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Abstract
Proteases hold an important position in today's world commercial enzyme market. Among various microbial producer genera, Bacillus is leading the commercial protease production. However, industry is still actively looking for new microbial protease producers with distinctive properties. Therefore, this study was undertaken for the evaluation of protease production by Bacillus megaterium DSM 32 strain in terms of its protease productivity, calculation of various production kinetics, partial characterisation of the enzyme, and modelling the protease production process. As results, the highest protease activity, specific cellular protease production rate, and protease productivity were calculated as 255.42 U mL−1, 36.2514 U g−1, and 16.1313 U mL−1 h−1, respectively, in shake flask fermentations. Partial characterisation studies showed that the enzyme has 45 °C and pH 8 as optimum working conditions, and its activity increased by 24% with the addition of 5 mM Mn+2 to the reaction medium. Additionally, the enzyme showed high stability and kept almost full activity in a cell-free medium for 20 days at 4 °C. Furthermore, modified Gompertz model provided the best fit in describing protease production with the lowest error and high fit values.
Abstract
Poultry processing industry produces large quantities of by products (skin, bone, and feather) that contain significant amounts of protein. The source of gelatine is of great concern for some societies including Muslims, Hindus, and Jews as gelatine is mostly obtained from porcine sources. In the present study, gelatine was obtained from chicken skin and some quality and functional features were evaluated in comparison with commercial gelatines from porcine, bovine, and piscine sources. Chicken skin gelatine formed stable foams by a foaming stability of 83.3% as well as high emulsion activity of 72.8 m2 g−1 compared to commercial gelatines. On the other hand, gel strength and viscosity of chicken skin gelatine were 307 g and 2.5 cP, respectively, and significantly lower than that of commercial gelatines due to high content of impurities. The results concluded that chicken skin may be used in gelatine manufacturing upon efficient removal of fat, which was the most abundant component in the dry matter of chicken skin.
Abstract
Cultured buttermilk is a dairy beverage with a high nutritive value. In the current study, functional cultured buttermilk was formulated using probiotic Lactobacillus plantarum and flaxseed fortification to improve the potential health benefits. The cultured buttermilk samples were analysed for pH, lactic acidity, colour, phase separation, viscosity, microbiology and sensory properties. The results showed non-significant changes in acidity and pH. However, flaxseed fortification decreased phase separation and increased viscosity of buttermilks. In addition, a significant difference in colour attributes was revealed between samples. Sensory characteristics of cultured buttermilks were acceptable to produce a functional food.
Egy köles tájfajta műtrágya-reakciójának vizsgálata
Examination of the reaction to fertilization of regional millet variety
Kutatómunkák általános célja olyan kísérletek végzése, amelyek feltárják az adott régióban perspektivikusan termeszthető fajták, illetve tájfajták optimális műtrágyázási igényeit. Tanulmányunkban a Karcagon nemesített és fenntartott ’Maxi’ köles tájfajta tápanyagreakciójának vizsgálatából származó eredményeinket mutatjuk be a módosított Országos Műtrágyázási Tartamkísérlet (OMTK) 2017. évi és az annak figyelembevételével 2021-ben beállított Műtrágyázási Kísérleti Kert (MKK) adatai alapján. A kísérleteket Karcagon, a MATE Karcagi Kutatóintézetben, egy mélyben szolonyeces réti csernozjom talajon állítottuk be. 2017-ben a módosított OMTK kezelései 4 nitrogén (40, 80, 120, 160 kg ha– 1), 4 foszfor (0, 40, 80, 100 kg ha– 1) és 3 kálium (0, 60, 90 kg ha– 1) dózis kombinációjából adódtak, illetve volt egy műtrágyázás nélküli abszolút kontroll. 2021-ben az MKK kezelései 3 nitrogén (40, 80, 120 kg ha– 1), 3 foszfor (0, 40, 80 kg ha– 1) és 2 kálium (0, 60 kg ha– 1) dózis kombinációját foglalták magukba, illetve mindegyik parcella felére növénykondicionáló szert juttatunk ki. A termesztett növény mindkét évben a karcagi nemesítésű ’Maxi’ kölesfajta volt. A különböző kezeléscsoportok termésre gyakorolt hatásának statisztikai értékelését egytényezős varianciaanalízissel végeztük el. Mindkét vizsgálati évben a 80 kg ha– 1 hatóanyag mennyiségben kijuttatott nitrogén műtrágyázás bizonyult a leginkább megfelelőnek. A magas foszfor dózisok a legtöbb esetben termésdepresszióhoz vezettek. Eredményeink alapján még a közepes – jó kálium ellátottságú karcagi talajokon is hasznos lehet a kálium kijuttatása, bár a káliumtrágyázás termésre gyakorolt hatását a varianciaanalízis nem igazolta. Az Algomel PUSH szerrel végzett növénykondicionálás statisztikailag is igazolhatóan, mintegy 10%-kal növelte a termés nagyságát. Kutatómunkánk folytatásával pontosabban meghatározható lesz számos tájfajta tápanyagreakciója és fajtaspecifikus, a helyi agroökológiai viszonyokat is figyelembe vevő tápanyag dózisok és kombinációk ajánlhatók a gazdálkodóknak.
