优质稻谷保鲜储藏方法研究

将用热风就仓干燥、自然风就仓干燥和烘干机干燥到水分为15%左右的优质籼稻在准低温条件下储藏10个月;将水分为17%的同种优质籼稻在低温条件下储藏13个月。在储藏期间定期测定和稻谷品质有关的13项检测项目。稻谷在储藏期间未发现发热、生霉、生虫等现象,色泽、气味正常,各检测项目测定结果表明,试验结束与试验开始的数值变化不大,一般都在10%以内,因此可以认为稻谷在储藏期间品质一直新鲜。提出保鲜储藏的合理储藏期和保鲜优质籼稻品质判定标准。     

三种干燥方式处理对稻谷品质的影响研究

以旋转通风仓干燥、自然干燥和机械干燥3种方式对新收获稻谷进行降水处理。对干燥后稻谷脂肪酸值、发芽率、爆腰率、出糙率、整精米率及食味值的变化规律进行研究。结果表明:烘干稻谷脂肪酸值为19.9 mg/100 g,低于旋转仓干燥稻谷的25.3 mg/100 g和晾干稻谷的25.1 mg/100 g;高温影响稻谷种子活力,烘干稻谷发芽率为58.0%,远低于旋转仓干燥稻谷的86.5%和晾干稻谷的87.5%;另外,烘干稻谷加工成大米的爆腰率、出糙率、整精米率和食味值分别是5.33%、79.23%、57.9%、83.7,对比旋转仓稻谷的1.33%、80.27%、61.10%、87.0和晾干稻谷的2.33%、76.83%、58.9%、89.3,其加工品质和食味品质更差。利用变异系数法对3种干燥稻谷综合评分,结果表明,旋转通风仓干燥稻谷品质最优,自然干燥次之,机械干燥稻谷品质最差。实验表明,旋转通风仓干燥能很好地保护稻谷品质,适合在中国农村地区推广应用。     

氮气气调启封后粳稻品质变化规律研究

本文以实仓储藏粳稻为原料,从储藏,加工外观,糊化特性和质构特性等角度分析氮气气调启封后粳稻品质变化规律,并与常规储藏稻谷品质进行对比,以期为氮气气调启封后稻谷品质变化过程和规律提供数据支撑。结果表明：在准低温实仓储藏条件中,气调启封后粳稻的脂肪酸值、新鲜度、发芽率、真菌孢子数等指标变化差异不明显,整精米率,垩白率、黄粒米率、糊化特性、硬度等品质指标变化幅度大于对照仓,其中垩白率和黄粒米率变化最为明显,启封储藏前后气调仓比对照仓分别多增加了1.63-10.38%和0.93-2.09%。通过主成分分析图,能清楚区分不同粮库和储藏时间的稻谷,但不能很好区分是否进行了氮气气调。     

优质稻谷准低温储藏与常温储藏品质变化的比较研究

本文研究了优质稻谷在准低温储藏条件下的品质变化,并与常温储藏的品质变化做对比,以期为优质稻谷准低温储藏下的储备周期提供依据。将两种优质稻谷黄华占和两优放入实验模拟仓中储藏,控制环境温度20℃以下,以常温储藏作为对照。每两个月取样对其色泽、气味、脂肪酸值、品尝评分值、黄粒米含量、直链淀粉含量、出糙率、整精米率、过氧化氢酶活动度、发芽率等储藏品质指标、质量指标、加工品质指标、生理品质指标以及糊化特性和质构特性进行测定和分析。结果表明,低温储藏较常温储藏更能延缓优质稻谷品质的劣变,根据GB/T 20569《稻谷储存品质判定规则》,建议准低温储藏的优质稻谷的储备周期不超过18个月。     

粮食就仓干燥技术研究与应用

粮食就仓干燥技术主要是一种集干燥、仓储为一体的技术形式,是将新收获的粮食直接装入配有机械通风系统的储粮仓内,通常使用常温空气进行干燥,在环境湿度较高的情况下,通过加热降低空气湿度,用热空气作为干燥介质,模拟粮食自然晾晒环境风温条件,对仓内粮食进行低温通风干燥,保证粮食安全和品质的一种干燥储藏技术。笔者通过对粮食就仓干燥技术进行介绍,阐述了就仓干燥技术的机理与过程,论述了粮食就仓干燥技术研究与应用的现状,对现阶段就仓干燥技术发展所遇到的难题进行了探讨,并对其发展前景进行了展望。     

