In a simple, rapid isocratic HPLC method sugars and organic acids were separated on an Aminex HPX-87 column in the H+ form and detected using ultraviolet and refractive index detectors in series. Sugars (lactose, glucose and galactose) and acids (erotic, citric, pyruvic, lactic, uric, formic, acetic, propionic, butyric and hippuric) were identified by retention times. This method affords a simple technique for monitoring starter culture activity and following quality changes during cheese maturation.

Cooling freshly formed Cheddar cheese requires close control for uniform and consistent flavor. Cheese in 18-kg blocks collected after pressing, at 30-35°C was used. Samples were cooled rapidly to 12 25°C as small pieces individually vacuum-wrapped at a local production site. The extent of proteolysis, total acidity, pH, lactose and organic acids was quantified after storage at these temperatures. Theoretical and empirical equations describing the influence of time and temperature on these chemical indicators were developed through nonlinear statistical methods. The kinetic expressions were applied to generate recommendations for the cooling rate and subsequent aging temperature of Cheddar cheese blocks.

A method based on change in proton precession frequency with temperature was compared with temperature measurement by T1-weighted imaging. Temperature maps of a gel, and of cooked and raw red potatoes were developed during heating from 20 to 60ЊC. To measure change in proton precession frequency, a steady state free precession sequence allowed 2-dimensional acquisitions in 8 sec with spatial resolution of 0.88 mm 2 . Temperature resolution with chemical shift imaging, ranged from 0.3 to 3ЊC, decreasing with increasing temperature due to a decrease in signal to noise ratio. The difference by this method and thermocouples was Ͻ 5ЊC. T1-weighted spin-echo images showed artifacts due to an inhomogeneous T1 distribution within the potatoes, indicating chemical shift was more reliable for inhomogeneous foods.

The potential of an immersion system of glucose oxidase (GOX, 1 unit/ml) and catalase (CAT) added to 4% w/v glucose in artificial seawater was determined for on-board shrimp preservation. Fresh shrimp were frozen, radiation-sterilized, thawed by adding artificial seawater and inoculated with Pseudomonas fluorescens (lo4 CFU/g shrimp).Samples were stored at 1°C and treated after 24 hr or left as controls. Changes in shrimp and solution were monitored by total plate counts, ammonia and total volatile nitrogen. Solution discoloration due to shrimp melanosis was followed spectrophotometrically. Microbial lag phase was extended si: 5 d and after 14 d, GOX/CAT had reduced browing by 180% and inhibited ammonia and total volatile nitrogen production. Due to increase in nitrogen compounds, the enzyme solution should be replaced after 14 days.

Magnetic Resonance Imaging (MRI) was used to obtain 2-dimensional temperature maps in potatoes undergoing aseptic processing. The change in precession frequency of protons served as the temperature indicator. The larger particles (6.9 and 3.84 cm 3 ) showed a ∆T (T surface -T center ) of up to 22±0.4°C 45s after exiting the heat exchanger with the ∆T (T outlet -T inlet ) of the carrier fluid in the heat exchanger at 30 to 45°C. No ∆T was measured between the center and the surface of particles <2.05 cm 3 pumped at <22.7 L/min. The average fluid to particle convective heat transfer coefficient (h fp ) for the heat exchanger and holding tube was calculated using a finite element method. The hfp was from 600 to 2500 and >3000 W/m 2 °C for the large (6.9 cm 3 cubes) and smaller particles respectively.