scholarly journals The Effect of Lipolytic Enzymes of Bacillus spp. on Quality of Ultra-High-Temperature-Treated Milk

2006 ◽  
Vol 75 (3) ◽  
pp. 427-435 ◽  
Author(s):  
B. Janštová ◽  
L. Vorlová ◽  
M. Dračková
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Storage Temperature ◽  
Lipolytic Activity ◽  
Storage Period ◽  
Raw Milk ◽  
Model Case ◽  
Number Of Microorganisms ◽  
Bacillus Spp ◽  
Initial Content

Lipolysis was monitored based on determining the concentration of free fatty acids in milk, on the model case of UHT milk contamination with spores of 15 B. licheniformis, B. subtilis and B. cereus strains isolated from farm environment and raw milk. Lipolysis was not recorded at storage temperature of 4 °C, whereas significant changes in levels of free fatty acids were shown at storage temperature of 24 °C. After 3 weeks of storage the initial content of 41.97 mmol·kg-1 of fat rose to as much as 1,617.22 mmol·kg-1 of fat. The extent of the change depended mainly on the Bacillus spp. species and the storage period and, to a certain degree, also on the initial number of microorganisms. Significant lipolytic activity was detected in association with B. licheniformis and B. cereus species. It was found that spores of resistant B. licheniformis strains may survive 100 °C/10 min and 135 °C/5 s heating and show lipolytic activity.

scholarly journals Effects of lipolytic enzymes Pseudomonas fluorescens on liberation of fatty acids from milk fat

2000 ◽  
Vol 18 (No. 5) ◽  
pp. 175-182 ◽  
Author(s):  
M. Vyletělová ◽  
J. Ficnar ◽  
O. Hanuš
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Pseudomonas Fluorescens ◽  
Milk Fat ◽  
Storage Temperature ◽  
Raw Milk ◽  
Lipolytic Enzymes ◽  
Pasteurized Milk ◽  
Milk Samples

Effects of thermostable lipolytic enzymes Pseudomonas fluorescens 66 ZB in pasteurized milk on concentration of free fatty acids (VMK) in milk were studied in selected milk samples. Identical bulk milk samples were analysed by the method specified in previous papers (Vyletělová et al. 1999a, b, 2000). Reference milk samples (without bacterial strains) and the experimental ones (containing Ps. fl. 150 th. CFU/ml and 2800 th. CFU/ml, resp.) were stored at 6.5°C and 14°C and analysed at regular time intervals (24 h) – Table 1. An extractive-titric method (Kadlec et al. 1996; Table 2 and Fig. 2) was used for monitoring of fatty acid (MK) liberation. Precise analyses of MK and VMK were made by the chromatographic method (Figs. 1, 3 and 4). Medium-chain fatty acids (C12–C16) are liberated first of all; short-chain acids (C6–C10) were found sporadically or in very small quantities (Table 2). Dissociation constant of the specific fatty acid liberated from milk fat affects principally relationships between pH and free fatty acid concentration. The predominating proportion of long-chain acids in liberated fatty acid formation is associated with lower reduction of pH as compared to the predomination of fatty acids with shorter chains associated with more substantial reduction of pH. In our study, a rapid decrease of pH was noted before 168 h (Table 24); this corresponds to low concentrations of short-chain free fatty acids. Vyletělová et al. (2000) found significant relations between pH and contents of VMK (measured by the extractive-titric method); in some samples, correlation coefficients amounted to r = –0.93*** (P £ 0.001). The extractive-titric method analysing VMK concentrations (mmol/kg milk fat) provides results characterized by a systematic rise (e.g., 32.0 mmol/kg instead of 13.0 mmol/kg in raw milk). According to Kratochvíl (1992) 20 mmol VMK/kg milk fat signalized the starting point characterizing flavour degradation of milk caused by activities of fatty acids C12–C14 above all; the transformed value (respecting specifics of the extractive-titric method) amounts to 49 mmol/kg. In case of higher storage temperature a significant break is found after 144 h; in case of lower temperature this break is after 192 h (Table 2). Limits determining potential lipolytic modifications of milk flavour (RLZCHV) as related to specific samples and temperatures at VMK levels amounting to 49 mmol/kg or 20 mmol/kg are outlined in Fig. 2. Milk samples No. 5 and No. 6 stored at higher temperature surpassed this risk limit at 56 h and 64 h, respectively (Table 2, Fig. 2). On the contrary, milk samples stored temperatures corresponding to the standard storage temperature (storage of raw milk, transport, storage of pasteurized milk) surpass the mentioned risk level after 90 h and 140.5 h. Obtained results document the predominant role of storage temperature in the whole complex (production and processing of milk as a raw material or an intermediate product); evident differences in contamination rates (105 an 106) can be characterized as secondary effects in this case (Table 2). As related to practical conditions, the mentioned facts imply immediate processing of raw milk and pasteurized milk. This postulate must be respected namely by dairy plants producing delicate milk products. Vyletělová et al. (2000) found a notable VMK increase/24 h (7–11 mmol/kg milk fat) under specific temperatures and microbial contamination.

