一、看标签。买冷冻食品最好去正规超市、卖场，选购有资质企业的品牌产品;要注意查看产品的生产日期、保质期和“SC”标志;产品包装要密封完整;产品表面坚硬，未出现软化现象;肉禽产品要无大量血水冰块残留;一次购买量不要太大，以一周食用量为宜。购买冷冻肉时，一定要特别留意标签上的生产日期。
二、眼观。眼观就是看超市里的冷柜够不够“冷”，冷柜温度是否够低，一般需要保持在-15℃以下，开袋食用前再看冷冻食品的外表够不够“纯”，真正的冷冻食品是在速冻机上以最快的速度和时间通过0℃至5℃的水晶带。因此，产品颜色应与速冻前新鲜产品是一致的。如果产品的色泽发灰、发暗、发黄，表示产品有储存、运输等过程温度未达到要求，产品已经变质，不宜食用。
三、手捏。手捏就是拿起包装，用手轻捏产品，摸上去如果软绵绵的、颜色发黄，就说明冷冻时间已经过长，有可能是变质产品，这种肉不能买。
四、鼻嗅。腐败变质的产品会有酸败味或者肉汁粘腻、浑浊，所以用鼻子嗅一嗅也是必要的，如有酸败味，产品已经变质，不宜食用。
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)