EFFECT OF LIPASE ENZYME ON THE RIPENING OF WHITE PICKLED CHEESE

The effect of addition of pregastric lipase enzyme on the accelerated ripening of white pickled cheese was investigated. Commercial pregastric lipase was added to milk before rennet addition at a level of 0,5, 8, 11 g per 100 L of milk and cheeses were made from this milk. Total solids, fat, total nitrogen, salt, titratable acidity, pH and free fatty acids (C₂-C_18:1) were analysed in the samples during 1–90 days of ripening period at 15 days intervals. Total solids, fat, total nitrogen, salt, titratable acidity, and pH of cheeses slightly increased during the ripening period. Free fatty acids and volatile free fatty acid contents in cheeses made from pregastric lipase added milk were affected by pregastric lipase and their contents were increased significantly (P<0.01) during the ripening period. Particularly, when cheese had a high level (11 g per 100 L milk) pregastric lipase, the amounts of butyric, caproic and caprylic acids in white pickled cheese were quite high. The relative amounts of volatile free fatty acids varied with storage time and pregastric lipase levels.     

INHIBITION OF STAPHYLOCOCCUS AUREUS IN BUFFER, CULTURE MEDIA AND FOODS BY LACIDIN A, A BACTERIOCIN PRODUCED BY LACTOBACILLUS ACIDOPHILUS OSU133

Thirty seven strains of lactobacilli and leuconostocs were screened for bacteriocin production. A bacteriocin-like substance (designated lacidin A) was detected in culture filtrate of Lactobacillus acidophilus OSU133. Lacidin A inhibited Enterococcus faecalis, L. acidophilus, Lactobacillus delbrueckii subsp. lactis, and Staphylococcus aureus. The bacteriocinogenic nature of lacidin A was confirmed by eliminating the inhibitory effects of acid, hydrogen peroxide and phage and by loss of activity upon hydrolysis with proteolytic enzymes. The bacteriocin is relatively heat-stable and has considerable bactericidal action against S. aureus in phosphate buffer. Lacidin A also demonstrated bacteriostatic action against S. aureus in brain heart infusion and heat-treated milk and liquid whole egg.     

EFFECT OF CALCIUM AND PHOSPHORUS, RESIDUAL LACTOSE AND SALT-TO-MOISTURE RATIO ON TEXTURAL PROPERTIES OF CHEDDAR CHEESE DURING RIPENING

The texture profile analysis (TPA) parameters and meltability of Cheddar cheeses with varying levels of calcium (Ca) and phosphorus (P) content, residual lactose content and salt‐to‐moisture (S/M) ratio were studied at 0, 1, 2, 4, 6 and 8 months of ripening. The TPA hardness had an inverse relationship with the meltability of Cheddar cheese and at any given ripening time, lower TPA hardness corresponded to higher meltability of Cheddar cheese. Higher Ca and P content (0.67% Ca and 0.53% P) in Cheddar cheese resulted in up to 22.8, 5.7, 14.6, 13.5 and 35.2% increase in hardness, springiness, cohesiveness, resilience and chewiness values, respectively, and up to 23.5 and 27.7% decrease in meltability and adhesiveness values during ripening compared to the Cheddar cheese prepared with lower Ca and P content (0.53% Ca and 0.39% P). Higher residual lactose content (1.4%) in Cheddar cheese resulted in up to 24.6, 8.8 and 20.0% increase in hardness, cohesiveness and chewiness values, respectively, and up to 12.7% decrease in meltability value in the Cheddar cheese during ripening compared to the lower lactose content (0.78%). High S/M ratio (6.4) resulted in up to 29.4, 30.3 and 29.4% increase in hardness, adhesiveness and chewiness values, respectively, and up to 7.3% decrease in meltability value in Cheddar cheese compared to low S/M ratio (4.8) during ripening.     

EFFECT OF RIPENING AND TYPE OF RENNET ON THE MINERAL CONTENT OF LOS PEDROCHES CHEESE

The changes in the macro and micromineral contents (Ca, P, Na, K, Mg, Fe, and Zn) of Los Pedroches cheese, manufactured with pure ewe's milk, were investigated during 100 days' ripening. The effect of the rennet type used (animal or vegetable) on these minerals was investigated too. Using these mineral values, expressed as a function of the dry matter, an analysis of covariance was applied. The rennet type had an influence on the P and Zn contents of the cheeses. There was a significant decreasing trend in the levels of P, Zn and Na values during ripening.     

CHANGES IN VISCOELASTIC PROPERTIES DURING THE RIPENING OF ARZÚA-ULLOA CHEESE. EFFECT OF PROTEOLYSIS

Changes in viscoelastic properties during the ripening of three different batches of Arzúa-Ulloa cheese, a traditional Spanish variety, were studied. Proteolysis changes were determined in terms of the typical nitrogen fractions, these fractions were significantly correlated with the measured viscoelastic properties. Substantial changes in stress amplitude over the linear viscoelastic range were observed at 20C, as were significant differences in storage modulus (G') and viscous modulus (G") throughout the ripening period. Both moduli decreased markedly over the first two weeks, but exhibited an opposite trend from the third week. Mechanical spectra were recorded at 20, 25, 30 and 35C throughout the ripening period. The viscous component significantly increased compared to the elastic one as function of temperature and ripening time.     