Source of plasma free fatty acids in dogs receiving fat emulsion and heparin

1963 ◽  
Vol 204 (4) ◽  
pp. 691-695 ◽  
Author(s):  
H. C. Meng ◽  
B. Edgren
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Lipolytic Activity ◽  
Blocking Agent ◽  
Fat Emulsion ◽  
Similar Reduction ◽  
Plasma Free Fatty Acids ◽  
Fat Infusion ◽  
Plasma Ffa ◽  
Slight Rise

Unanesthetized dogs were given either 3.0 g fat/kg as a 20% fat emulsion or heparin (2 mg/kg) intravenously or both. Plasma free fatty acids (FFA) and lipolytic activity were determined at intervals. In some experiments hexamethonium (5 mg/kg), a sympathetic ganglionic blocking agent, was administered intravenously either before or after fat or heparin. In fasting dogs fat infusion produced a moderate and heparin caused a slight rise in plasma FFA. Heparin given during lipemia produced a marked elevation of plasma FFA. The plasma lipolytic activity was increased after fat emulsion or heparin. Hexamethonium reduced the fasting plasma FFA about 70% or 0.40–0.6 mEq/liter. A similar reduction of plasma FFA also was observed when hexamethonium was administered during fat infusion or after heparin. Hexamethonium did not affect the increase in plasma lipolytic activity following the administration of fat emulsion or heparin. It seems probable that the increase in plasma FFA observed after intravenous infusion of fat emulsion or heparin is mainly due to the result of intravascular lipolysis.

scholarly journals Spoilage potential of spore-forming bacteria from refrigerated raw milk

2018 ◽  
Vol 39 (5) ◽  
pp. 2049 ◽  
Author(s):  
José Carlos Ribeiro Júnior ◽  
Ronaldo Tamanini ◽  
André Luís Martinez de Oliveira ◽  
Juliane Ribeiro ◽  
Vanerli Beloti
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Shelf Life ◽  
Lipolytic Activity ◽  
Raw Milk ◽  
Rrna Gene ◽  
16S Rrna Gene Analysis ◽  
Pasteurized Milk ◽  
Bacillus Spp ◽  
Aerobic Spores

Aerobic bacterial spores are an important group of microorganisms in raw milk. These microbes are thermoduric, whereas the vegetative forms are thermophilic, thermoduric and psychrotrophic and reduce the shelf life of pasteurized milk. In Brazil, there are a lack of studies on the load of aerobic spores in raw milk; thus, little is known about the spoilage activity of these organisms. The aim the present study was to quantify the aerobic spores in Brazilian refrigerated raw milk of dairy region of Castro, Paraná state, assess the potential proteolytic and/or lipolytic isolates and identify the microorganisms derived from the germination. Twenty milk samples were evaluated, and the aerobic spore count was performed after plating the samples following heat treatment at 80°C for 12 min. The activity proteolytic and lipolytic isolates were evaluated through subculture on milk agar and tributyrin agar, respectively, and these microorganisms were identified using partial 16S rRNA gene sequences that were compared through GenBank. The aerobic spore counts ranged from 1 to 3.7 log CFU.mL-1, with a mean of 1.75 (± 0.59) log CFU.mL-1. After spore germination, 137 aerobic bacterial isolates were obtained, 40 of which (29.2%) showed milk spoilage activity. Among these, 31 isolates (77.5%) were proteolytic and lipolytic, seven isolates (17.5%) were exclusively lipolytic and two isolates (5%) were only proteolytic. Based on the 16S rRNA gene analysis, Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) and Brevibacillus spp. (2.5%) were identified. Studies of Brazilian raw milk microbiota have not yet described B. circulans which are frequently detected in milk from other countries. Among the 22 B. licheniformis isolates, 21 microbes (95.5%) showed proteolytic and lipolytic activity, and one isolate (4.5%) exhibited only proteolytic activity. The two B. pumilus isolates were proteolytic and lipolytic, whereas the B. circulans isolate was only lipolytic. Among the 11 Bacillus spp. isolates, eight isolates (72.7%) were proteolytic and lipolytic, one isolate (9.1%) was proteolytic and the other two isolates (18.2%) were lipolytic. The three Paenibacillus spp. and Brevibacillus spp. isolates were primarily lipolytic. Therefore, to extend the shelf life of pasteurized milk, preventive measures must be adopted to reduce contamination with spores because one-third of these microorganisms exhibited proteolytic and/or lipolytic activity.

