INVESTIGATIONS ON NITROSAMINE REDUCTION IN BONELESS HAMS PROCESSED IN ELASTIC RUBBER NETTINGS

N-Nitrosamines have been found in a wide variety of rubber-containing products. Since many types of boneless hams are processed in elastic nettings made with rubber, the potential exists for forming nitrosamines. In this paper we report that addition of excess nitrite to outer surface ham and netting samples results in a significant increase in N-nitrosodibenzylamine (NDBzA). Hams were then prepared with 100 ppm ingoing NaNO₂ and compared to a standard cure of 200 ppm NaNO₂. A highly significant reduction (p <0.01) in NDBzA (31 %) was noted in those made with the lower level of nitrite. In another series of experiments, hams were stored at either −2.2C or 2.2C, for up to six or 12 weeks, with the nettings on or off the ham. The overall results suggest that the level of NDBzA increased with netting contact time. Therefore it is advisable to remove the nettings after processing.     

Temperature Dependence of Properties of Magnesium Ferrite

Magnesium ferrite varies in cell size, density, and refractive index, according to the temperature from which it was quenched, over the range 350° to 950°C. There is no evidence for long-range ordering, but the change toward a more inverse structure with decreasing temperature is toward a more ordered state. The DTA tracing shows a strong exothermic peak at 450°C. The effect of the cooling rate on the thermal contraction of magnesium ferrite is discussed.     

Firmness Control of Sweetpotato French Fry-Type Product by Tissue Acidification

The softening of a French fry-type product prepared from‘Jewel’ sweetpotatoes decreased linearly (P ≤ 0.01) when the tissue pH was incrementally lowered from ca. 6 to 3.8 prior to blanching. Tissue pH was decreased by vacuum infiltration of a series of organic and mineral acids of 0.01 to 0.4M. Firmness retention decreased when the ionic strength of the acidulant was increased by addition of NaCl. The structures of the pectic substances were affected by the tissue pH and starch hydrolysis decreased as tissue pH decreased from its normal value of ca. 6, reflecting partial inactivation of endogenous amylolytic enzymes.     

Effect of Lye Peeling Conditions on Phenolic Destruction, Starch Hydrolysis, and Carotene Loss in Sweet Potatoes

‘Jewel’ sweet potatoes were peeled in a boiling, 10% NaOH solution using the following treatments: (1) 6-min peel (6P); (2) 20-min pre-soak in water (55°C) followed by a 6-min peel (20S); (3) 30-min pre-soak in water (80°C) followed by a 6-min peel (30S); (4) 15-min peel (15P). Tissue from the heat-affected area was excised and analyzed for o-dihydroxyphenols (DP) and carotene destruction and sugar formation. The data showed that roots peeled by 6P or 20S treatments could discolor as a result of the PPO-DP reaction. Discoloration would not be found in 15P and 30S because both treatments are vigorous enough to inactivate the PPO system. Amylolytic enzymes are inactivated by all treatments except 6P. No carotenoid destruction was detected.     

High-Temperature Steady-State Creep in Rutile

The primary objective of this research was to study the interaction of point defects and dislocations in rutile at elevated temperatures. The steady-state creep rate was obtained for near-stoichiometric and vacuum-reduced compression specimens in the range 1050° to 1325°K and for stresses from 2(10⁸) to 9(10⁸) dynes per cm². For a constant stress, strain, and temperature, the activation energy for creep varies continuously from 67 kcal per mole for the near-stoichiometric condition to about 33 kcal per mole for the highest degree of reduction. The activation energy for creep in hydrogen-reduced rutile is about 80 kcal per mole and this leads to the conclusion that the rate-controlling mechanism and/or defect are not the same for hydrogen- and vacuum-reduced rutile. A model based on the interaction of piled-up dislocations on a single slip system and high-density polygon walls formed during creep is proposed to explain steady-state creep in rutile.     

ABSORPTION AND DESORPTION TO AND FROM LIQUID FILMS ON INCLINED PLANES

Two published theoretical models are examined and applied to experimental results for absorption and desorption. The system used was CO₂/H₂O and studies were made for liquid film flow down inclined planes. Experimental results give “Reduced” values of mass ransfer rates.

Interferometric studies give interfacial concentration, penetration and film depths, and take-up of carbon dioxide. In the case of desorption the interferograms are distorted by “deflections.”

All the experimental values for absorption and desorption differ from those calculated from theoretical models.

Desorption is not a mirror image of absorption, and it is approximately 75% of the transfer rate of absorption over a wide operating range.

A comparison is made of the behaviour of static pools and flowing liquid films.     

Restrictions to the use of cleanrooms for packaging pasteurised milk

The study evaluated the effect of packaging pasteurised milk inside an ISO Class 8 cleanroom and an external Class 7 antechamber. Chemical, microbiological and sensory analyses of three trials did not show evidence of improvements in the product shelf life, although the total airborne particle and the viable airborne counts were considerable higher outside the cleanroom than inside it. Post‐pasteurisation contaminations inherent to the equipments should be considered in futures studies. Therefore, the use of cleanroom technology is an operational alternative to be taken into consideration, provided that the characteristics of the whole system is compatible with the high standards of the clean air.