低温热泵穿流干燥新鲜稻谷实验研究

利用自主研发的搅拌式-热泵穿流干燥仓,研究了新鲜稻谷的脱水过程.考察了热泵干燥条件对稻谷干燥品质和过程性能的影响.结果表明,稻谷热泵干燥一直处于降速干燥阶段;当热泵干燥温度为35℃时,干燥仓可用7.5h将300kg稻谷从25％的初始含水率降至14％,过程单位能耗为2022kJ/kg water,爆腰增率为1.3％.通过与热风干燥、自然晒干过程比较发现,较之自然晒干,热泵干燥可以大幅度缩短干燥时间,阻止稻谷发霉;较之热风干燥,温和的热泵干燥可以获得较低的爆腰增率,单位能耗低.该结论可以为基于热泵干燥技术的循环式干燥机以及间歇式大型干燥机械的开发提供依据.     

海南省农村小规模储粮技术研究

采用新型PE仓为储具,结合植物源杀虫剂为储粮防护剂,稻谷储藏240 d后,水分变化≤0.4%,与储藏前水分无显著差异。分别在0.5%香茅草、0.5%花椒处理条件下,储粮虫口密度为2头/kg,达到基本无虫水平,虫蚀粒率≤2.8%,霉变粒率≤0.3%,粮食损失率≤0.73%,干物质损失率≤1.11%。粮食品尝评分值变化≤4分,与储藏前评分值无显著差异。因此,采用PE仓与植物源杀虫剂配合使用不仅能减小海南地区因高温、高湿带来的农户储粮质量损失,也能有效的保证粮食在储藏过程中的品质。     

干燥处理对稻谷吸湿产生裂纹敏感性的影响

研究了阴干、日晒、热风干燥三种干燥处理对稻谷早籼9711吸湿产生裂纹的影响,进一步证实了不同干燥处理后的稻谷吸湿产生裂纹的敏感性存在差异,阴干处理的稻谷吸湿产生裂纹的敏感性最低,热风干燥敏感性最高,低温干燥和低温储藏可降低稻谷吸湿产生裂纹的敏感性.     

整仓环流结合压盖储粮技术对东北地区偏高水分稻谷品质的影响

采用常规储藏,整仓环流结合压盖储粮技术对东北地区偏高水分稻谷度夏储藏期间(180 d)的粮温、水分、储藏品质、种用品质和糊化品质进行对比分析。在检测期间,整仓环流结合压盖技术比常规储藏表层粮温低25.8%。整仓环流结合压盖储藏下储粮水分为14.77%,比常规储藏高0.41%。整仓环流结合压盖方式下脂肪酸值为18.66 mgKOH/100g,比常规储藏低4.86 mgKOH/100g。整仓环流结合压盖方式下发芽率为94%。糊化品质分析结果表明整仓环流结合压盖方式储藏的稻谷具有良好的加工稳定性。在东北地区采用整仓环流结合压盖储粮技术储藏偏高水分稻谷能够有效控制粮温,提高粮食的保水率,滞后脂肪酸的上升速率,保证稻谷品质。     

糙米储藏技术研究进展

概述了糙米的常温储藏、低温储藏、气调储藏和保鲜新技术等四种储藏方法,重点从低温储粮原理、实现方法、低温仓设计等三个方面介绍了糙米低温储藏技术的研究进展,分析认为:(1)我国不同水稻产区应当根据其气候特点与后续利用方式,选择适宜的糙米储藏方法;(2)对于高温湿热产区,建议探讨先稻谷储藏再糙米储藏的组合式储藏方法,以期降低储藏能耗,改善糙米品质;(3)进一步通过理论与试验研究,优化低温储藏方法,改善粮仓设计,降低储藏成本,从而突现糙米低温储藏的价值;(4)不断宣传糙米的营养价值.     

Effect of superheated-steam drying compared to conventional parboiling on chalkiness,head rice yield and quality of chalky rice kernels

Four rice cultivars (Ayutthaya 1, Khao Bahn Nah 432, Plai Ngahm Prachin Buri, and Prachin Buri 2) that usually have a major problem with chalkiness were processed by applying superheated-steam drying and conventional parboiling methods. The main objectives were: (1) to determine the possibility of applying superheated-steam drying to solve the chalkiness and low head rice yield problems and (2) to compare the properties of rice produced using superheated-steam drying and the conventional parboiling process. Both the initial moisture content and superheated-steam drying temperature significantly affected head rice yield. The higher moisture helped to increase starch gelatinization leading to a stronger rice structure and subsequently an increased head rice yield. The rice samples dried in the superheated-steam dryer using an initial moisture content of paddy at 32% w.b. for 6 h under a steam pressure of 1.2 bar and at three drying temperatures (120, 140, 160 °C) had higher milling quality than the conventionally parboiled rice samples. The darker color of the superheated-steam-dried samples was their main drawback. Both parboiling and superheated-steam drying could clearly lessen the percentage of chalky rice kernels compared to the raw paddy. The parboiled rice and superheated-steam-dried rice had more nutrients than normal white rice.     

