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By Bob Sperber, Plant Operations Editor | 05/21/2010
Taylor says reduced time-temperature profiles impart a flavor boost at some expense to shelf life. After about two weeks, Taylor admits the taste and complexity of his product begin to break down and taste "like anyone else's store-bought milk, which never changes – it tastes just as bland after three weeks as it does the day it was bottled."
Fighting words? Maybe. The consensus of Big Dairy seems to be that minimal processing imparts no discernible quality benefit.
Chris Galen, spokesman for the National Milk Producers Federation (NMPF), chalked-up taste differences to a consumer "placebo effect" in a National Public Radio report last December. "If you're paying six or seven or eight dollars a gallon versus $3, you might think it tastes better simply because it cost more," he said. But the same broadcast had shoppers sampling Snowville's minimally processed milk, with one likening it to the milk her mother used to get "from a farm near us when we were growing up … it's really good." Taylor employs more than 24 in-store samplers and says a steady stream of feedback and letters confirms the taste advantage.
Why do large processors gravitate toward higher-heat processes? Perceptions of safety, consistent quality, shelf-life and distribution range all play into current processing methods:
So far it appears that no major dairy processor has moved to minimize pasteurization profiles. On the contrary, many continue to explore still-higher-heat processes using ultrapasteurized or ultra-high temperature (UHT) milk processed at approximately 283°F for four seconds. UHT milk in combination with aseptic packaging provides more than six months of non-refrigerated shelf life.
AGC's Tholl notes that HTST milk "tastes better than UHT milk, which has never been widely accepted in America due to its burnt flavor," which owes to caramelized sugars. "It's been accepted by European consumers, but they've never had the consumption levels of the U.S."
Taylor, predictably unimpressed with UHT, notes it imparts "millions of times more heat effect than HTST," which itself is less than ideal for preserving the flavor of milk, he says.
The latest rapid heating and cooling advances, however, are aimed at narrowing the gap between UHT and HTST milk. For example, direct steam technologies are said to now produce UHT milk "that is virtually indistinguishable from pasteurized [HTST] product in terms of flavor and color," says SPX' Snow.
If it's clear what Taylor is doing, how he's doing it may need a bit of demystifying. The mechanical processes in Snowville's processing room are all conventional, including items such as AGC plate heat exchangers and Waukesha Cherry-Burrell sanitary valves and pumps. Taylor says the greatest single factor in reducing his time-temperature profile is the fact that it's scaled-down with, for example, 1-in. piping instead of the 4-in. pipes a larger dairy would use.
Snowville's process instrumentation and controls are similarly conventional but scaled-down. Most of the dairies Taylor worked on maintain six to 10 control loops on their pasteurization and clean-in-place systems, although one leading national processor's state-of-the-art system topped 20 control loops linked to centralized supervisory controls.
Today, his little operation uses two standalone controllers: one to control the flow of hot water through the heating section and another for temperature control. A dedicated, programmable controller manages the HTST process, and variable frequency drives run most motors pumps and agitators as well as the separator and homogenizer used for ice-cream mix.
Controlling process variability between Snowville's much-tighter range of upper and lower limits, then, owes much to the scale of the process. Still, high-volume dairies might find value in considering the potential value in tweaking their own parameters for greater process efficiency and product quality.