The general objective of our research is to carry out experiments that are suitable to reveal the optimal fertilization demand of regionally bred or potentially producible crop varieties for a specific region. In our recent study, the results gained from the examination of the nutrient reaction of the regional millet variety ‘Maxi’ bred and maintained in Karcag are introduced based on the data originating from the modified Long-term National Fertilization Experiments (OMTK) in 2017 and from the Fertilization Experimental Garden (MKK) established at Karcag in 2021. Both experiments were set up in the MATE Research Institute of Karcag on a meadow chernozem soil salty in the deeper layers. In 2017, there were 4 nitrogen (40, 80, 120, 160 kg ha−1), 4 phosphorus (0, 40, 80, 100 kg ha−1), and 3 potassium (0, 60, 90 kg ha−1) dosage combinations applied and one unfertilized absolute control in the OMTK trial. In 2021, in the MKK experiment, treatments involved 3 nitrogen (40, 80, 120 kg ha−1), 3 phosphorus (0, 40, 80 kg ha−1), and 2 potassium (0, 60 kg ha−1) dosage combinations, furthermore, on half of the plots a plant conditioner was sprayed. Millet variety ‘Maxi’ bred at Karcag was the indicator crop in both years. For the statistical analysis of the effect of the various treatment groups on yields, One-way ANOVA tests were used. We considered the 80 kg ha−1 nitrogen substance dose the most suitable in both years. High dosage of phosphorus application resulted in yield depression in most of the cases. Based on our results, potassium fertilization can be effective even on the soils of Karcag with medium to good potassium supplies, though the analysis of variance did not justify the effect of K-fertilization on yields. The 10% yields increase due to plant conditioning with Algomel PUSH was statistically proven. By continuing or research, the reaction to fertilization of several regional crop varieties can be determined more precisely, and variety-specific nutrient doses and combinations can be determined and suggested to the local famers taking the regional agri-ecological conditions into consideration.
Abstract
Effect of adding foxtail millet flour (FMF) (10, 20, and 30% w/w) to refined wheat flour (RWF) on physicochemical and rheological properties of dough was studied. Qualitative properties of Brotchen bread including moisture, ash, crude fibre, specific volume, and colour of the breads were evaluated. Adding FMF to the flour increased crude fibre, fat, ash, and protein contents and reduced falling number, damaged starch and wet gluten contents, and sample lightness. Consistograph test indicated that addition of the FMF decreased water absorption capacity, maximum pressure, and tolerance, however, drops in pressure at 250 and 450 s became greater. Alveograph test revealed that with adding FMF, dough resistance to extension and dough strength decreased but an increase in dough extensibility was obtained at FMF30%. Increasing the amount of FMF resulted in a decrease in the volume of the bread, and the FMB (foxtail millet bread) 30% had the highest browning index and b*. The FMB20% had the highest resilience and springiness, while higher level of foxtail (30%) increased chewiness.
Abstract
The aim of the study was to determine whether the physicochemical factors of the matrix and the traditional acid-set cheese-making conditions allow the growth of coagulase-positive staphylococci (CoPS) and the synthesis of enterotoxins, which should contribute to an objective risk assessment in cheese production related to CoPS. CoPS were isolated from 72% of acid-set cheeses ranging from 1.70 to 5.15 log10 CFU g−1. CoPS in a number ≥ 4 log10 CFU g−1 were determined in 5.56% of the acid-set cheese samples. Out of the total number of CoPS isolated from cheese, 37.62% of the isolates have been shown to produce enterotoxins. All isolated strains that produced enterotoxins were identified as Staphylococcus aureus based on the detection of spa gene by PCR. For cheese-derived isolates with CoPS number ≥ 4 log10 CFU g−1, it has been proven that they possess sec gene encoding staphylococcal enterotoxin C. According to our results, during the proper fermentation process of artisanal acid-set cheese, the conditions do not support the growth of a critical level of staphylococci or the production of enterotoxins.
