Lijuan Zhan

Fresh baby leaves are commercially marketed in various mixing ratios and packaging amounts, creating very distinct microenvironmental conditions that significantly affect the postharvest quality of the fresh product. This study investigated the synergistic effect of mixing ratio (50LB, 50% lettuce + 50% spinach; 75LB, 75% lettuce + 25% spinach; 100LB, 100% lettuce) and packaging amount (125F, 125 g; 250F, 250 g) on the antioxidant qualities of baby lettuce and spinach mixes during 9 days of storage at 4 °C. The results showed that 50LB × 250F inhibited the degradation of chlorophyll and carotenoids and preserved 28% higher total antioxidant capacity (TAC), 43% higher total phenolic compounds (TPC), and 20% higher vitamin C (Vit.C) than the mean values of all samples, resulting in 0.8% lower O₂ and 14.7% higher CO₂ levels at the end of storage. TPC, Vit.C, and carotenoids were the main contributors to TAC, with strong correlations (p < 0.001). The total bacterial (TB) and yeast + mold (Y + M) counts were only affected by the mixing ratios, with TB increasing by only 1 Log₁₀ cfu g⁻¹ FW, and Y + M remaining within the same order of magnitude over time. After 9 days of storage, the leaves were still fresh and marketable. This study not only provides a practical strategy for the fresh-cut industry to enhance product quality but also underscores the significance of multifactorial synergism in salad mix packaging.

Ultraviolet-A light-emitting diode (UVA-LED) irradiation is an emerging technology for biofortifying plants with enhanced nutraceuticals. This study firstly investigated effects of various doses (0-control, 16, 32, 48 J/cm²) on Chinese cabbage microgreens (CCM) quality, identifying 32 J/cm² as the suitable dose for improving total antioxidant capacity (TAC) of CCM. Based on this dosage, the following two irradiation patterns were compared: single irradiation (SI, single pulse of 32 J/cm²) and fractionated irradiation (FI; four pulses of 8 J/cm² each). Both FI and SI significantly enhanced CCM quality, though through distinct mechanisms. FI effectively promoted accumulation of biomass and vitamin C, with increases by 9.25% and 13.20%, respectively. Meanwhile, SI markedly enhanced 20.90% higher TAC than FI. This was achieved by elevating enzymatic (7.71% superoxide dismutase-SOD, 9.03% peroxidase-POD, 40% catalase-CAT, and 52.17% ascorbate peroxidase-APX) and non-enzymatic (18.89% total phenolics-TPC, 10.04% total flavonoids-TF, and 18.99% carotenoids) antioxidants. Additionally, both FI and SI significantly reduced the nitrate content. To our knowledge, this is the first study to demonstrate the effect of UVA-LED irradiation pattern on microgreens quality. These findings provide basic information for UVA-LED application in indoor agriculture and the food industry, emphasizing the importance of strategically selecting irradiation patterns to achieve specific production goals.

Summary: Low‐field nuclear magnetic resonance (LF‐NMR) was employed to investigate changes in mobility as well as distribution of water in yam slices in the course of hot‐air drying (HAD) and microwave drying (MD) processes. Moisture content, effective moisture diffusivity, and water activity were also analysed. According to the results, a total of three water fractions with various T₂ relaxation times were observed in fresh yam slices: T₂₁ (0.9–2.6 ms), T₂₂ (30–130 ms), and T₂₃ (130–1245 ms). With the increment in drying temperature and the rise of microwave power in the course of drying, there was a significant decline in the transverse relaxation time and peak amplitude of T₂₃. The overall moisture content exhibited a good correlation with A_total during both HAD and MD processes, with coefficients equivalent to 0.9194 and 0.9024, respectively. With rising drying temperature and microwave power, there was a corresponding rise in effective moisture diffusivity. In comparison with HAD, the rate of water diffusion and evaporation in yam slices dried by MD was higher. Taking into account the drying efficiency and moisture state, MD was suggested as a preferable drying technology for dehydrating yam slices.

Different types of baby leaf vegetables (BLV) are often mixed and packaged as salad mixes. This work has evaluated the effects of BLV mixing ratios (100% lettuce ‘Lollo Bionda’, 100 LB; 75% lettuce + 25% rocket, 75 LB; 50% lettuce + 50% rocket, 50 LB) and the weight filling amount (125 g filling amount, 125F; 250 g, 250F) on the antioxidant properties and browning potential (BP) of lettuce and rocket baby leaves during storage for 9 days at 4 °C in the dark. The samples were packaged in thermos-sealed bags previously prepared using polypropylene film. The results showed that the 50 LB mix had preserved high amounts of chlorophylls and internal nutrients on d9, regardless of the filling amount. No visible browning symptoms were detected in the 50 LB samples. The 50 LB × 125F mix was found to be the most efficient strategy to maintain the antioxidant property of BLV. Thus, the optimisation of the mixing ratio and its combination with an appropriate filling amount could represent an effective postharvest practice.

Summary: Slicing is an abiotic stress during fresh‐cut lotus root slices (FLS) preparation. To evaluate the potential ability of slicing to induce antioxidant capacity (AC) in FLS, fresh lotus roots were sliced into 0.4 cm thick slices and stored at 7 °C for 7 days using intact root segments as control. Results showed slicing induced 68.3% higher phenylalanine ammonia‐lyase (PAL) activity and parallel 130.5% more total phenol (TP) accumulation after 7 days storage compared to control. AC values in FLS assayed by FRAP and ABTS^●+ were 41.5% and 93.8% more than those in control samples at the end of storage, respectively. Such increases in AC values were mainly attributed to TP accumulation as a positive correlation existed between AC and TP. However, slicing significantly accelerated FLS browning by increasing the polyphenol oxidase (PPO) activity during storage. Nevertheless, FLS was still marketable with the maximum browning index of 1.9 after 7 days storage.

Summary: Effects of light exposure (24 μmol m⁻² s⁻¹) on fresh‐cut celery nutritional quality were evaluated during 8‐day storage at 7 °C using darkness as control. Light exposure preserved 47% chlorophyll a and 48% chlorophyll b contents more than darkness at the end of storage. Sucrose, reducing sugar and glucose contents in light‐stored petioles were 17%, 25% and 67% higher than those in dark‐stored petioles after 8‐day storage, respectively, thus resulting in higher total soluble solids content in light condition. Moreover, l‐ascorbic acid content increased at 2‐day storage in light condition and was 46% more than in darkness at the end of storage. The fresh weight loss significantly increased in all petioles, and this increase was markedly accelerated by light exposure with a maximum of 1.43% at the end of storage. Dry matter content was induced more by light exposure than by darkness at 2‐day storage.