干燥对稻谷籽粒微观结构的影响研究

应用扫描电镜研究了不同干燥方式对稻谷微观结构的影响 ,结果表明 :微裂纹广泛存在于稻谷籽粒中 ,不同干燥方式处理的稻谷籽粒结构存在差异 ,热风干燥处理的稻谷籽粒中的微裂纹比阴干处理的稻谷籽粒中的微裂纹粗大 ,稻谷在干燥过程中产生的微裂纹导致其吸湿产生宏观裂纹 ,稻谷吸湿产生裂纹的敏感性与籽粒中存在的微裂纹的大小存在相关性 ,微裂纹越粗大 ,则稻谷吸湿后越易产生宏观裂纹。     

稻谷热风与真空干燥特性及其加工品质的对比研究

比较稻谷热风与真空干燥特性及对其加工品质的影响,为有效改善稻谷加工品质提供依据。通过对初始水分为26.5%的稻谷进行热风和真空干燥试验,研究热风干燥和真空干燥对稻谷的干燥特性和其加工品质的影响。结果表明:干燥温度越高,稻谷的平均降水速率越大,且真空干燥平均最大降水速率大于热风干燥平均最大降水速率;热风干燥在干燥开始后的5～10min降水速率出现最大值,真空干燥在干燥开始后的5～15min降水速率出现最大值。随着干燥温度的升高,稻谷的爆腰率上升,出糙率和整精米率下降;相同的干燥温度下,真空干燥稻谷的加工品质优于热风干燥稻谷的,其中爆腰率最为明显。对于高水分稻谷采用真空干燥可以提高稻谷的加工品质。     

流化床和薄层热风干燥对稻谷品质的影响

研究流化床和薄层热风干燥在干燥温度50、60、70 ℃条件下对高水分稻谷水分变化的影响,分析稻谷加 工品质（爆腰率）和稻米质构品质（硬度、黏着性、咀嚼性）的变化规律。结果表明：初始含水率相同的稻谷, 在同一干燥温度条件下流化床干燥速率大于薄层热风干燥,但是加工品质略差,对发芽率没有影响。干燥温度为 50 ℃时,流化床和薄层热风干燥稻米的品质较好。稻谷干燥温度和整精米率之间呈显著的负相关。流化床干燥后 稻米的硬度、黏着性、胶性与爆腰率呈显著性相关,薄层热风干燥后稻米黏着性、胶性与爆腰率呈显著性相关,其 他质构指标相关性均不显著。     

Penetration of juice into rice through vacuum drying

Vacuum drying was employed to penetrate rice with juice. Red beetroot juice, good source of color and functional compounds, was used. After mixing with beetroot juice and vacuum drying, cracks were formed in the rice kernel surface and the rice kernels were a red-violet color. The degree of visual kernel surface cracking, the fracturability of whole rice kernels, and the DPPH scavenging activity were increased with increasing amounts of added juice. The visual kernel surface cracking was found to be beneficial for deep penetration and juice accumulation within three varieties of rice kernels (Sanpatong 1, Kaow Dok Mali 105, and Chainat 1) and two storage time periods (one month and one year). The final moisture content of the rice kernels after vacuum drying was sufficiently low for good storage quality. No heat treatment is required. The findings imply that other functional liquids/solutions would be also vacuum-impregnated in rice grains. Functional properties of rice could be effectively improved with a vacuum drying technique.     

基于多品质指标的响应面试验优化稻谷流化床干燥工艺

为优化稻谷流化床干燥工艺,采用三因素三水平Box-Behnken响应面分析法,研究干燥温度、降水幅度、缓苏时间对稻谷流化床干燥降水速率和干燥稻谷爆腰增率、垩白粒率、脂肪酸值、硬度、黏着性等品质指标的影响。结果表明：随着干燥温度和降水幅度水平的增加,稻谷降水速率、爆腰增率、垩白粒率和米饭硬度增加,脂肪酸值和米饭黏着性降低;随着缓苏时间延长,稻谷降水速率、爆腰增率、脂肪酸值和米饭硬度降低,米饭黏着性增加。而在较低的干燥温度条件下,缓苏时间延长,稻谷的爆腰增率和垩白粒率降低并不明显。Box-Behnken响应面分析法优化的流化床最优干燥参数为降水幅度2.50%（干基）、干燥温度45 ℃、缓苏时间3 h,此时隶属度综合分达最大值0.75。验证实验结果与拟合值无显著性差异（P＜0.05）,优化结果可靠有效。     