Abstract
Its ability to survive under different environmental conditions makes Listeria monocytogenes a critical concern for food safety. When the microorganisms are exposed to sublethal heat treatment above their optimum growth temperature, they increase stress adaptation for further heat treatments. In order to investigate heat stress resistance of L. monocytogenes, L. innocua as a surrogate was exposed to sublethal heat at 46 °C for 30 and 60 min, prior to heat treatment at 60 °C. There was no significant difference in D60°C values between samples exposed to sublethal heat for 30 min and non-pre-heat-treated samples (control) (P > 0.05). In comparison, sublethal heat treatment for 60 min caused a significant increase in D60°C values compared to control samples (P < 0.05). Additionally, cluster analysis of mass spectra obtained from MALDI-TOF was analysed by discriminant analysis of principal components (DAPC) for sublethal heat treatment at 46 °C for 30 min and control group to check stress response at the proteomic level. However, differentiation of stress responses by distinct clusters was not revealing.
Abstract
Gluten-free (GF) breads are often described with low quality, rapidly staling, dry mouthfeel and crumbling texture attributes. In lack of recent texture profile data on commercially available, preservative-free, freshly-baked GF bread, this study aimed to compare different types of GF products with their wheat-based counterparts during a 4-day-long storage test. Texture analysis data showed that GF loaves performed better than or comparable to the wheat-based ones in hardness, springiness and cohesiveness. Among sensorial properties mouth-feel, softness and aroma were evaluated as significantly better or similar for GF versus wheat-based products. GF cob had a saltier taste, which reduced the flavour experience. Both the texture results of the storage test and sensory data showed that the quality of GF bread products improved in recent years; they stayed comparable with their wheat-based counterparts even during a 4-day-long storage period.
Abstract
Fresh thyme leaves (Thymus vulgaris L.) were dried at 45 °C for 5 h and naturally fermented at 20 °C in a brine solution containing salt and vinegar for 18 days. The ethanolic extracts of fresh (FT), dried (DT), and fermented-pickled (PT) thyme leaves were assessed in terms of total phenolic content (TPC), total flavonoid content (TFC), antioxidant capacity values and subjected to in vitro gastrointestinal digestion. TPC, TFC, and antioxidant capacity values of fermented thyme leaves were found significantly higher than of dried and fresh samples. The bioaccessibility index (BI) value for TPC and TFC was highest for PT and lowest for DT, indicating that both processes had different effects on the structure of phenolic compounds present in the thyme leaves. Similarly both Recovery and BI values of DPPH antioxidant capacity were highest for PT, but lowest for fresh samples. When CUPRAC assay was applied, the recovery % for FT and PT was similar, and the BI was higher for FT. Results showed that compared to the results of fresh thyme leaves, drying and pickling had a considerable effect on the initial phenolic compounds extracted and their fate during in vitro digestion.
Abstract
This work aimed to evaluate the effect of ethylene treatment on ripening of 1-MCP treated pear after 6 months of cold storage. Pear treated with gaseous 1-MCP at 625–650 ppb for 24 h at 0 °C was stored at 0 °C for 6 months with normal air, and treated groups were exposed to 100 ppm ethylene at 20 °C for 24 h. After that, samples were kept at 0, 10, and 15 °C for 2 weeks. Stiffness, chlorophyll fluorescence, ethylene and CO2 production of fruit were investigated during 2 weeks. Application of ethylene resumed the ripening of pear after long term storage. The results showed that fruit treated with ethylene achieved more homogeneous surface colour in comparison with non ethylene treated pears. In addition, the ethylene and carbon dioxide production of ethylene treated pears had higher values than that of control. The ethylene treatment could accelerate the softening of pear. Temperature also has significant effect on ripening during storage. This study found that ethylene treatment could accelerate the normal ripening of 1-MCP treated pears.
