Quality-based grading system and integrated evaluation for Torreya grandis ‘Merrilli'

Abstract:【Objective】The evaluation on nutritional quality is a significant procedure for Torreya grandis ‘Merrilli'breeding and comprehensive utilization. In order to provide technical support for online non-destructive testing in terms to the quality of Torreya grandis ‘Merrilli', the comprehensive evaluation and classification system were established for T. grandis‘Merrilli'quality.【Methods】Thirty nine samples of T. grandis‘Merrilli'from Kuiji Mountain (Zhuji, Shaoxing and Shengzhou) were collected in September, 2016. Twenty two quality indexes (appearance and nutrition) including length, wide, shell thickness, seed weight, kernel weight, shape index with seed, kernel rate, fats, proteins, acid value, peroxide value, palmitic acid, stearic acid, oleic acid, linoleic acid, eicosadienoic acid, eicosatrienoic acid, calcium, potassium, iron, zinc and selenium contents were measured with three replications.The quantitative index of 30 nuts per sample was determined by the conventional method. The method of continuous extraction was used for determination of fat content. The content of protein was assayed by Kjeldahl determination. The fatty acid composition was determined by Agilent 6890 N/5975 MSD.The relative percentages of the oil constituents were quantified by calculating the relative contents based on the peak areas normalization method. The contents of 5 trace elements were determined by ICP-AES. The peroxide value and acid value of seed oil were determined according to GB/T 5009.37—2003. The role of factor analysis using SPSS 19.0 software was performed to filter primary indicators from 22 quality indicators of T. grandis‘Merrilli'. The probability distribution and analytical hierarchy process (AHP) were used to determine indicators' weights in T. grandis‘Merrilli' quality evaluation and grading. The K-means clustering and discriminant analysis were used to set up a discriminant model of T. grandis‘Merrilli'quality.【Results】There were differences and rich diversities in length, wide, shell thickness, seed weight, fat and protein contents, and so on. Twenty two quality indexes among the39 samples showed a variable coefficient rate ranging from 3.14%-111.75%. The peroxide value had the largest variation coefficient of 111.75%. However, kernel rate had the smallest coefficient variation of3.14%. The coefficient variation of shape index with seed was also small. The average content of oil was 58.02% with small variation. There was a certain correlation among T. grandis‘Merrilli'quality evaluation factors. The length showed very positively significant correlation to wide, seed weight and kernel weight (p < 0.01) , respectively. There was a significant positive correlation between length and protein content (p < 0.05) . Eight principal factors were extracted from the 22 nutritional factors, which were contributed to 19.203%, 14.357%, 10.798%, 8.935%, 8.311%, 7.26%, 5.356% and 6.146%, respectively, with a cumulative percentage of 78.886%. While the length, wide, seed weight, kernel weight, protein and acid value could decide the first principal factor, the eicosatrienoic acid, oleic acid and stearic acid could determine the second principal factor; the third principal factor was decided by palmitic acid, eicosadienoic acid and calcium contents, and the selenium, zinc and iron contents decided the fourth principal factor. Seed shape index depended on the fifth principal factor. The linoleic acid content decided the sixth principal factor. The kernel rate decided the seventh principal factor. The protein content decided the eighth principal factor. As for the quality evaluation factors in T. grandis‘Merrilli', the most important value was seed weight (absolute maximum rating) . The second was kernel weight and shape index with seed. Nine typical indices including length, wide, seed weight, kernel weight, seed shape index, oil, kernel rate, protein and acid value were screened from 22 T. grandis‘Merrilli'quality indices by correlation analysis and factor analysis. An analytical hierarchy model was proposed based on the effect of nine indices on T. grandis‘Merrilli'quality, with weight coefficients of these factors being 29.14%, 21.44%、10.95%, 14.99%, 7.84%, 5.79%, 4.29%, 3.20% and 2.36%, respectively. In the experiment, a standard of classification and evaluation was built, and three functions were applied to determine the quality of T. grandis‘Merrilli'. And the accuracy of the functions could reach up to 100% (modeling samples) and 88.88% (test samples) , respectively.【Conclusion】The quality of T. grandis‘Merrilli 'could be evaluated by length, wide, seed weight, kernel weight, seed shape index, oil, kernel rate, protein and acid value. The significance of the study is to provide a scientific basis for establishing a standard of comprehensive assessment and grading system for evaluating T. grandis‘Merrilli' quality.