EVALUATION OF ISOMALT AND HYDROGENATED STARCH HYDROLYSATE IN SUGARLESS CARAMEL POPCORN1

Five formulations of sugarless caramel popcorn sweetened with different proportions of hydrogenated starch hydrolysate and isomalt were developed. Control and test products were evaluated for changes in physical, chemical and sensory properties over a 3‐month storage period at 33C and 50% humidity. Moisture content and water activity values increased for all products, but color values did not change with time. Texture compressibility measurements were highly correlated with liking of texture values gathered from a consumer study. The fonnula with 100percnt; isomalt was liked significantly more by consumers than the other formulas.     

A linear dynamic system approach for cattle herd optimal shaping

The time evolution of a herd of cattle is modelled as a linear dynamic system with slow time variation in model parameters. From this model, the optimal policy for the herd shaping is established, allowing the minimal initial cost with cattle acquisition and the maximal farm resources utilization in the steady state. The same methodology can be employed in several different production schemes, with different constraints and different objective functions. The optimization problem is formulated as a convex programming one, being solved with efficient algorithms, while keeping guaranteed convergence to the global optimum. This methodology is simpler than the dynamic programming optimization method.     

MACRODONTIN, A NEW PROTEASE ISOLATED FROM FRUITS OF PSEUDANANAS MACRODONTES (MORR.) HARMS (BROMELIACEAE)

A cysteine proteinase was isolated from immature fruits of Pseudananas macrodontes (Morr.) Harms, a species taxonomically close to pineapple grown in the northeast of Argentina. The protease is active at pH 7.0 to 10.5, and rather unstable at temperatures over 45C. Crude extracts were purified by acetone fractionation followed by chromatofocusing at the pH range 4.5 to 6.5. Two main proteolytic fractions were obtained: fraction I (M_r= 20.6 kDa, pI = 5.9) and fraction II (M_r= 19.3 kDa, pI = 5.3), both homogeneous by gel-filtration and SDS-PAGE criteria. This new plant protease (“macrodontin”) could be valuable in processes carried out in neutral-weak alkaline media. The thermal behavior of the crude enzyme is also a useful property, since it could be easily inactivated in foodstuffs by heating 10 min at 75C. Comparison of macrodontin and alcalase proteolytic behavior on soy concentrates is presented.     

DETERMINATION OF DIFFERENT VOLATILE BASE COMPONENTS AS QUALITY CONTROL INDICES IN FISH BY OFFICIAL METHODS AND FLOW INJECTION ANALYSIS

Flesh concentration of Trimethylamine Oxide‐Nitrogen (TMAO‐N), Trimethylamine‐Nitrogen (TMA‐N) and Total Volatile Base Nitrogen (TVB‐N) are the most studied parameters used as indices of spoilage in fish and fishery products. In the present work, the official methods to determine TVB‐N, TMA‐N and TMAO‐N were compared with the Flow Injection Analysis (FIA) technique using three different fish species over their storage in melting ice for a period of 16 days. There was a good correlation between determinations made using official and FIA methods with no apparent significant differences. FIA thus appears to be a suitable method for TMAO‐N, TMA‐N and TVB‐N in fish extract and the use of this system is much faster and simpler than the official methods for determination of these parameters. On the other hand, the individual concentrations of TMAO‐N, TMA‐N and TVB‐N were not found to represent reliable indices of spoilage in fish, which had been frozen and thawed and then presented in chilled format.     

LIPID CHANGES IN FROZEN STORED FILLETS FROM PRE- AND POSTSPAWNED HAKE (MERLUCCIUS HUBBSI MARINI)

The lipid composition of frozen stored fillets from pre‐ and postspawned hake was studied. The total lipid (TL) content in the chloroform/methanol extract from unfrozen postspawned hake was four times higher than that of prespawned fish. After freezing, the TL content of postspawning hake muscle remained unchanged whereas the TL extracted from prespawning fish muscle increased about 90%. The TL extractability of muscle from fish in both different gonadal conditions was not affected by frozen storage. Lipolysis in frozen stored fillets from prespawned hake occurs principally by hydrolytic action on phospholipids (PL), and phosphatidylcholine was the main PL hydrolyzed. Triacylglycerols were the main substrates hydrolyzed in frozen stored fillets from postspawned hake. Freezing and frozen storage affected polyenoics and n‐3 fatty acids (FA). The decrease in the contents of n‐3 FA in fillets from postspawned hake was lower than that observed in fillets from prespawned fish.