UHT Processed, Aseptically Packaged Milk, and Its Consumer Benefits

Updated on March 15, 2018

UHT Direct Processing System

Source

What is Ultra High Temperature Processing?

UHT (ultra high temperature) processing is available in many forms. I will focus this article on the direct heating method of steam infusion and a comparison to the conventional HTST pasteurizer. The goal of any milk pasteurization process is to kill pathogenic bacteria while preserving the integrity of the product for the satisfaction of the consumer. While many opinions of milk treatment are widely available, I'll express mine for the benefit of the UHT process with aseptic filling.

In a UHT steam infusion process, milk is produced by exposing the product to high temperatures (>280ºF) in a mixture of steam and milk under pressure for about 2 seconds while maintaining sterile conditions in the processing system. This differs from the conventional HTST pasteurizer requirements of holding milk >161ºF for 15 seconds as shown in the graphic.

Source

HTST: Microbial Contamination and Expiration Dates

A conventional HTST pasteurizer will kill the majority of the bacteria. However, post-production testing across the shelf life of the product will show that microbial contamination will flourish, and this may surprise you. This is usually due to bacteria surviving the pasteurization and post-process contamination from environmental pathogens. Post-processing contamination cannot be avoided unless specialized aseptic filling equipment is used. Government regulations allow up to 20,000 colony forming units per mL of milk. Microbial growth is almost always present in the milk packages produced from a conventional pasteurizer. This is the reason that a conventional pasteurizer will produce milk that will be good for only 14-21 days under refrigeration. The microbial load just gets too high after this time, and sensory degradation accelerates and you soon have spoiled soured milk.

Samples of UHT Packaging Formats

Source

UHT: Microbial Contamination and Expiration Dates

The high-temperature treatment >280-290ºF will kill virtually all bacteria, yeasts and molds that would spoil the milk. This ultra-pasteurization process is the processing step required before filling into packages. The milk is usually filled into two different formats after processing, detailed below:

  • Extended shelf life (ESL) milk products (usually found in 1 quart to 1/2 gallon sizes) are packaged in an environment that poses a minor risk to post-processing contamination. Typical expiration dates of 60-90 days are given to these products, and the milk must be kept refrigerated.
  • When the UHT process is coupled with aseptic filling equipment, there is little risk for post-processing environmental contamination, and the expiration date on these products can be 6-12 months at room temperature in your pantry or on the store shelves. While government regulations still allow up to 20,000 colony forming units per mL of milk - you won't find any microbial growth, even at the expiration date. One reason they don't extend the life of these products is that the sensory characteristics slowly degrade over time, not because of product spoilage but due to bacteria.

Sensory Characteristics HTST vs UHT

One sensory complaint of UHT processed milk is a "cooked flavor." While it can be classified as an off-flavor as compared to HTST or raw milk, I personally feel that the milk has a better flavor profile and is more appealing to the senses. It is the high temperature of the process that imparts this cooked flavor to the milk.

Packaging pasteurized HTST milk into semi-transparent milk jugs allows for the fluorescent lighting to impart an oxidized flavor into the milk, which is not an appealing flavor addition. This problem will not be encountered in aseptically packed milk as these packages are designed to be light resistant.

Benefits and Disadvantages

UHT processed and aseptically packaged milk benefits:

  1. Shelf Life is typically 6-12 months.
  2. Storage of the milk can be at ambient temperatures. Requires no refrigeration. Great for survival kits.
  3. Bacteria will not grow in the product until the hermetic seal on the package is broken.

Disadvantages:

  1. Average cost is higher.
  2. Sensory characteristics are different than conventionally pasteurized HTST milk. Expect a more "cooked" flavor.

A Bit About Regulatory

Any milk production plant in the United States is required to follow the lengthy federal regulations outlined in the Pasteurized Milk Ordinance. These rules include plant inspections, product testing, pasteurizer calibrations, among other rules. Grade A milk is one of the most highly regulated conventional food products. Dairy food plants are required to implement a HACCP (Hazard Analysis and Critical Control Points) plan to protect the milk products from potential process hazards.

What milk do you drink in your home?

See results

Questions & Answers

    Comments

      0 of 8192 characters used
      Post Comment

      No comments yet.

      working

      This website uses cookies

      As a user in the EEA, your approval is needed on a few things. To provide a better website experience, delishably.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

      For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://delishably.com/privacy-policy#gdpr

      Show Details
      Necessary
      HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
      LoginThis is necessary to sign in to the HubPages Service.
      Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
      AkismetThis is used to detect comment spam. (Privacy Policy)
      HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
      HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
      Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
      CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
      Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
      Features
      Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
      Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
      Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
      Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
      Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
      VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
      PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
      Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
      MavenThis supports the Maven widget and search functionality. (Privacy Policy)
      Marketing
      Google AdSenseThis is an ad network. (Privacy Policy)
      Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
      Index ExchangeThis is an ad network. (Privacy Policy)
      SovrnThis is an ad network. (Privacy Policy)
      Facebook AdsThis is an ad network. (Privacy Policy)
      Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
      AppNexusThis is an ad network. (Privacy Policy)
      OpenxThis is an ad network. (Privacy Policy)
      Rubicon ProjectThis is an ad network. (Privacy Policy)
      TripleLiftThis is an ad network. (Privacy Policy)
      Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
      Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
      Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
      Statistics
      Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
      ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
      Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)