from that of particle interactions. The results provide a theoretical basis for identifying levers to control the rheological behaviour of molten chocolate, biscuit-creams, and other sugar-fat based systems, which is relevant to food processing and sensory perception during consumption. • Particle phase volume, size distribution & interactions drive sugar-fat suspension viscosity. • Chocolates and biscuit-creams can be modelled as particles suspended in a continuous phase. • Sugar-fat suspensions with excess emulsifier follow the MPQ-rcp hard sphere viscosity model. • The theoretical MPQ-rcp model is applicable to complex food-relevant suspensions. [ABSTRACT FROM AUTHOR]