EFFECT OF OIL CONTENT ON THE LOSS OF ALPHA-ACID FROM HOPS DURING STORAGE

Examination of a wide range of hop varieties showed that the percentage loss of α-acid in storage was related to the essential oil content of the samples. Seedless hops, having higher oil contents, lost more α-acid than seeded hops of the same variety. The variety Bullion grown for isomerized extract manufacture should be picked 7–10 days earlier than normal to minimize loss of α-acid before processing.     

银耳多糖对嗜酸乳杆菌L101发酵生长影响的研究

研究嗜酸乳杆菌在发酵过程中银耳多糖对其菌体细胞增殖作用的影响。研究以银耳（Tremella fuciformis）为原料,采用热水抽提和DEAE—sepharoseFF色谱分离技术获得银耳多糖以及银耳多糖两组分-酸性多糖和中性多糖;将分离的多糖按不同比例添加于MRS培养基中,以评价菌体各组分对嗜酸乳杆菌细胞增殖的作用。结果表明：银耳多糖添加量为3g／L～7g／L可有效促进嗜酸乳杆菌L101增殖,其最佳添加量为5g／L,在此添加量下,菌体发酵16h后,活菌数可达8．13&#215;10^8cfu／mL;而≥9s／L添加量会抑制菌体的增殖。研究同时证实,酸性多糖是银耳多糖中促进嗜酸乳杆菌L101生长的主要有效成分,5虮的酸性多糖添加量,发酵16h后,活菌数可达1．01&#215;10^9cfu／mL,较5g/L精制银耳多糖组,生物量提高了24．2％。     

EFFECT OF DIRECT APPLICATIONS OF SAGE (SALVIA OFFICINALIS L.) LEAVES ON OXIDATIVE STABILITY OF SUNFLOWER OIL DURING ACCELERATED STORAGE

In this study, various sage applications were examined on oxidative stability of sunflower oil during accelerated storage. There are three applications: (1) direct sage leaves (S); (2) deodorized sage leaves (DeS); and (3) essential oil of sage leaves. The main compounds of essential oil were identified as α -thujone (35.87%), β -thujone (14.41%), 1,8-cineol (10.59%) and camphor (10.09%). Oxidative stability of these three applications was tested by Schall Oven test at 60C applying peroxide value and conjugated dienes, and Rancimat at 110C. Whereas the highest antioxidants activity was found for 2% S followed by 0.5% S and 2% DeS, all sage treatments statistically retarded the oxidation compared with the control sample. The most appealing result was that the residue can be used as a natural antioxidants. That means the reuse of residue may decrease economic losses and health risk in comparison with synthetic antioxidants and extracts because it is completely natural and contains no residual solvent.

PRACTICAL APPLICATIONS

While almost all of previous studies were concentrated on the use of herb extracts, our study investigates the results of direct application of sage on oxidation. Especially with this study, we have evaluated a possible application area for sage residue leftover after the deodorization process.     

EFFECT OF STORAGE PERIOD AND EXPOSURE CONDITIONS ON THE QUALITY OF BOSANA EXTRA-VIRGIN OLIVE OIL

Changes in quality parameters, antioxidant compounds, oxidative stability and antioxidant activity during 18 months of storage of a monovarietal extra‐virgin olive oil from Bosana cultivar , and exposed to light and dark, were studied. Analysis of data showed that all the parameters underwent significant changes during storage: free acidity, peroxide and ultraviolet (UV) spectrophotometric indexes remained below the limits reported in the EEC Regulations 2568/91 and 1989/03 , and these are: ≤0.8% for acidity, ≤20 meq O₂/kg for peroxide and ≤2.50 and ≤0.22 for K232 and K270, respectively. Phenol andα‐tocopherol content decreased during storage (42.0 and 29.6%, respectively) while chlorophylls and carotenoids underwent a decrease until 8 months of storage (49% and 30%, respectively); after that, the values remained constant. Oxidative stability and antioxidant activity had not changed dramatically during 18 months. Phenols were significantly correlated to the antioxidant activity of the oil, while oxidative stability measured by Rancimat did not show any correlation with carotenoids, chlorophylls, phenols andα‐tocopherol. Regarding exposure conditions, storage in the dark was better in retaining the quality of the oil, as expected.     

INHIBITION OF LISTERIA MONOCYTOGENES AND OTHER BACTERIA BY A PLANT ESSENTIAL OIL (DMC) IN SPANISH SOFT CHEESE

The inhibitory effects of a mixture of plant essential oils (DMC) were tested in culture media and Spanish soft cheese. The minimum inhibitory concentration (MIC) was determined in plate count agar and tryptose broth, with pH adjusted to 6.5, against Listeria monocytogenes, Listeria innocua, Staphylococcus aureus, Lactobacillus brevis, Micrococcus luteus, Salmonella cholerasuis, Escherichia coli O157:H7 , Enterobacter cloacae, Pseudomonas aeruginosa and Pseudomonas fluorescens. The mixture of essential oils inhibited all Gram-positive bacteria tested at 40 ppm, but higher concentrations were needed to inhibit Gram-negative bacteria, and no inhibitory effect was found against Ps. fluorescens. The effects of DMC against L. monocytogenes and E. coli O157:H7 were evaluated in Spanish soft cheese (Queso Fresco, pH=6.5) stored at 7C. DMC had a bacteriostatic effect against L. monocytogenes at concentrations of 2500 ppm but was ineffective to control the growth of E. coli O157:H7 .     

