Structural characterization of oleogels from whey protein aerogel particles.

Oleogels intended as fat substitutes were prepared by oil dispersion of aerogel particles obtained through freeze-drying (FD) or supercritical-CO2-drying (SCD) of whey protein isolate (WPI) hydrogels (20 g/100 g). SEM revealed that freeze-dried particles presented larger dimensions than supercritical-dried ones. The latter also showed higher oil dispersibility, forming aggregates with lower dimension (300 nm) than those formed by freeze-dried particles (700 nm). Both particles presented oil structuring capability. Freeze-dried particles gave a weak oleogel, while supercritical-dried ones gave a strong (G' = 3.1 × 105 Pa) and plastic (critical stress = 723.2 Pa) oleogel, with rheological features comparable to those of traditional fats. These results can be explained based on the lower aggregation induced by SCD and on the higher capacity of supercritical-dried particles to form a network in oil through hydrophilic interactions, as suggested by FTIR. Therefore, WPI aerogel particles show the potentiality to be used as food ingredients to prepare oleogels with tailor-made physical properties.

Optimizing the antioxidant biocompound recovery from peach waste extraction assisted by ultrasounds or microwaves.

The possibility to valorize peach juice waste, either frozen or air-dried, through microwave (MAE) and ultrasound assisted extraction (UAE) was evaluated. MAE power, UAE amplitude and time were optimized using a 22-factorial design. For frozen waste, optimal MAE (540 W, 50 s) and UAE (23%, 120 s) processes gave extracts presenting analogous content (on 100 g dry matter) of polyphenols (309-317 mg GAE), flavonoids (94-120 mg QE), anthocyanins (8-9 mg CGE), and similar antioxidant activity (2.1-2.2 mg TE). Extracts from dried waste resulted higher in polyphenols (630-670 mg GAE) but lower in flavonoids (75-90 mg QE), anthocyanins and vitamin C (not detectable). Although developing an energy density 2-fold higher than that of UAE, MAE more efficaciously extracted vitamin C (108 mg/100 g dm) and required half extraction time (50 s). MAE would also be less impactful than UAE in terms of greenhouse gas emission and energy requirements on industrial scale. The industrial valorization of peach waste through the application of microwave or ultrasound assisted extraction requires quantitative data, able to encourage company interest and investment. This study not only identifies optimal MAE and UAE parameters to assist the extraction of peach waste bioactive compounds but also provides a preliminary estimation of the potential economic and environmental impact on an industrial scale of these technologies.

Effect of temperature in domestic refrigerators on fresh-cut Iceberg salad quality and waste.

The evolution of different quality parameters (firmness, weight loss, colour changes, microbial counts, consumer rejection) of packed fresh-cut Iceberg salad was assessed at 4, 8 and 12°C to simulate domestic refrigerators running at different conditions. The increase in storage temperature did not affect salad firmness and weight loss but increased colour changes, microbial growth and consumer rejection. A survey among Italian consumers was also carried out and demonstrated that fresh-cut salad was mainly consumed within the first 5days after purchasing. Consumer rejection data were combined with data relevant to the distribution of salad consumption over the days following product purchase, to estimate salad wasting risk. When salad was stored at 4 and 8°C, estimated wasted packages within the expiration date (7days) were <1%. By contrast, 13% of the packages was estimated to be wasted within 7days of storage at 12°C. Quantification of wasting risk is a necessary information to identify efficient and sustainable interventions to tackle food waste.

Shelf life prediction of bread sticks using oxidation indices: a validation study.

The aim of this study was to apply the protocol for the shelf life prediction of bakery products proposed by Calligaris and others (2007a) on bread sticks. The methodology comprises 4 steps: (1) evaluation of the physical properties of fat; (2) performing the accelerated shelf life test; (3) evaluation of sensory acceptance limit and the relevant chemical index limit; (4) setting up the shelf life prediction model. The results allow validating the shelf life prediction methodology proposed. In fact, the peroxide number was found to be a representative index of the quality depletion of bread sticks during their shelf life. In addition, once again by accounting for the changes in the fat physical state, it is possible to set up a modified Arrhenius equation able to describe the temperature dependence of peroxide formation. Finally, a mathematical model to simply and quickly calculate the shelf life of bread sticks has been developed.

Effect of enzymatic and chemical oxidation on the antioxidant capacity of catechin model systems and apple derivatives.

Changes in the chain-breaking activity of catechin model systems and apple derivatives were studied as a consequence of enzymatic and chemical oxidation. Although in different time scales, both enzymatic and chemical oxidations of catechin promoted an initial increase and a following decrease in the chain-breaking activity. The latter was associated with the formation of brown pigments. Similar changes were detected during storage at -18 degrees C of nonoxidized and enzymatically oxidized apple purees. The initial increase in antioxidant activity upon oxidation was attributed to the formation of procyanidins with larger aromatic structure and to synergy effects among them. The formation of tannins, the reactivity of which is sterically hindered, was proposed as a possible explanation for the decrease in antioxidant capacity in the advanced phases of oxidation.