冰糖橙果实品质无损伤在线检测分级技术的建立与应用

【目的】冰糖橙果实外观分级与内部品质不一致极大地影响了其市场声誉,建立冰糖橙果实品质分级标准和果实快速规模化无损伤品质检测分级技术,并进行在线应用,为快速分选不同糖酸度冰糖橙产品提供技术支持。【方法】在利用常规果实品质分析方法对主产区的冰糖橙果实进行多年品质分析的基础上,找出果实外观和内在品质的相关性,确定不同果型横径与糖酸度含量的关系,形成冰糖橙果实分级标准。在此基础上,采集710—960 nm波段近红外透射光谱建立果实无损伤检测模型,利用常规品质分析数据对原始光谱反复进行校正并验证,确定无损伤检测的准确性,并在分级线上进行应用;调查统计应用无损伤检测生产线分级后各级冰糖橙的产量、销售单价和销售额。【结果】(1)根据果实横径大小进行初选分级,68—74 mm为大果型,62—67 mm为中果型,56—61 mm为小果型,再按果实的糖度(可溶性固形物Brix度)和酸度不同将冰糖橙划分为4个等级:糖度≥14、酸度≤0.4%为特级果;12≤糖度14、酸度≤0.4%为一等果;糖度≥14、0.6%≥酸度0.4%为二等果;糖度12、酸度≤0.4%为合格果。通过反复矫正,建立了冰糖橙果实品质分级标准。(2)通过多次进行单果糖度和酸度的分析矫正,建立了冰糖橙果实糖度和酸度的检验线。第1次建立的冰糖橙糖度检量线检测范围为10.1—14.9 Brix,再利用常规品质分析验证无损伤检测结果,合格率仅为26%。第2次建立的糖度检量线延长高糖检测范围,为10.1—16.2 Brix,经验证后合格率达90%。第3次建立的糖度检量线扩大低糖检测范围,为9.8—16.2 Brix,经验证后合格率为90%。第1次建立的冰糖橙酸度检量线检测范围为0.1%—1.26%,再利用常规品质分析验证无损伤检测结果,合格率仅为64%。第2次建立的酸度检量线延长高酸检测范围,为0.1%—1.37%,经验证后合格率达94%。第3次建立的酸度检量线继续扩大高酸检测范围,为0.1%—1.53%,经验证后合格率为92%。(3)新建立无损伤糖酸度校正和验证模型,糖度有效检测范围为8.7—15.1 Brix,酸度有效检测范围为0.14%—2.0%,经验证后糖度合格率达到98%,酸度合格率为98%。应用该分级技术,分选速度达到10个冰糖橙/秒,品质分级后最高单价48元/kg,年产量4 500 t,实现产值9 122万元。【结论】研究结果预测糖酸度准确,测量范围全面涵盖冰糖橙商品果的糖酸度,能大批量、快速、高质量和无损伤在线鉴别冰糖橙果实内在品质,结合外观品质分级标准,分选出内外品质均一的产品。

Establishment of Non-Destructive System for Fruit Quality Grading of ‘Bingtang’ Sweet Orange and Its Application on Packing Line

【Objective】 The inconsistency between external appearance and the internal quality of ‘Bingtang’ sweet orange (Citrus sinensis Osbeck) fruit has significantly reduced its marketing value. The present research intended to establish the classification standard for fruit quality and the non-destructive technologies for quality analysis and quality rating of ‘Bingtang’ orange, and then to quickly sort out the online products with different total soluble solids (TSS) and acidity. 【Method】 Fruit TSS and acid content were analyzed by sampling from the main production areas with the conventional destructive methods for a long period. The correlation among the external and internal key fruit quality parameters was calculated, and then the relationship between fruit diameter vs. TSS and acid content was determined. A standard for fruit quality classification of ‘Bingtang’ sweet orange was established. Based on the standard, the NIR transmission spectrum at 710-960 nm was utilized for fruit quality analyses, and repeated correction and verification were performed in comparison with the conventional quality analysis data to evaluate the accuracy in non-destructive fruit quality analysis and sorting. This non-destructive system was run on packing line, and the rating products were investigated in the market including the quantity, price and sold volume of different classes of ‘Bingtang’ sweet oranges. 【Result】 (1) Classification standard of ‘Bingtang’ sweet orange was established. Fruit size classification was set up based on fruit diameters: large 68-74 mm, medium 62-67 mm, and small 56-61 mm. And fruits were further classified into 4 classes based on the TSS and acid content, i.e. Super class: Birx≥14 and acidity≤0.4%, Class I: 12≤Birx＜14 and acidity≤0.4%, Class II: Birx ≥14 and 0.6%≥acidity＞0.4%, and Marketable class: Birx＜12 and acidity≤0.4%. (2) Following repeated analyses of single fruits, non-destructive analytical standards for TSS and acidity were formulated. In the 1st TSS testing experimentation, the testing range was set up between 10.1-14.9 Brix and resulted in only 26% of conformity between the non-destructive and the conventional quality analyses; when the TSS testing range extended to 10.1-16.2 Brix in the 2nd experimentation, 90% of conformity was obtained; when the TSS lowered to 9.8 Brix (testing range of 9.8-16.2 Brix) in the 3rd TSS test, the conformity remained as high as 90%. For the acidity analysis, the testing range was set up between 0.1%-1.26% at first, only 64% of the conformity was obtained; when the testing range expanded to 0.1%-1.37%, up to 94% of conformity was realized; if the testing range of acidity increased further to 1.53%, the result was 92% of conformity indicating no improvement was gained. (3) The application of the technique on packing line resulted in a sorting speeds up to 10 oranges per second, and the sorted fruits had a highest price of 48 yuan per kg. On the packing ling, annual sorting output reached 4 500 tons, valuing 91.22 million yuan.【Conclusion】The results indicated that the established non-destructive system was accurate in TSS and acidity analysis and the analytical standards covered the full range of TSS and acidity contents of all the commercial fruits of ‘Bingtang’ sweet orange. The classification with the fast, high-quality and non-destructive online determination of the internal quality of ‘Bingtang’ sweet orange on a large scale combined with the grading standard of fruit size would ensure an unified internal and external quality of the products.