Chemical Alterations in Fish Tissue During Storage at Low Temperatures

1969 ◽  
Vol 52 (5) ◽  
pp. 904-910 ◽  
Author(s):  
Garnett Wood ◽  
Lane Hintz ◽  
Harold Salwin
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Low Temperatures ◽  
Unsaturated Fatty Acids ◽  
Storage Temperature ◽  
Neutral Lipids ◽  
Fish Tissue ◽  
Protective Mechanism ◽  
Polyunsaturated Acids

Abstract Chemical changes that occur in the proteins, nucleotides, and lipids of fish tissue during storage at low temperatures were investigated. Homogenized tissue, prepared from fresh rock-fish (striped hass, Roccus species), was stored up to six days at temperatures from -10° to 4°C and then analyzed. At 0°C and below, the solubility of myofibrillar proteins decreased. There were also changes in polyacrylamide gel electrophoretic patterns of protein extracts. The total nucleotide content decreased rapidly at all temperatures. The lipids were extracted from each sample and separated into neutral lipids, phospholipids, and free fatty acids by column chromatography. The fatty acid composition of each fraction was determined by gas chromatography. In the fresh tissue, polyunsaturated acids occurred in greatest proportion in the free fatty acid and phospholipid fractions, whereas inono-unsaturated acids were inofe highly concentrated in the neutral lipids. The percentages of saturated acids were approximately the same in all fractions. During storage, there were considerably larger losses of individual acids from phospholipids than from neutral lipids. The polyunsaturated acids of the phospholipid fraction were affected most. Over 10% of these aeids were lost in six days at ice temperature, but only a small proportion of the losses was accounted for by increases in free fatty acids. Oxidative proo esses may account for the imbalance because the rate of oxidation, as measured by the thio-barbituric acid test, increased with storage temperature in the same manner as the rale at which unsaturated fatty acids were lost from the pliospliolipuls. Losses of polyunsaturated acids from the neutral lipids were much smaller, suggesting a selectively protective mechanism or environment in that fraction. The changes in the phospholipid fatty acids may provide the basis for useful objective tests of fish lecomposilion.

Changes in free fatty acids during the ripening of Idiazabal cheese: influence of brining time and smoking

1994 ◽  
Vol 61 (2) ◽  
pp. 281-288 ◽  
Author(s):  
Ana I. Nájera ◽  
Luis J. R. Barron ◽  
Yolanda Barcina
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Free Fatty Acids ◽  
Free Fatty Acid Content ◽  
Acid Content ◽  
Lipolytic Activity ◽  
Fatty Acid Content ◽  
Ripening Period ◽  
Cheese Ripening

SummaryThe effect of brining time and smoking on the free fatty acid content of Idiazabal cheese during ripening was examined. The main free fatty acids considered underwent at least some increase during the first stage of ripening before day 90 and tended to level off around a constant value towards the end of the ripening period. There were significant differences in free fatty acid levels during ripening among cheeses with different brining times and between smoked and unsmoked cheeses. Brining time and smoking exerted marked effects on lipolytic activity during cheese ripening, depending upon the free fatty acid involved and ripening time. In general, brining and smoking led to increases in free fatty acid levels at the end of the ripening period; the different behaviour of butyric acid may be due to a specific lipolytic activity.

scholarly journals Variations in fatty acid composition and oxidative stability of hazelnut (Corylus avellana L.) varieties stored by traditional method

2019 ◽  
Vol 70 (1) ◽  
pp. 288 ◽  
Author(s):  
H. Karaosmanoğlu ◽  
N. Ş. Üstün
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Free Fatty Acids ◽  
Acid Composition ◽  
Storage Period ◽  
Peroxide Number ◽  
External Interference

In this study, the changes in fatty acid composition, peroxide number, free fatty acids, oleic acid/ linoleic acid (O/L) and iodine value (IV) were investigated during the traditional storage of hazelnuts. The samples were selected from Giresun Quality Tombul, Kara and Sivri hazelnut varieties with economical prescription. Samples were stored according to the conventional methods in external interference-free warehouses until the next harvest time. At the end of storage, the amount of oleic acid in all varieties increased while the amount of linoleic acid decreased. Even though an increase in the free fatty acids and peroxide number in all types of hazelnuts during storage was determined, the values were considerably lower than the rancidity limits at the end of the storage period. As a result of the study it was observed that the hazelnut shell is an important preservative during storage and that hazelnuts can be preserved until the next harvest period under simple storage conditions.

