摘要:

AbstractThe performance of a retortable semi‐rigid aluminium container, of square shape, net capacity 330ml and with a heat sealable lid, produced in Germany by Alcan, was studied relative to parameters of filling, thermal processing and heat sealing. Tests were applied to packages containing water (275 and 295 g) and a solution of carboxymethyl cellulose (CMC) at 1.25% (295 and 306 g). The thermal processing was applied under stationary and rotary (at 8, 10 and 12 r.p.m.) conditions. Heat sealing was evaluated by visual aspect, integrity, burst resistance, tensile strength and thickness reduction. The influence of contamination (presence of water, water vapour, CMC and vegetable fat) on the heat sealing area was also examined.Rotary thermal processing has been proved more advantageous in comparison with a stationary process, mainly for a high viscosity model medium (CMC solution at 10 000 cP at 25°C), as it reduces the sterilization time to about 50%. The headspace volume measured by the destructive method indicated small variations, significant at the level of 5%, when pre‐ and post‐thermal processing values were compared. This is due to the presence of entrapped air in the test product, which is released during thermal processing. The seal resistance measured by the increase in internal pressure (burst) resistance showed average values of 26–29 p.s.i. obtained for packages containing water or CMC examined pre‐ and post‐stationary and rotary (8 r.p.m.) thermal processing. Such average values guarantee the container good performance. At the 5% level, there was no significant difference in burst resistance for the container processed with or without rotation, containing either water or CMC, at any of the filling levels analysed. Contamination of the heat sealing area, evaluated through the burst resistance, indicated the non‐existence of any significant difference at the level of 5% and the minimum value of 25 p.s.i. can be said to be satisfactory for all the treatments studied. For the two test products, at the filling levels studied, the compression resistance measured before heattreatment showed average maximum load values ranging from 84.5 to 87.8kgf (deflection varying from 4.7 to 5.0mm). After both stationary and rotary (8r.p.m.) thermal processing, the minimum crushing yield load value was around 83.5 kgf. Such values are acceptable for this k

ISSN:0894-3214    

DOI:10.1002/pts.2770080202

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA simple mathematical procedure for the estimation of water vapour transmission rate under different conditions is presented and discussed. The ASTM dynamic and gravimetric methods were used for measuring the water vapour transmission rate of four thin plastic films (PET 19 μm, PVC 16 μm, EVA 15 μm and LDPE 23 μm) under 38 different conditions of temperature and relative humidity and the corresponding permeance values were drawn. On the basis of the Clausius Clapeyron's relationship between temperature and water vapour pressure, a simple equation was derived for a rapid transformation of water vapour transmission rate data. The mathematical procedure was applied to the data collected for the four thin films and good agreement was found between observed and predicted values for the PET and LDPE films, while for the PVC and EVA films the equation developed led to an overestimate of water vapour transmission at the lower temperatu

ISSN:0894-3214    

DOI:10.1002/pts.2770080203

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper investigates the shock absorption properties of corrugated fibre‐board when impacts occur on test specimens of different sizes. In particular, the effect of two types of specimen is studied: (1) a circular specimen of the same size as the flat bottom surface of the drop hammer and (2) a rectangular specimen larger than the contact area of the impacting hammer.This study was conducted as a preliminary investigation of the significance of the cushion areas adjacent to the area in contact with the drop hammer, since this occurs in most cases in practise when packaged products rely on the shock absorbing characteristics of the corrugated fibreboard.The results show that the effect is significant and suggests that the use of traditional cushion curves for corrugated fibreboard be re‐evalua

ISSN:0894-3214    

DOI:10.1002/pts.2770080204

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe process of the transfer of a contaminant through a package made of a recycled film in good contact with a virgin film playing the role of a functional barrier is studied. The two films being made of the same polymer, the contaminant diffuses within the two layers of polymer with the same constant diffusivity. Convective transfer of the contaminant takes place through the surface of the functional layer in contact with the food, while the other external surface is impermeable to it. The effect of the coefficient of mass transfer at the packaging‐food interface on the rate of transfer of the contaminant to the food is especially studied. Dimensionless numbers are used, making the results genera

ISSN:0894-3214    

DOI:10.1002/pts.2770080205

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770080206

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770080207

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770080201

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY