Spoilage of pasteurized milk is mainly caused by the presence of organisms that either survive pasteurization (psychrotolerant spore-formers) or re-contaminate milk in the processing environment (post-pasteurisation contaminants).  Pasteurization of bovine milk by heat treating at 72°C for 15-30 seconds ensures milk quality without impairing its organoleptic and nutritional status and extends shelf life to 12-14 days at refrigeration temperatures. Nisin A is a class I bacteriocin known to inhibit gram positive bacteria and approved by the European Food and Safety Authority as a food preservative. It is commercially available as Nisaplin®, which contains a concentration of 2.5% w/w of nisin. This study examined the effect of Nisaplin® at different concentrations on spoilage of refrigerated commercial whole pasteurized milk over a period of 59 days. At a high concentration of 4 mgml-1, Nisaplin® reduced the total bacterial count below the limit of detection in the milk, and inhibition was visible for at least 14 days at 4°C. Previously isolated milk spoilage bacteria were identified using 16s rRNA gene sequencing and utilised as target indicators for bacteriocin production. Lactobacillus delbrueckii ssp. bulgaricus LMG6901, Microbacterium lacticum, and Pseudomonas aeruginosa were utilised as indicator strains in a screen of milk spoilage organisms for bacteriocin production. This resulted in identifying the putative bacteriocin producer Carnobacterium divergens, a lactic acid bacterium active against L. bulgaricus. The study concludes that Nisaplin® is effective in the reduction of microbial load and its effectiveness could be increased when combined with other preservative methods thus forming an extra hurdle in the milk.

Fermentation is the oldest traditional method in order to protect against spoilage and pathogenic microorganisms. Thermal treatment, pH and water activity lowering and preservative addition other food preservation techniques that are commonly used. Although, as preservatives, many improved antibiotic and chemical agents have been gained, there are some other factors such as rapid resistance to antibiotics used in bacteria, in order to limit their use in food, to be found dimensions of threatening human health of the chemical protection and to cause allergic reactions. Recently, studies on bacteriocins that are produced by the safe bacteria, such as lactic acid bacteria, contain no toxic and adverse effects for human consumption have gained sudden intensity in accordance with the request against consumers in developing microbiologically safe and minimal processed food. There are some important effects using of bacteriocins accepted the new generation of antimicrobial agents as food preservatives such as extension of shelf life, reducing of the use of chemical preservatives and the economic loss caused degradation by microorganisms. Nisin, defined as GRAS (Generally Recognized as Safe) by FDA and named the E234 code 'Nisin-protective' or 'natural protective' located in the food additives list, first used in 1988 as a natural preservative by prohibiting of antibiotics using in food in the US. Nowadays in more than 50 countries, there have been more successful implementation of the nisin protected up the food from milk and dairy products to canned foods many food products

Bu çalışmada farklı konsantrasyonlarda (%0,2, %0,4 ve %0,8) hazırlanan nisin solüsyonlarının levrek filetolarının soğukta ve vakum paketlenerek depolanması esnasında renk değişimleri üzerindeki etkileri incelenmiştir. Panelistler tarafından gerçekleştirilen duyusal analizlerde (çiğ ve pişmiş olarak) levreğin raf ömrü I. denemede kontrol grubunda 6 gün, nisin uygulanan gruplarda ise 8 gün olarak; II. denemede ise kontrol grubunda 12 gün, nisin uygulanan gruplarda ise 14 gün olarak belirlenmiştir. Nisin uygulanmasının balık etinin doğal kokusu ve aroması üzerine olumsuz bir etkisi gözlenmemiştir. Panelistler tarafından kontrol grubuna göre daha çok tercih edilmiş olan nisin uygulamasının levreğin raf ömrünü 2 gün uzattığı tespit edilmiştir. Elde edilen sonuçlar, filetolanmış levreğin tek başına nisin ile muamelesinde (Deneme I) ve vakum paketleme ile nisinin kombine kullanımları (Deneme II) sonucunda rengini daha iyi koruduğunu, 4±2°C’de deneme I’ de 12 günlük ve deneme II’de 18 günlük depolamada daha iyi renk sonuçları ile kontrol grubundan daha iyi tüketici algısı oluşturmuştur. Sonuç olarak nisin uygulaması, filetoların renk stabilitesi üzerine pozitif etki yapmıştır. Mevcut çalışma sonucunda elde edilen bulgular, su ürünlerinin kalitesi ve kontrolü üzerine yararlı bilgiler içermektedir. İnsan sağlığı üzerinde olumlu etkilere sahip alternatif doğal bir koruyucu olarak nisinin kullanımı hakkında gıda sektörü ve tüketicilerin bilgilendirilmesinin ekonomik ve sosyal bir yaygın etki sağlayabileceği öngörülmektedir.