Quality and Stability Equivalence of High Pressure and/or Thermal Treatments in Peach–Strawberry Puree. A Multicriteria Study

A bottom-up approach identifying equivalent effects of high-pressure processing (HPP—600 MPa, 20 °C, 10 min), thermal treatment (TT—70 °C, 15 min) and high pressure-mild thermal processing (HPMT—600 MPa, 50 °C, 10 min) on quality and stability of peach–strawberry puree was applied during refrigerated storage. TT and HPP ensured 3-log aerobic bacteria inactivation at first, while HPMT reduction was below the detection limit. After 21 days all samples had equivalent microbiological stability. A 2.6-fold increase in the residual activity of PPO and POD was found in the HPP sample compared to TT and HPMT samples (1st day); after 21 days PPO, POD and TPC were equivalent for TT and HPP peach–strawberry purees. Equivalent volatile profile and rheology behavior was observed after 21 days of all samples’ storage. Meanwhile, the color of the HPP, TT and HMPT samples remained significantly different (p < 0.05) throughout the whole storage period, with the lowest browning index registered for HPP samples

Efficacy of Two Stabilizers in Nanoemulsions with Whey Proteins and Thyme Essential Oil as Edible Coatings for Zucchini

Edible coatings are important for horticulture crops preservation and reducing food waste. Application of edible coatings followed by low-temperature storage prolongs the storability, preserves quality, and decreases the overall postharvest losses. This study evaluated the efficacy of two nanoemulsions formulae containing thyme essential oil and whey proteins as coatings for zucchini, with the purpose of extending their shelf-life. The nanoemulsions were rheologically evaluated and the formula with guar and arabic gum mix stabilizer (S) showed a better capacity to restructure after strain compared to the formulae with Tween 20 (T). The S coating material had a better capacity to integrate nanoparticles compared to T. However, when applied on zucchini, T coating was more effective in reducing weight loss showing 16% weight loss compared to 21% in S, after 42 days. At the end of storage at 10 °C, the T-coated zucchini had better firmness (p < 0.05) compared with S and both coatings were superior to control (p < 0.05). POD (peroxidase) activity was high in peel at the end of storage when also CAT (catalase) showed a sudden increase. On the 42nd day of storage, the highest enzymes activity (CAT, POD, and APX (ascorbate peroxidase)) was present in the S-coated zucchini peel. The most abundant volatile in T coating was α-pinene and 4-carene in S. Sensory analysis showed that T coating delayed the appearance of senescence while S exhibited surface cracks

Mechanism of β–cyclodextrin - thyme nanocomplex formation and release: In silico behavior, structural and functional properties

Nanoencapsulation of thyme essential oil (TEO) volatiles into β-cyclodextrin (β-CD) and their release requires in-depth kinetic, structural and in silico studies for elucidating the mechanisms for attaining the equilibrium state. Monoclinic crystalline structures of β-CD/TEO with 5 –10 μm were formed by TEO encapsulation and visualized using SEM. The β-CD:TEO 8.5:1.5 (w/w) ratio ensures 71.66% TEO retention efficiency and a cumulative release in hexane after 7 h of 75%. Thymol molecule is the favourite candidate to occupy the inner cavity of β-CD, although competition by carvacrol, o-cymene, 2-carene and camphene against thymol was noticed by GC/MS when increasing the TEO concentration. The molecular mechanics calculations suggested that binding of thymol, carvacrol and o- cymene within the hydrophobic cavity of β-CD is thermodynamically achievable, having complexation energy between -18.48 ÷ -22.07 kcal/mol, nonetheless the most stable complex is formed with α- pinene, if energy input is provided, displaying the lowest complexation energy, -25.89 kcal/mol. All inclusion complex (IC) powders had similar antiradical activity against DPPH (40 - 43%). The IC2 β-CD/TEO 8.5:3.00 (w/w) powder displayed antibacterial activity against Bacillus cereus, while IC3 β-CD:TEO 8.5:1.50 (w/w) exhibited the strongest antifungal activity of all powders against Geotrichum candidum and Rhodotorula glutinis. The ICs obtained suggest a competitive mechanism of TEO components in occupying the β-CD inner cavity that predispose each powder formulae for specific applications in food in relation with their functional properties