Special 34 1/2013 Haltbarmachen Preserving Foto: Tom Sawyer/pixelio.de cannot be inactivated. Botolinum toxins aren‘t heat-resistant. Heat-re-sistant toxins particular-ly include those of bac. cereus and staphylococus aureus. Sterilisation Partial or complete sterilisation is done in hermetically sealed cans. Depending on the efficien-cy of germ elimination achieved by the heat treatment, preserved products are categorized as semi, three-quarter and fully preserved products as well as tropical pre-served and shelf-stable products. Table 1 (page 32) shows a catego-risation of canned sausages after heat treatment and their shelf lives. Fully preserved products treated in an autoclave are usually treat- ed at temperatures around 120° (117°-130°C). Kettle preserved cans are sterilised at temperatures around 100°C. In order to ensure that the steri-lisation effect of each heat treat-ment cycle of a product can be compared, the F-value was intro-duced as a measure for the de-gree of germ elimination. To this end a temperature of 121.1°C (250°F) and a z-value of 10°C have been established as basic values. F = 1 min or F = 5 min me-ans that a temperature of 121.1°C for a period of 1 minute or 5 minu-tes respectively has been applied. Fully preserved products are ste-rilised at an F-value of 5 to 8 min. Image 1 shows the individual sta-ges of the sterilisation process and the temperature development in the container. The process is computer controlled. After a par-ticular 2012_AZ_Feuer_92x65mm_quer_2c_+XCyclone_Fettnebel_RZ_neu_Reven_AZ_Skelett_92x65mm_RZ_EN 16.11.12 15:38 Seite 1 Ka n a l a b s c h e i d e r Putzt Fettnebel und Feuerteufel weg! 0 - F-value is set, the process 3 7 runs fully automatically. When 3 - 2 a certain elimination rate (lethal 4 0 rate) is achieved, the process 7 ) 0 switches from holding time to de-crease ( 9 and finally to completion 4 + of the sterilisation process. Fully : . l preserved products have a shelf Te life of four years and more. Kettle · r e preserved products usually have g i a shelf life of one year. A storage n i e temperature of 10°C is advisable r t f u for these types of products. L ® N Changes of heated products E V E During heat treatment of meat and R meat products, different types of Schleusener changes occur in the product. This includes denaturation and heat coagulation of myofibrilar and sar-coplasmatic proteins. Collagen is transformed into gelatine. Enzyme inactivation results from a change in the protein structure followed by caramelisation due to carbo-hydrates. Fats are melted out. They are changed by means of hydrolytic separation and oxidation. During long-term storage, hydrolytic by-products may form, which cause a sour-soapy taste. Vitamins are destroyed – especially those of the B-complex. Two thirds or more of Vitamin B1, which particularly oc-curs in pork, can be destroyed. Vitamin A and ribovlavin are dest-royed by up to 20 % (Janetschke). During long-term storage of pre-served food, a decrease of aroma and taste can be observed. Imper-fections, which at the beginning were hardly perceivable can be-come more significant. In the field of preservation me-thods, there are several new re-search papers available and the methods have also been applied in practice. They are aimed at provid-ing a method that ensures quick inactivation of enzymes and micro-organsims in foodstuff and at the same time provides for a gentle treatment of the product. Examp-les that should be mentioned in-clude: ISI-technology (improved steam injection), Ohmic Heat Treat-ment (OH), Ultra-high-pressure treatment (HHP), Pulsed Electric Fields (PEF), Microwave Assisted Thermal Sterilisation (MATS) and heat treatment by means of radio frequencies (RF, see e.g. www.- radiofrequency.com) Tests on liquid (e.g. milk), pumpable (e.g. sausage meat) and ground (e.g cooked ham and bratwurst) products have been conducted. Summary The current state in heat treatment technologies and equipment, further-developments in the field of container materials as well as the development and improve-ment of pasteurisation and steri-lisation conditions have enabled producers of preserved food to offer high-quality and safe prod-ucts. Heinz Sielaff and Heinz I n t e r e s s i e r t a n e i n e r Vo r f ü h r u n g i m W e r k ? w w w. r e v e n . d e / f e t t n e b e l -bessereProzesshygiene -ölfreieMaschinen -saubereAbluftkanäle -geruchsfreieFortluft -selbstreinigende CYCLONE-Abscheider -hoherBrandschutz -allesausEdelstahl REVEN® X-CYCLONE® auf, z. B. des Fleischgefüges. Es kommt in der Folge zur Dena-turierung und Hitzekoagulation der myofibrillären und sarkoplas-matischen Proteine. Kollagene werden zu Gelatine umgewan-delt. Die Enzyminaktivierung er-folgt durch Veränderung der Pro-teinstruktur. Es tritt eine Karamelisierung ein, an der Kohlenhydrate beteiligt sind. Fette werden aus- bzw. ab-geschmolzen. Sie werden durch hydrolytische Spaltung und Oxi-dation verändert. Bei Langzeit-lagerung können hydrolytische Spaltprodukte auftreten, die ei-nen sauer-seifigen Geschmack hervorrufen. Es entstehen Ver-luste an Vitaminen, vor allem des B-Komplexes. Bei Vitamin B1, das insbesondere in Schwei-nefleisch vorhanden ist, können sich Verluste von bis zu 66 % und mehr ergeben. Vitamin A und Riboflavin werden zu je 20 % zerstört (Janetschke). Bei Langzeitlagerung von Kon-serven wird ein Abflachen des Aromas und Geschmacks be-obachtet. Zunächst kaum wahr-nehmbare Mängel können stär-ker hervortreten. Auf dem Gebiet der Konser-vierungstechnologie gibt es ver-schiedene neue Forschungsar-beiten und bereits auch Anwen-dungen, vor allem im Ausland. Sie dienen dem Ziel, im Lebensmittel vorhandene Enzyme und Mikro-organismen in möglichst kurzer Zeit bei weitgehender Schonung der Inhaltsstoffe zu inaktivieren bzw. ab-zutöten. Zu nennen sind hier: ISI-Technologie (verbesserte Dampfinjektion), Ohm‘sche Er-hitzung (OH), Ultra-Hochdruck-behandlung (HHP), Gepulste elektrische Felder (PEF), Mikro-wellengestütztes Sterilisieren im Autoklaven (MATS) und Erhit-zung mit Radiofrequenzen (RF, vgl. z. B. www.radiofrequency. com). Es wurden Versuche an flüssigen (z. B. Milch), pumpfähi-gen (z. B. Fleischbrät) und stü-ckigen (z. B. Kochschinken und Bratwurst) Gütern durchgeführt. Resümee Der Stand der Technik und Tech-nologie der Hitzebehandlung, Verbesserungen auf dem Gebiet das Behältermaterials sowie die Entwicklung und Optimierung der Pasteurisations- und Steri-lisationsbedingungen sind die hauptsächlichen Fortschritte, die Konserven herstellende Betriebe in die Lage versetzt haben, qua-litativ hochwertige und sichere Erzeugnisse zu produzieren. Ein besonderes Augenmerk richten die Unternehmen der Fleischver-arbeitung auf neue, die Inhalts-stoffe schonende Konservie-rungsmethoden. Heinz Sielaff und Heinz Schleusener
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