Mechanistic understanding of temperature-driven water and bacterial infiltration during hydrocooling of fresh produce

J Food Process Engineering

Han

Liu

et al. 2021

Chilling injury (CI) is one of the important factors to reduce tropical fruit preservation quality. A low‐temperature electromagnetic preservation system is developed by combining the refrigerated storage technology and electromagnetic biological effect to decrease the CI damage. Based on this system, the experimental study and mechanism analysis of alternating magnetic field inhibiting the CI of bananas are carried out. Experimental results show that compared with the control group (CK), the alternative magnetic field continuous treatment (AMCT, B = 20 Gs, f = 60 Hz) group and the alternative magnetic field intermittent treatment (B = 20 Gs, f = 60 Hz, t = 12 h) group both obviously have a lower respiration rate, polyphenol oxidase (PPO) activity, and degree of CI in the refrigerated storage condition of T = 6°C and RH = 85%. Compared with the CK group, the color difference in the AMCT group is reduced by 19.1% and the malondialdehyde content is only 81.9%, which shows the best chilling injury inhibition effect. Practical Applications The main purpose of this study was to compare the effects of AMCT and AMIT treatment on the CI of bananas. The results demonstrated that magnetic field technology could inhibit the CI of fruits and vegetables effectively, and AMCT treatment was more helpful to the preservation of bananas. This study will further improve the magnetic field treatment technology and provide a safe physical technology for fruit and vegetable freshness preservation. The parameters studied in this article can provide a reference for the development of commercial equipment.

Section: Resultsmentioning

confidence: 99%

Retracted: Different effects of continuous and intermittent alternative magnetic field on inhibiting chilling injury of bananas

J Food Process Engineering

Han

Liu

et al. 2021

“…The weight loss of cherry tomatoes depended on the transport of water through the stem scar and the consumption of nutrient substance in the respiration (Warning et al, 2016). The diffusion force is caused by the water potential gradient and temperature gradient between cherry tomato's intercellular space and the environment.…”

Section: Heat and Mass Transfermentioning

confidence: 99%

Comparison study of static and alternating magnetic field treatments on the quality preservation effect of cherry tomato at low temperature

Yang

Zhang

J Food Process Engineering

et al. 2020

The objective of this study is to investigate the effects of a static magnetic field (SMF) and alternating magnetic field (AMF) treatment on thermophysical property and preservation quality of cherry tomato. Freshly harvested cherry tomatoes were treated with SMF and AMF at 40 Gs and 80 Gs when hydrocooling pretreatment was performed at 2°C for 30 min. Control tomato fruits were hydrocooled without magnetic field treatment at 2°C for 30 min. The cooling rate, weight loss, color difference, electrical conductivity, malondialdehyde, and catalase were measured. The results showed that the cooling time of SMF treatment was decreased by 16.7% compared with the control treatment. SMF and AMF treatments significantly (p < .05) increased catalase activity and improved the quality of cherry tomatoes during storage. AMF strength at 80 Gs, was the best treatment for reducing weight loss and increasing catalase activity, while the smallest color difference was observed when the SMF at 40 Gs was applied. The results demonstrated that SMF is an alternative method to delay the postharvest ripening process and maintaining the quality of the cherry tomato, which could be due to the higher activity of the antioxidant enzyme catalase. Practical applications The main aim of this study was to compare the effects of SMF and AMF treatment on the preservation quality of cherry tomato. The results demonstrated that magnetic field technology could be applied to fruit and vegetable preservation, and SMF treatment was more helpful to inhibit the ripening of the cherry tomato. This study will broaden the knowledge of food preservation engineers and provide an alternative technology of fruit and vegetable preservation. The parameters used in this study can provide a reference for the development of commercial equipment.

“…Less E. coli internalization distance and area was observed at refrigeration temperatures (4 and 10 °C), but the viability of E. coli was weaker at 4 °C. The internalization is probably due to the fact that vascular bundles, xylem vessels function in transporting nutrients and water, thus providing access to E. coli to the internal tissues 42 , 43 . But the refrigeration temperatures were not suitable for bacterial growth, they could reduce the activity of E. coli .…”

Section: Resultsmentioning

confidence: 99%

Monitoring of transfer and internalization of Escherichia coli from inoculated knives to fresh cut cucumbers (Cucumis sativus L.) using bioluminescence imaging

Sun

Xiao

et al. 2021

Sci Rep

Slicing may cause the risk of cross-contamination in cucumber. In this study, knife inoculated with Escherichia coli (E. coli) was used to cut cucumbers, bioluminescence imaging (BLI) was used to visualize the possible distribution and internalization of E. coli during cutting and storage. Results showed that the initial two slices resulted in greater bacterial transfer. The bacterial transfer exhibited a fluctuating decay trend, E. coli was most distributed at the initial cutting site. The contaminated area on the surface of cucumber slices decreased during the storage period, which can be attributed to the death and internalization of E. coli. The maximum internalization distance of E. coli was about 2–3 mm, and did not further spread after 30 min from inoculation. Hence, our results provide useful information for risk management in both home and industrial environment.