EFFECT OF STORAGE AND DACUS INFECTION OF OLIVE FRUITS ON THE QUALITY OF THE PRODUCED VIRGIN OLIVE OIL

Olives from three different locations ( Olea europaea cv. Koroneiki), uninfected or infected by the insect Dacus oleae, were collected and stored at 15°2C for 21 days. Samples were taken at 0, 3, 7, 10, 12, 14, 17 and 21 days following collection. Moisture and oil content of olive fruits and the quality parameters of the extracted virgin olive oil were evaluated. Analytical parameters determined were titratable acidity, peroxide value and the specific extinction coefficients at 232 nm (K₂₃₂ and 270 nm (K₂₇₀). Regression equations and best fitting curves between examined parameters and time were evaluated. Olive oil from fly infected olives had higher initial values and a higher rate of increase of the parameters measured. The only parameter affecting oil quality was K₂₇₀. Maximum storage time within legal limit for K₂₇₀ was 16 days for fly uninfected and 10 days for fly infected olives.     

CHEMICAL COMPOSITION AND ANTIMICROBIAL PROPERTIES OF THE ESSENTIAL OIL OF ORIGANUM SACCATUM L.

The chemical constituents of essential oil isolated by hydrodistillation of aerial parts of Origanum saccatum L. growing wild of 39 constituents were identified accounting for 99.11% of the oil of O. saccatum. The oil of O. saccatum contained, as main components, p -cymene (82.8%), γ-terpinene (6.2%), p -cymene-8-ol (1.5%) and carvacrol (1.2%). The essential oil of O. saccatum was characterized by its high content of p -cymene.
Preliminary experiment was carried out in vitro using the diffusion method to investigate antimicrobial activity of the O. saccatum oil. The oil exerted varying levels of antimicrobial effects on the growth of all microorganisms (except for 100 ppm which belongs to Bacillus subtilis, Bacillus aureus ). The antimicrobial activity of the O. saccatum oil was established by using agar diffusion method. The results showed that antimicrobial activity increased depending on the concentration degree used. The highest sensitive bacteria had Staphylococcus aureus and Escherichia coli. As a result, inhibitory effect of oil was weak on tested bacteria compared with fungi. The extent of inhibition of tested microorganism growth was dependent on the concentrations of essential oil used.

PRACTICAL APPLICATIONS

Some investigations showed that the use of spices in place of chemicals and synthetics has become indispensable because of their antimicrobial effects and also because of the increasing risk of the side effects of chemical and synthetic preservatives on health. Also, spices and derivatives have been used since ancient times to preserve foods, make foods tastier, cure diseases and produce aromatic substances. Many species of aromatic plants belonging to the Labiatae family grow wild in the east Mediterranean basin. Dried oregano leaves are well known not only in the herb industry mainly but also for other appetizing applications, and as a source of essential oils     

EFFECT OF SOLAR DRYING ON THE COMPOSITION OF ESSENTIAL OIL OF SACHA CULANTRO (ERYNGIUM FOETIDUM L.) GROWN IN THE PERUVIAN AMAZON

Two solar drying methods (direct cabinet solar dryer and indirect cabinet solar dryer) were tested under tropical conditions for drying aerial parts of sacha culantro ( Eryngium foetidum L.) in Pucallpa City (Peruvian Amazon). The drying behavior was monitored during all experimental runs. Dried samples and fresh leaves were hydrodistilled and isolated oils were analyzed using gas chromatography with flame ionization detector and gas chromatography-mass spectrometry. ( E )-2-dodecenal was determined as the main constituent of the sacha culantro essential oil, averaging 61.8–62.2%, followed by n -dodecanal (10.9–15.5%), ( E )-2-tetradecenal (6.7–7.6%) and 1-tetradecene (3.6–5.7%). When comparing both solar drying methods, the indirect method was found as more suitable for drying E. foetidum since the dried product resembled the fresh herb more closely in its chemicalcomposition and had better appearance. However, a better drying efficiency of 10.3% was achieved when drying in the direct solar dryer compared with 5.8% for the indirect solar dryer.

PRACTICAL APPLICATIONS

Harvested leaves of sacha culantro are widely used as a condiment in a range of Peruvian, Latin American and Caribbean foods, including vegetable and meat dishes, canned food and sauces. There is lack of any postharvest processing of this herb although it may extend possibilities for use of the herb and facilitate the product export from local production areas and might be a good economic source for poor local farmers. This study shows solar drying as a reasonable preservation technique of sacha culantro leaves which may have a practical application in case of postharvest processing of the herb in the target region of Pucallpa City in Peruvian Amazon.