Search

With the introduction of the fast autosampler, the rules on how to perform splitless injection should have been revisited: the fast autosampler releases the sample liquid as a band that is no longer nebulized by solvent vapors as in previous injection techniques. In empty gooseneck liners, the sample liquid is shot to the bottom of the injector and jumps around in a largely uncontrolled manner. Visual experiments showed that the liquid is partially rejected. Another portion passes by the column inlet into the column attachment region, while the last part may directly enter the column. The impact on chromatography was investigated by using a mixture of n-alkanes: the higher boiling components passing by the column entrance into the zone of the column attachment were largely lost, i.e., were discriminated against the volatile components. It was concluded that empty gooseneck liners are not suitable for injection by fast autosamplers.

Byline: Koni Grob (1), Maurus Biedermann (1), Sandra Biedermann-Brem (1), Anja Noti (1), Daniel Imhof (1), Thomas Amrein (1), Anton Pfefferle (2), Diego Bazzocco (2) Keywords: Acrylamide; French fries; Potatoes of low reducing sugar Abstract: In collaboration with cooking experts, the preparation of French fries in oil and in ovens was optimized, aiming at optimum culinary quality combined with a minimum acrylamide content. French fries with 40--70 ug/kg acrylamide were consistently produced, i.e. with 5--10 times less acrylamide than currently normal. The raw potato should contain little reducing sugars, i.e. be of a suitable cultivar, and storage at temperatures below about 10 degC must be avoided. After cutting and elimination of the fines, the potato is immersed in standing cold or boiler-warm water for some 15 min in order to extract asparagine and sugars from the surface without washing out the starch. Pre-frying in oil (ca. 140 degC for 2.5 min) improves crispiness. Frying should occur at an initial oil temperature of about 170 degC, adding some 100 g potato/l oil. Since acrylamide formation increases exponentially towards the end of the process, the most important factor to keep acrylamide contents low is the determination of the proper end point of the frying process. French fries should be crispy with slight browning of the tips to achieve the typical flavor, but without general browning. Preparation in the oven, starting from frozen prefabricates, requires temperatures of around 190 degC or 220 degC, depending on whether or not the air is circulated. The proper determination of the end point is again the most critical step. Author Affiliation: (1) Official Food Control Authority of the Canton of Zurich, P.O. Box 8030, Zurich, Switzerland (2) Belvoirpark Zurich, School of Hotel Management*HF, Seestrasse 141, 8002, Zurich, Switzerland Article History: Received Date: 31/03/2003 Online Date: 02/08/2003

Although classical split and splitless injection is more than 30 years old, we only start to understand the vaporization process in the injector. Solvent evaporation determines much of the process and is the first obstacle to overcome. Videos recorded on devices imitating injectors showed that sample (solvent) evaporation is often a violent process which is poorly controlled and might well explain many of the puzzling quantitative results often obtained. We do not adequately take into account that two vaporization techniques are in use. Partial solvent evaporation inside the syringe needle (optimized as 'hot needle injection') produces thermospray: the sample liquid is nebulized upon leaving the needle. The resulting fog is rapidly slowed and moves with the gas. Solute evaporation largely occurs from microparticles suspended in the gas phase. Empty liners are most suitable. Fast autosamplers suppress vaporization in the needle, i.e., nebulization, and shoot a band of liquid into the chamber that must be stopped by a packing or obstacles suitable to hold the liquid in place during the 0.2-5 s required for solvent evaporation. Solute evaporation largely occurs from the surfaces onto which the sample is deposited. Insights into these mechanisms help optimize conditions in a more rational manner. Methods should specify whether they were optimized and validated for injection with thermospray or band formation. The insights should also enable a significant improvement of the injector design, particularly for splitless injection.