Effect of pre-steaming on production of partially-parboiled rice using hot-air fluidization technique

Fluidization technique was widely used to dry agriculture products because of its effectiveness in drying. To produce partial-parboiled rice using hot-air fluidization technique has been received increasing attention due to simplicity of operation. Thus, the purpose of this work was to investigate the effects of pre-steaming time and drying temperatures on qualities of partial-parboiled rice. The results revealed that head rice yield, pasting temperature and degree of gelatinization increased with an increase in pre-steaming time whereas white belly decreased. The percentage of water uptake of pre-steamed rice decreased with an increase in drying temperature while the percentage of solid loss and stickiness were not affected. The hardness of pre-steamed rice was higher than that of reference rice and it increased with an increase in drying temperature. To obtain the suitable conditions for producing partially-parboiled rice using hot-air fluidization technique, paddy was soaked at temperature of 80 °C for 5 h and then it was blown with saturated steam temperature of 102 °C for 70 s (pre-steaming). After that it was dried using fluidization technique at hot-air temperature of 140 °C for 2 min and then it was tempered for 30 min; furthermore, it was ventilated at ambient air temperature until the final moisture content was approximately 14–16% d.b.     

Development of Mobile Dryer for Freshly Harvested Paddy

Presently, due to an increase in usage of large scale mechanical threshers and combine harvesters, moisture content of freshly harvested paddy is being high as much as 18-24%. The mechanical threshers or combine harvesters with elevated capacity enable for both harvesting and threshing at once. Thus the paddy harvested all over persists with high moisture content that affects adversely in unit operations of paddy processing such as cleaning, storing, and milling. The research was conducted to overcome this problem by developing a mobile paddy dryer that can be used at field level for freshly harvested paddy. A mobile dryer, one ton capacity, was developed and tested for drying freshly harvested paddy. The performance of the mobile dryer was evaluated in terms of overall thermal efficiency, heat utilization factor, coefficient of performance, total heat efficiency and head rice yields. The overall thermal efficiency of this dryer was 46.83%. The average heating efficiencies namely heat utilization factor and total heat efficiency were 0.82 and 0.72 respectively. The coefficient of performance of the developed dryer was 0.18. The head rice yields of freshly harvested paddy after drying at 60 °C air temperature was of 73.78%. The overall drying performance of the dryer was found to be good.     

南方夏季稻谷热泵干燥特性研究

利用热泵除湿,控制空气绝对湿度为21.5~23.8g/kg(干空气),研究了温度、风量和湿度对稻谷干燥速率、爆腰和发芽率的影响。结果表明:南方夏季高湿稻谷在14%~26%的干燥过程中含水率对干燥速率影响很小,于燥曲线近似直线,线性拟合得到了温度-风量-平均干燥速率参数选择区域图,具有实践生产指导意义;在优化区域选择参数时,当温度为50℃,应控制风量小于20m~3/kg·h,干燥所得稻谷的品质良好     

MOISTURE DESORPTION OF PADDY BY TWO DIFFERENT POROUS MEDIA: MATHEMATICAL MODELS AND EXPERIMENTAL DATA

The aim of this work was to study the moisture reduction of paddy by two different adsorbents, tapioca flour and rice husk. The effects of the mixed ratio of adsorbent to paddy, the initial moisture content of adsorbent and the number of times of adsorbent replacement on the moisture desorption of paddy, moisture adsorption of adsorbent and milling qualities were investigated. The mathematical models were developed for predicting the moisture desorption of paddy and moisture adsorption of adsorbent. Experimental one-pass sorption results revealed that the higher mixed ratio and lower initial moisture content of adsorbent provided the higher moisture reduction rate of paddy and gave the higher water adsorption of adsorbent. It was also found that mixed ratio, initial moisture content and the number of times of adsorbent replacement had no obvious effect on percentage of head rice yield and whiteness of milled rice. Page's model was fitted properly with the experimental desorption and adsorption data.

PRACTICAL APPLICATIONS

Adsorption is a useful process in order to maintain some qualities of heat-sensitive product because it operates at low temperature. Adsorption is a time-consuming process to remove moisture of adsorbate until its moisture is down to safe storage. This is because drying rate is controlled by diffusion of a product. Slow diffusion rate can prevent the quality loss of product during the drying process. The investigation involving moisture desorption of agricultural products by different kinds of adsorbent will provide more understanding on the mechanism of sorption process.