Evaluating Penetration Ability of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) Larvae into Multilayer Polypropylene Packages
The larvae of the Indian meal moth, Plodia interpunctella (Hübner), can invade or penetrate packaging materials and infest food products. Energy bars with three polypropylene packaging types were challenged with eggs (first instars), third instars, and fifth instars of P. interpunctella to determine package resistance at 28 °C and 65% r.h. The packing types were also challenged with two male and two female pupae of P. interpunctella under similar conditions in order to determine which package provided the greatest protection against larval penetration. Samples infested with eggs, third instars, and pupae were evaluated after 21 days and 42 days to count the number of larvae, pupae, and adults found inside the packages. Packages challenged with fifth instars were observed after 21 days to count the number of larvae, pupae, and adults inside each package. The number and diameter of the holes were determined in each package, followed by the amount of damage sustained to the energy bar. Third and fifth instars showed a higher tendency to penetrate all of the packaging types. First instars showed a reduction in package penetration ability compared with third and fifth instars. The increase in exposure time resulted in an increase in the damage sustained to the energy bars. Among packaging types, the thickest package (Test A) was most resilient to penetration by all of the larval stages. In conclusion, energy bar manufacturers need to invest more effort into improving packaging designs, creating thicker gauge films, or advancing odor barrier technology, in order to prevent penetration and infestation by P. interpunctella larvae.
Evaluation of contamination of packages containing cereal-fruit bars by eggs of the pest Indian meal moth (Plodia interpunctella, Lepidoptera) due to perforations in their polypropylene foil packaging
The quality and type of food packaging affect the level of food protection against pests. This work first evaluated the effect of package perforations on the infestation of cereal-fruit bars by the eggs of the Indian meal moth (Plodia interpunctella). We measured the differential oviposition of moths on the unpackaged bars, empty packages, bars in packages and bars in perforated packages in choice and no-choice experiments. Almost 100% of the laid eggs were laid directly on the bars when they were placed in the enclosure without packaging. A low proportion of the eggs (0.4–3%) were laid on either the empty or non-perforated polypropylene foil packages. Plodia interpunctella efficiently located and infested the bars with eggs when 5 mm package perforations were present in no-choice test. In choice test P. interpunctella preferred to oviposit on open bars than on the packaged or perforated bars. After deposition on the bars the egg hatchability ranged between 40 and 74%. For the food industry, the most significant practical conclusions of this study are that non-perforated packages provide protection against oviposition of P. interpunctella, but small perforations enable the moth to infest the resource with eggs.
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.