本文選題：花椒　切入點(diǎn)：真空干燥　出處：《西南大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：新鮮花椒采收后含水率高達(dá)200%.d.b,在貯藏過程中極易受外界條件的影響,發(fā)生質(zhì)變,造成巨大損失。干燥是花椒收獲后重要的處理環(huán)節(jié),對(duì)花椒的運(yùn)輸、貯藏等起到重要的作用,但若干燥處理不當(dāng),則會(huì)造成花椒品質(zhì)嚴(yán)重受損,營養(yǎng)物質(zhì)流失嚴(yán)重,降低其經(jīng)濟(jì)效益。傳統(tǒng)的干燥方式存在干燥效率低、干燥品質(zhì)差等缺點(diǎn),而真空干燥是一種新型熱門的干燥技術(shù),具有節(jié)能、環(huán)保、干燥品質(zhì)好等優(yōu)點(diǎn)。本文將采用真空干燥對(duì)花椒進(jìn)行以下幾個(gè)方面的研究:(1)研究了花椒的真空干燥特性。選取溫度(50、60、70℃)、真空度(-0.02、-0.04、-0.06Mpa)和載重量(30、40、50g)對(duì)花椒進(jìn)行三水平三因素的全面試驗(yàn)研究。對(duì)不同溫度、真空度和載重量條件下花椒的真空干燥特性進(jìn)行研究;選取決定系數(shù)R2、殘差平方和SSE和卡方χ2作為模型評(píng)價(jià)指標(biāo)對(duì)水分比-時(shí)間干燥曲線進(jìn)行了7種經(jīng)典數(shù)學(xué)模型的擬合,結(jié)果表明三次多項(xiàng)式模型具有較大的決定系數(shù)和較小的誤差值,是最適合描述花椒真空干燥的數(shù)學(xué)模型。(2)建立花椒真空干燥BP神經(jīng)網(wǎng)絡(luò)模型。以時(shí)間、真空度、溫度和載重量為輸入神經(jīng)元,水分比為輸出神經(jīng)元,利用Matlab神經(jīng)網(wǎng)絡(luò)工具箱對(duì)全面試驗(yàn)的25組896個(gè)試驗(yàn)數(shù)據(jù)作為訓(xùn)練樣本進(jìn)行訓(xùn)練,再把另外2組試驗(yàn)作為檢驗(yàn)樣本進(jìn)行擬合檢驗(yàn),結(jié)果表明BP神經(jīng)網(wǎng)絡(luò)模型擬合性很高,兩個(gè)檢驗(yàn)樣本的平均相對(duì)誤差分別為8.698%和6.593%,通過BP神經(jīng)網(wǎng)絡(luò)能直接準(zhǔn)確的預(yù)測(cè)花椒真空干燥過程中的水分比變化。(3)基于Weibull函數(shù)的花椒真空干燥模型建立及過程解析。利用Weibull函數(shù)及其尺度參數(shù)α和形狀參數(shù)β在干燥理論中的意義對(duì)花椒真空干燥進(jìn)行解析及模型建立。結(jié)果表明,Weibull函數(shù)模型對(duì)花椒真空干燥過程擬合度高;溫度是影響花椒真空干燥的主要因素,隨著溫度的升高,Weibull模型的尺度參數(shù)α值減小,有效水分?jǐn)U散系數(shù)增大,說明干燥速率增大,所用的干燥時(shí)間縮短;Weibull函數(shù)的形狀參數(shù)β大于1表明花椒真空干燥過程中有明顯的升速階段。(4)本論文以開口率和色差值為花椒真空干燥評(píng)價(jià)指標(biāo)初探花椒真空干燥品質(zhì)。試驗(yàn)結(jié)果表明干燥溫度越高,花椒色差值越大;干燥溫度和真空度越高,開口率越高。為了獲得高品質(zhì)的花椒制品,在進(jìn)行花椒干燥時(shí)盡量采用低溫干燥。(5)花椒真空干燥工藝優(yōu)化。選取三個(gè)因子和三個(gè)指標(biāo)進(jìn)行了三元二次旋轉(zhuǎn)回歸組合試驗(yàn)設(shè)計(jì),借助Design-Expert 8.0軟件工具,通過響應(yīng)面法進(jìn)行單指標(biāo)參數(shù)優(yōu)化,再通過加權(quán)評(píng)分法進(jìn)行多指標(biāo)綜合優(yōu)化最終確定花椒真空干燥的最佳工藝參數(shù)為:溫度62.18℃,真空度-0.054Mpa,裝載量37.23g。在此試驗(yàn)條件下,各個(gè)指標(biāo)的相對(duì)誤差均小于10%,可靠度高。
[Abstract]:The moisture content of fresh Zanthoxylum bungeanum after harvest is as high as 200.d.b. it is easy to be affected by external conditions during storage, resulting in great loss. Drying is an important process after harvest and plays an important role in transportation and storage of Zanthoxylum bungeanum. However, if the drying process is not proper, the quality of Zanthoxylum bungeanum will be seriously damaged, the loss of nutrients will be serious, and its economic benefit will be reduced. The traditional drying method has the disadvantages of low drying efficiency and poor drying quality. Vacuum drying is a new and popular drying technology with energy saving and environmental protection. The vacuum drying characteristics of Zanthoxylum bungeanum were studied by vacuum drying in the following aspects: 1) the vacuum drying characteristics of Zanthoxylum bungeanum were studied. A comprehensive experimental study of three factors. For different temperatures, The vacuum drying characteristics of Zanthoxylum bungeanum under vacuum and deadweight conditions were studied, and seven classical mathematical models were fitted with the determination coefficient R2, residual square and SSE and chi-square 蠂 2. The results show that the cubic polynomial model is the most suitable mathematical model to describe the vacuum drying of Chinese prickly ash, and the cubic polynomial model has a large determining coefficient and a small error value, and the BP neural network model for vacuum drying of Chinese prickly ash is established. The time, vacuum degree and vacuum degree are used to establish the BP neural network model for vacuum drying of prickly ash. The temperature and deadweight were input neurons and the water ratio was output neurons. The Matlab neural network toolbox was used to train 896 experimental data of 25 groups. Then the other two groups of experiments were used as test samples to carry out fitting test. The results show that the BP neural network model has high fitting ability. The average relative error of the two test samples is 8.698% and 6.593respectively. BP neural network can directly and accurately predict the change of water ratio in the vacuum drying process of prickly ash.) based on Weibull function, the vacuum drying model of Chinese prickly ash and its process solution can be established. Using the meaning of Weibull function and its scale parameter 偽 and shape parameter 尾 in drying theory, the vacuum drying of prickly ash was analyzed and the model was established. The results showed that the Weibull function model had high fit for the vacuum drying process of prickly ash. Temperature is the main factor affecting vacuum drying of Zanthoxylum bungeanum. With the increase of temperature, the scale parameter 偽 value of Weibull model decreases and the effective moisture diffusion coefficient increases, which indicates that the drying rate increases. The shape parameter 尾 of Weibull function is greater than 1, which indicates that there is a significant increasing speed stage in vacuum drying of Chinese prickly ash.) in this paper, the opening rate and color difference value are used as the evaluation index of vacuum drying of Chinese prickly ash. Drying quality. The test results show that the higher the drying temperature, The greater the color difference value, the higher the drying temperature and vacuum, the higher the opening rate. The vacuum drying process of Zanthoxylum bungeanum was optimized by using low temperature drying. Three factors and three indexes were selected to design the three dimensional quadratic rotation regression test, and the software Design-Expert 8.0 was used to design the optimal vacuum drying process of Zanthoxylum bungeanum L. The single parameter is optimized by response surface method, and the optimum technological parameters of vacuum drying of Chinese prickly ash are determined by weighted scoring method. The optimum technological parameters are: temperature 62.18 鈩，

本文編號(hào)：1648476