Aktuelle Themen

Aktuelle Themen

Aktuelle Themen


Münevver Yücebay, G. Seval Karslı, Birce Mercanoglu Taban, S. Aykut Aytaç, H. Barbaros Özer, Ayşe Gürsoy, Mustafa Akçelik
The effects of autochthonous probiotic strains of Lactobacillus brevis and ­Pediococcus pentosaceus on Staphylococcus aureus during pro­duction and ripening of white-­pickled cheeses
Auswirkungen von autochthonen probiotischen Stämmen von Lacto­bacillus brevis und ­Pediococcus pentosaceus auf Staphylococcus aureus bei der ­Herstellung und Reifung weisser Käse in Salzlake

The effects of two autochthonous probiotic strains of Lactobacillus brevis BG18 and ­Pediococcus pentosaceus BH105 were investigated on the growth of Staphylococcus ­aureus. S. aureus counts were monitored separately during production and ripening of white-pickled cheeses by BAM’s 5-tube MPN method. Pasteurized milk used for cheese production with either 1 % Lb. brevis or P. pentosaceus, was artificially contaminated with S. aureus to the mean levels of 6.252 log MPN/mL and 5.952 log MPN/mL, respectively. The study was also carried out with control group cheeses produced without ­adjunct culture. Each positive tube of MPN method was confirmed by PCR amplification of a 400 bp region of the nuc gene. As a result, Lb. brevis BG18 could reduce S. aureus count by 0.4 and 0.7 log units separately during the production (22nd hours) and ripening (92nd day), respectively, when compared to control group cheeses. Whereas P. pento­saceus BH105 could sharply reduce S. aureus counts by 1.8 log units during ripening (92nd day), when compared to control group cheeses. As a result, the present study ­demonstrates the potential use of these autochthonous strains as adjunct cultures in white-pickled cheese production to prevent S. aureus growth which is a great point of importance in respect of food technology as well as food safety.

Martina Ludewig, Julia Höhne, Peggy G. Braun
Mikrobiologische und sensorische Qualität von Lachserzeugnissen aus dem Leipziger Einzelhandel
Microbiological and sensory quality of salmon products from retail in Leipzig

Kaltgeräucherter und Graved Lachs sind leicht verderbliche Lebensmittel, die beim Verbraucher sehr beliebt sind. Im Jahr 2017 wurden am letzten Tag des Verbrauchsdatums von 15 Proben kaltgeräuchertem und 10 Graved Lachs aus dem Leipziger Einzelhandel die mikrobiologische und sensorische Qualität sowie der pH-Wert geprüft. Die mikro­biologischen Untersuchungen umfassten die Parameter aerobe mesophile Gesamtkeimzahl, Milchsäurebakterien, Enterobacteriaceae, Listeria (L.) monocytogenes und sulfitreduzierende Clostridien. Für Räucherlachs wurde eine mittlere Gesamtkeimzahl von log10 4,50 und für Graved Lachs von log10 5,34 KbE/g festgestellt. Der Medianwert für die Anzahl der Milchsäurebakterien lag bei log10 4,46 (Räucherlachs) und log10 5,21 KbE/g (Graved Lachs), für die der Enterobacteriaceae bei log10 3,60 (Räucherlachs) und bei log10 3,52 KbE/g (Graved Lachs). L. monocytogenes wurde in je 2 Proben Räucher- und Graved Lachs und sulfitreduzierende Clostridien in einer der Graved Lachsproben festgestellt. Für die Differenzierung der Hauptkeimflora wurde die Maldi-TOF MS angewendet. Lactobacillus curvatus, Carnobacterium maltaromaticum, Brochothrix thermosphacta, Candida zeylanoides und Serratia spp. wurden am häufigsten nachgewiesen. Die sensorische Untersuchung erfolgte auf der Grundlage des DLG-Punkteschemas (DLG, 2016). Danach erreichten jeweils 44 % der Proben Punktzahlen von 4,8 bis 4,0 bzw. von 3,9 bis 3,1. 84 % der Proben wiesen Abweichungen im Geschmack auf, wobei diese bei 16 % der Proben deutlich waren. Lediglich eine Räucherlachsprobe zeichnete sich durch eine einwandfreie Qualität aus und wurde mit 5 Punkten bewertet. Die pH-Werte der Lachsproben schwankten zwischen 5,70 und 6,11. Die Ergebnisse zeigten, dass kaltgeräucherter und Graved Lachs mit verschiedenen Verderbniskeimen belastet waren. L.-monocytogenes-Kontaminationen können nur durch ein kontinuierliches Monitoring auf allen Stufen der Produktion und der Endprodukte vermieden werden.

11122
Determination of Seasonal Distribution of Aflatoxin M1 Level in Cheese Production
Bestimmung der saisonalen Verteilung des Aflatoxin M1-Gehalts in der Käseproduktion

The aim of this study was to determine the Aflatoxin M1 (AFM1) quantities in raw milk samples and cheese samples produced from the same lot. The samples were obtained from six dairy plants in four different seasons. AFM1 amounts of the samples were assessed by a Reverse-Phase High Performance Liquid Chromatography (RP-HPLC) ­device with fluorescence detector, using a preliminary immune affinity column (IAC) for post-column derivatization and these values were compared with legal limits. Average of AFM1 values of raw milk samples were determined to be 41.9 ng/l, 31.3 ng/l, 68.5 ng/l and 92.0 ng/l in spring, summer, autumn, and winter, respectively. 54.2 % of the investigated milk samples exceeded legal limits. AFM1 concentrations were higher during the autumn and winter. Average values of AFM1 in cheese samples were determined to be 92.7 ng/kg, 72.3 ng/kg, 190.6 ng/kg and 255.8 ng/kg in spring, summer, autumn, and winter, respectively. AFM1 was at levels of 1.25 to 5.18-fold higher than those presented in the raw milk used for the cheese production. Based on the ad­missible limit, 16.7 % of the cheese samples were shown to have exceeded this valid maximum limit value. Consequently, it was found that seasonal change had a signi­ficant effect on the amount of AFM1.

Guangpu Zeng, Wenbiao Wu, Wei Huang
Evaluation of nutritional and other ­functional qualities as well as dietary safety of pumpkin leaves
Bewertung der ernährungsphysiologischen und anderen funktionellen ­Eigenschaften sowie der Lebensmittelsicherheit von Kürbisblättern

Currently there is a great demand of finding health food resources in the world. ­Presently, large quantities of pumpkin leaves are underutilized. Their potential of being exploited as a health food resource was therefore evaluated in this study. The experimental results indicated that pumpkin leaves were rich in proteins, all essential amino acids, most vitamins (including B1, B2, B3, B5, B6, B11, C, A, E and K) and most essential mineral nutrients (including K, Na, P, Ca, Mg, Fe, Zn and Cu) and that they contained significant amount of other functional compounds including polyphenols, alkaloids, saponins and phytates which contributed significantly to the antioxidative capacity of pumpkin leaf extract. A diet with over 90 % source of dietary proteins attributed to pumpkin leaves can be safely consumed throughout lifetime. Comparing with the growth curve of mice fed on a conventional diet, that of mice tested on the pumpkin leaf diet was identical, but their lifespan was significantly longer. Pumpkin leaf powder was therefore concluded to be nutritious and safe for consumption and rich in some other components beneficial to health. These illustrated the potentiality of pumpkin leaves as a valuable health food resource.