scholarly journals The effect of cold storage, time and the population of Pseudomonas species on milk lipolysis

2019 ◽  
Vol 70 (2) ◽  
pp. 300
Author(s):  
F. A.B. Pereira ◽  
L. L. Luiz ◽  
S. R. Bruzaroski ◽  
R. C. Poli-Frederico ◽  
R. Fagnani ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Pseudomonas Putida ◽  
Pseudomonas Fluorescens ◽  
Cold Storage ◽  
Storage Time ◽  
Raw Milk ◽  
Lower Index ◽  
Whole Milk

The aim of this study was to evaluate the lipolytic index (LI) of Pseudomonas fluorescens and Pseudomonas putida (2, 5, 6 log CFU/mL) in milk during 96 h by the Lipo R method. The strains were isolated from refrigerated raw milk (30 °C, 48 h), and species were confirmed by PCR, inoculated in reconstituted whole milk, and stored at 2 °C, 4 °C, and 8 °C. The storage time (ST) and temperature were associated with LI of P. putida. The interaction among lipolysis, temperature, and ST occurs even with a low population of P. putida and these variables combined together contributed to about 77% of the free fatty acids (FFA) in milk. The ST, temperature, and population of P. fluorescens showed a significant effect on its LI, and the variables contributed to about 43% of FFA. LI was about 224% higher in milk with P. fluorescens than with P. putida. The reduc-tion in ST and milk temperature resulted in a decrease in lipid lysis and a lower index of FFA by P. putida and P. fluorescens, with P. fluorescens showing a higher lipolytic capacity.

Changes in lipid fractions and sensory properties of Idiazabal cheese induced by lipase addition

2004 ◽  
Vol 71 (3) ◽  
pp. 372-379 ◽  
Author(s):  
Luis JR Barron ◽  
Igor Hernández ◽  
Ainhoa Bilbao ◽  
Cristian E Flanagan ◽  
Ana I Nájera ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Lipolytic Activity ◽  
Sensory Properties ◽  
Short Chain ◽  
Pregastric Lipase ◽  
Lipid Fractions ◽  
Texture Attributes ◽  
Long Chain

This work studied the addition of an adequate lipase to enhance lipolysis reactions and the development of piquant flavour and sharp odour in Idiazabal cheese, as an alternative to the use of lamb rennet paste. Cheeses were manufactured from bulk raw ewes' milk in 50 l vats with commercial bovine rennet and 80 lipase units of pregastric or 180 lipase units of fungal lipase and ripened for 180 days. A higher lipolytic activity was induced by lipase addition promoting strong changes in odour and flavour attributes. Both fungal and pregastric lipases increased the content of total free fatty acids (FFA), but the fungal lipase released mainly medium- and long-chain FFA. In contrast, the pregastric lipase preferably released short-chain FFA. Diglyceride (DG) content was considerably higher in cheeses made with added pregastric lipase compared with those made with fungal lipase or with no lipase. Monoglycerides (MG) were detected only in cheeses made with either lipase added, reaching comparable concentrations after ripening for 180 days. The cheeses made with pregastric lipase had the highest scores for odour and flavour intensity, and sharp and rennet odours, desirable attributes for the Idiazabal cheese made with lamb rennet paste. None of the texture attributes were significantly influenced by the concentrations of MG and DG in the cheeses made with either lipase. Thus, the pregastric lipase was more appropriate than the fungal lipase to develop a more traditionally-flavoured Idiazabal cheese.

A modified ultra high temperature treatment for reducing microbial lipolysis in stored milk

1987 ◽  
Vol 54 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Anthony R. Bucky ◽  
Patrick R. Hayes ◽  
David S. Robinson
Keyword(s):  
Heat Treatment ◽  
Fatty Acids ◽  
High Temperature ◽  
Free Fatty Acids ◽  
Storage Period ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Viable Cells ◽  
Whole Milk ◽  
Ultra High Temperature

SummaryCultures ofPseudomonasP46 grown in whole milk to contain ∼ 2 × 107or 1 × 108viable cells ml−1before ultra high temperature (UHT) treatment (140°C for 5 s) demonstrated near linear increases in the concentration of short-chain free fatty acids (FFA) during storage at 20°C. However with 5 × 106cells ml−1before UHT heat treatment there was no detectable increase in these FFA levels over a 6-month storage period. A novel heat treatment (140°C for 5 s followed by 60°C for 5 min) reduced the rate of production of volatile FFA to < 10% of the rates achieved after the normal UHT treatment.

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