Recycled paperboard contains hundreds of non-evaluated or even unidentified substances that could endanger human health if they turn out to be highly toxic. It seems as unrealistic to evaluate each of them as it is to phase out the use of the problematic ones or sort out the papers and boards introducing them into the recyclate. Therefore, measures should be taken that generally reduce migration into food, such as functional barriers or functional sorbents. A general approach is used for the recycling of plastics, particularly poly(ethylene terephthalate), PET: as not every potential contaminant can be regulated, a pragmatic approach is applied, for PET mainly on the required decontamination efficiency. Criteria are required on the required efficacy of the measures to be taken. Recycled paperboard is used for various types of food contact: mostly contact is through the gas phase (evaporation and recondensation), often indirect through other layers (e.g. internal bags or for transport boxes), seldom in wetting contact. Numerous factors have to be considered. For typical folding boxes and at least strongly dominating gas phase contact, it was proposed that no more than 1% of each contaminant in the recycled paperboard should enter the food. The efficiency of the measures required to comply with this criterion depends on the application. The three main measures are reviewed with regard to this criterion: (i) internal bags with an incorporated functional barrier (successfully used for some time), (ii) a barrier layer on the internal wall of the box (for which the design of the closures might be most critical) and (iii) functional sorbents added to the paperboard (for which the sorbent capacity is critical). For transport boxes, commonly of corrugated board (quantitatively the most important use of recycled paperboard in food contact), an adjusted or different criterion is needed. [ABSTRACT FROM AUTHOR]

The use of recycled paperboard for packaging dry foods is in the interest of sustainability of resources, but in most applications, the food must be protected against contamination, such as by a functional barrier on the internal surface of the paperboard box. After application, the paperboard is usually stacked or reeled before making boxes. During this period, the food-contact surface of the barrier layer is in contact with the outer side of the paperboard, which may result in set-off and subsequent contamination of food. A method is described for the determination of this path of migration, based on the taped format also used for the measurement of the barrier efficiency. Recycled paperboard containing the three surrogate substances n-heptadecane, 4-methyl benzophenone and dipropyl phthalate was taped to the food-contact side of the barrier layer. Pressure onto the test packs did not seem to be a relevant parameter. After periods of interest, a piece of the paperboard with the barrier layer was extracted and analysed for the surrogate substances. Another piece may be brought into contact with silicone paper to simulate the transfer to food. After 2 weeks at 60°C (simulating about 1 year at 25°C), set-off and the transfer to the silicone paper exceeded 1% for all barrier materials tested, but after 6 weeks at 40°C (around half a year at 25°C), set-off remained below 1% for all barrier layers except a multilayer with polyethylene on the food-contact surface. The preliminary conclusion is that set-off should be taken seriously, but may be kept low enough to provide sufficient protection of the packed food. [ABSTRACT FROM AUTHOR]

Internal bags with a functional barrier are a promising solution to render recycled paperboard acceptable for food packaging. Producers and users of such bags as well as control authorities need a tool to evaluate whether a bag satisfies the requirements of safety. In the previously proposed methods, the criterion focused on the permeability of the barrier layer. This neglected the influence of absorption or adsorption of the substances in the paperboard and the plastic of the bag. To take these contributions into account, it was proposed to change the criterion and use the percentage of the amount of (surrogate) substances in the recycled paperboard that passes into the food. This paper explains this, in particular how the method better reflects the reality in a pack of food. Firstly, donors should be prepared from recycled paperboard, as the behaviour differs from that of paper. Secondly, absorption into the paperboard seems to be a slow process. It was noted that freshly added surrogate substances were easily extracted by methyl tert-butyl ether, but the extraction yield decreased during storage over some weeks. To catch this reality of the substances in the paperboard, donors need to be conditioned before use. Finally, absorption in the paperboard may depend on the concentration, which prompted a further reduction of the amounts of the surrogate substances used for testing. It turned out that usually the hydrocarbon (C17) determines the barrier efficiency; triethyl citrate is no longer used, as it was never a relevant surrogate. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Internal bags with an integrated functional barrier are a promising solution to avoid food contamination from recycled board packaging. The efficiency of the barrier should be measurable by a simple test that appropriately reflects reality. A previously described test, involving four surrogate substances on a donor paper and silicone paper as a receptor in a taped format (Packag Technol Sci. 2014; 27:713-726), was amended to take into account findings on absorption in the internal bag and the board. The combined effects on migration are now calculated as the percentage of the surrogate substances detected in the receptor compared to the amount in the donor. Because recycled paperboard has absorption properties different from paper, and the pressure onto the barrier depends on the concentration rather than the amount, now recycled paperboard is used as donor matrix. The concentration of the surrogate substances in the donor was further reduced. Donors need to be conditioned before use. Three silicone papers and Tenax® as receptors gave similar results. The comparison with foods showed that the migration into silicone paper was higher than that into bread crumbs, but lower than into rice and polenta by roughly a factor of 2, presumably because of the low mass. A detailed description of the method is provided and further validation of various technical aspects. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]