Risk assessment and ranking of pesticide residues in Chinese pears

The presence of pesticide residues in pears is a serious health concern. This study presents the results from a 2-year investigation （2013-2014） that used gas chromatography, GS/MS and UPLC/MS-MS to measure the levels of 104 pesti- cides in 310 pear samples. In 93.2% of the samples, 43 pesticides were detected, of which the maximum residue levels （MRLs） were exceeded in 2.6% of the samples. Multiple residues （two to eight compounds） were present in 69.7% of the samples; one sample contained nine pesticides and one sample contained 10. Only 6.8% of the samples did not contain residues. To assess the health risks, the pesticide residue data have been combined with daily pear consumption data for children and adult populations. A deterministic model was used to assess the chronic and acute exposures based on the Joint Meeting on Pesticide Residues （JMPR） method. A potential acute risk was demonstrated for children in the case of bifenthrin, which was found to be present at 105.36% of the acute reference dose （ARfD） value. The long- term exposure of the Chinese consumer to pesticide residues through the consumption of raw pears was far below the acceptable daily intake （ADI） criterion. Additionally, the matrix ranking scheme was used to classify risk subgroups of pesticides and pear samples. In general, 95.5% of samples were deemed to be safe and nine pesticides were classified as being of a relatively high risk. The findings indicated that the occurrence of pesticide residues in pears should not be considered a serious public health problem. Nevertheless, a more detailed study is required for vulnerable consumer groups, especially children. Continuous monitoring of pesticides in pears and tighter regulation of pesticide residue standards are recommended.

Evaluation indices of sour flavor for apple fruit and grading standards

In order to establish grading standards of evaluation indices for sour flavor of apples, 10 indices of samples from 106 apple cultivars were tested, including： malic acid（Mal）, oxalic acid（Oxa）, citric acid（Cit）, lactic acid（Lac）, succinic acid（Suc）, fumaric acid（Fum）, total organic acids（To A, the sum of the six organic acids tested）, titratable acid（TiA）, acidity value（AcV）, and pH value. For most of the cultivars studied（85.8%）, the order of the organic acid contents in apples was Mal〉Oxa〉Cit〉Lac〉Suc〉Fum. Mal was the dominant organic acid, on average, accounting for 94.5% of To A. Among the 10 indices, the dispersion of pH value was the smallest with a coefficient of variation of only 8.2%, while the coefficients of variation of the other nine indices were larger, ranging between 31 and 66%. There were significant linear relationships between Mal and two indices（ToA and AcV） as well as between ToA and AcV. There were significant logarithmic relationships between pH value and four indices： Mal, TiA, ToA, and AcV. All the equations had very high fitting accuracy and can be used to accurately predict related indices. According to this study, Mal, ToA, and AcV of apple were normally distributed, TiA was close to normally distributed, whereas pH value had a skewed distribution. Using the fitted normal distribution curves, the grading standards of Mal, TiA, ToA, and AcV were established. The grading node values of pH value were obtained using the logarithmic relationship between pH value and Mal. The grading standards of these five indices can be used to evaluate the sour flavor of apple. This study provides a scientific basis for evaluating apple flavor and selecting apple cultivars.