The changes in respiration rates, malondialdehyde (MDA) content and antioxidant enzyme activities of fresh-cut green peppers treated with ozone (6.42 mg/cm 3 , 15 min), modified atmosphere packaging (MAP; 3% O 2 , 4% CO 2 and 93% N 2 ) and ozone 1 MAP during storage at 5C for 21 days were investigated in a laboratory environment. The three treatments all reduced respiration rates and MDA content compared to the control group. The enzyme activities in fresh-cut green peppers including peroxidase (POD), superoxidase dismutase (SOD) and L-phenylalanin ammonia-lyase (PAL) were induced by ozone and MAP treatments while polyphenol oxidase (PPO) activities were inhibited. And a much better effect was observed when the ozone and MAP treatment were combined which indicated ozone and MAP had a synergistic effect on inhibiting the respiration rates and the predication of MAD by enhancing the effectiveness of the antioxidant defense system through enhancing the activity of POD, SOD, PAL and inhibiting the activity of PPO. PRACTICAL APPLICATIONSBecause of the nutritional qualities and convenience, fresh-cut fruits and vegetables have gained popularity in recent years. However, fresh-cut fruits and vegetables shelf ife are limited due to the natural inherent barriers of fruits and vegetables are damaged during processing. The antioxidant defense system which consists of a series of antioxidase such as superoxidase dismutase, peroxidase, catalase, is an important enzyme system which can inhibit oxidation reactions in tissues. It is beneficial for extending shelf life of fresh-cut fruits and vegetables. This study has given an experimental evidence that ozone and modified atmosphere packaging (MAP) both can enhance the effectiveness of the antioxidant defense system. And the combination of ozone and MAP treatment can enhance the induction. Thus, ozone and MAP treatment have the advantages of prolonging shelf life of fresh-cut fruits and vegetables.

No abstract

No abstract

The rolling bearings often suffer from compound fault in practice. Compared with single fault, compound fault contains multiple fault features that are coupled together and make it difficult to detect and extract all fault features by traditional methods such as Hilbert envelope demodulation, wavelet transform and empirical node decomposition (EMD). In order to realize the compound fault diagnosis of rolling bearings and improve the diagnostic accuracy, we developed negentropy spectrum decomposition (NSD), which is based on fast empirical wavelet transform (FEWT) and spectral negentropy, with cyclic extraction as the extraction method. The infogram is constructed by FEWT combined with spectral negentropy to select the best band center and bandwidth for band-pass filtering. The filtered signal is used as a new measured signal, and the fast empirical wavelet transform combined with spectral negentropy is used to filter the new measured signal again. This operation is repeated to achieve cyclic extraction, until the signal no longer contains obvious fault features. After obtaining the envelope of all extracted components, compound fault diagnosis of rolling bearings can be realized. The analysis of the simulation signal and the experimental signal shows that the method can realize the compound fault diagnosis of rolling bearings, which verifies the feasibility and effectiveness of the method. The method proposed in this paper can detect and extract all the fault features of compound fault completely, and it is more reliable for the diagnosis of compound fault. Therefore, the method has practical significance in rolling bearing compound fault diagnosis.

For prediction of the shelf life of the mushroom Agaricus bisporus, the growth curve of the main spoilage microorganisms was studied under isothermal conditions at 2 to 22°C with a modified Gompertz model. The effect of temperature on the growth parameters for the main spoilage microorganisms was quantified and modeled using the square root model. Pseudomonas spp. were the main microorganisms causing A. bisporus decay, and the modified Gompertz model was useful for modelling the growth curve of Pseudomonas spp. All the bias factors values of the model were close to 1. By combining the modified Gompertz model with the square root model, a prediction model to estimate the shelf life of A. bisporus as a function of storage temperature was developed. The model was validated for A. bisporus stored at 6, 12, and 18°C, and adequate agreement was found between the experimental and predicted data.