怎样挑选蔬菜和水果
挑选蔬菜和水果时需要注意三点：
一是不买颜色异常的蔬菜和水果。新鲜蔬菜和水果不是颜色越鲜艳越好，如购买萝卜时要检查萝卜是否掉色；发现干豆角的颜色比其他的鲜艳时要慎选。
二是不买形状异常的蔬菜和水果。不新鲜的蔬菜和水果有萎蔫、干枯、损伤、扭曲病变等异常形态；有的蔬菜由于使用了激素物质，会畸形。
三是不买有异常气味的蔬菜和水果。不法商贩为了使有些蔬菜和水果更好看，用化学药剂进行浸泡。这些物质有异味，而且不容易被冲洗掉。
怎样选购肉制品
消费者在购买肉制品时要“五看”：
一看产品认证标志：生产企业是否获得食品生产许可证，有无“QS”标志。
二看生产日期：越新鲜的产品口味越好，产品存放时间越长，氧化现象就越严重。
三看产品表面：要选择表面干爽的产品，表面不干爽的肉制品容易有细菌繁殖，腐败变质。
四看产品外观色泽：颜色过于鲜艳的肉制品有可能添加过量色素，不要购买。
五看产品弹性：弹性好的肉制品内在质量好。
怎样选购大米
一闻：优质的大米会有一种特有的清香，人们通过嗅觉可以辨别出来。
二尝：优质的大米放在嘴里生吃时不会有异味，而且容易被咬碎，舌头能尝到淀粉的味道。
三抓：优质的大米经过手在袋中反复抓后，人们能够清晰地看到袋子周围和手上有白色物质出现，这是“整容”的陈米不具备的。
四冲：优质的大米经温水冲洗不会产生大量杂质，而劣米和一些“整容”的大米冲泡后会在水中沉淀大量杂质，加入的油、蜡经水泡后也会现出原形。
怎样鉴别和保存食用油
1.花生油掺假后透明度下降，把油从瓶中快速倒入杯内，观察泛起的油花，纯花生油的油花泡沫大，周围有很多小泡沫且不易破裂。
2.掺入桐油、蓖麻油、矿物油的食用油，食后轻者中毒，重者死亡。检查时多用化学方法，如检查有无桐油，可取5滴油放于试管中，加浓硫酸5滴，用60度温水，加热15分钟，如出现云雾状或块状可判断有桐油存在。
食用油日常储存，不适合用透明塑料瓶装，应该采用避光深色玻璃瓶，防止接触阳光氧化变质。
尽量用玻璃瓶装盛，且要避开炉灶摆放，因为厨房炉灶旁温度高，油脂长时间受热后，分解出的亚油酸易与空气中的氧发生化学反应，产生醛、酮和其他有毒物质，食用这种油会出现恶心、呕吐、腹泻等症状。
FreeMarker template error:
The following has evaluated to null or missing:
==> zxzx.logo [in template "zixun/mip_baoguang_xiangxi.ftl" at line 232, column 30]
Tip: If the failing expression is known to be legally null/missing, either specify a default value with myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing. (These only cover the last step of the expression; to cover the whole expression, use parenthessis: (myOptionVar.foo)!myDefault, (myOptionVar.foo)??
The failing instruction (FTL stack trace):
----------
==> #if zxzx.logo != "" [in template "zixun/mip_baoguang_xiangxi.ftl" at line 232, column 25]
----------
Java stack trace (for programmers):
----------
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:98)
at freemarker.core.EvalUtil.compare(EvalUtil.java:230)
at freemarker.core.EvalUtil.compare(EvalUtil.java:148)
at freemarker.core.ComparisonExpression.evalToBoolean(ComparisonExpression.java:103)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.MixedContent.accept(MixedContent.java:93)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:193)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:509)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:103)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:86)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.MixedContent.accept(MixedContent.java:93)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.Environment.process(Environment.java:243)
at freemarker.template.Template.process(Template.java:277)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:366)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:283)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:233)
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:167)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.bbaqw.mip.html.filter.CacheFilter.doFilter(CacheFilter.java:86)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.bbaqw.mip.util.AppUrlFilter.sendMsite(AppUrlFilter.java:293)
at com.bbaqw.mip.util.AppUrlFilter.doFilter(AppUrlFilter.java:123)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:748)