Free fatty acids and oxidative changes of a raw goat milk cheese through maturation

Free fatty acids (FFA) and lipid and protein oxidation changes were studied throughout maturation process of a raw goat milk cheese with protected designation of origin. Cheeses were analyzed at 4 different times of maturation, at 1, 30, 60, and 90 d. All FFA significantly increased during maturation and the relative increase was higher for long-chain than medium- or short-chain FFA. At the end of maturation, oleic (C18:1 n9), butyric (C4:0), and palmitic (C16:0) acids were the most abundant. The higher levels of short-chain fatty acids (SCFA) regarding total FFA obtained at the end of Ibores cheese ripening compared with other raw goat milk cheeses, highlight the notable role of SCFA on the flavor of this cheese owing to their low-odor thresholds. Lipid oxidation values significantly increased during maturation process but low levels of malondialdehyde were reported; however, protein oxidation did not significantly change during ripening.     

Dietary fiber from coconut flour: A functional food

To determine the effectiveness of dietary fiber present in coconut flour as a functional food, the following studies were conducted: (a) Dietary Fiber Composition and Fermentability of Coconut Flour; (b) The Effect of Coconut Flour on Mineral Availability from Coconut Flour Supplemented Foods; (c) Glycemic Index of Coconut Flour Supplemented Foods in Normal and Diabetic Subjects; and (d) The Cholesterol Lowering Effect of Coconut Flakes in Moderately Raised Cholesterol Levels of Humans. The dietary fiber content of coconut flour was 60.0 ± 1.0 g/100 g sample, 56% insoluble and 4% soluble. Fermentation of coconut flour produced short chain fatty acids with butyrate (1.73 ± 0.07 mmol/g fiber isolate) > acetate (1.40 ± 0.12; (P < 0.05) > propionate (0.47 ± 0.01; P < 0.05). Iron and zinc availability were highest for carrot cake (Fe, 33.3 ± 0.7%; Zn, 12.6 ± 0.1%) supplemented with 20% coconut flour while multigrain loaf supplemented with 10% and macaroons with 25% coconut flour were highest for calcium availability (63.4 ± 8.0% and 38.7 ± 1.1%, respectively). Increasing concentrations of dietary fiber from coconut flour did not affect mineral availability from all test foods. The significantly low glycemic index foods (< 60 mmol × min/l) investigated were: macaroons (45.7 ± 3.0), carrot cake (51.8 ± 3.3) and brownies (60.1 ± 5.4) with 20–25% coconut flour. The test foods containing 15% coconut flour has a glycemic index ranging from 61 to 77 mmol × min/l. Among the test foods, pan de sal (87.2 ± 5.5) and multigrain loaf (85.2 ± 6.8) gave significantly higher glycemic index with 5% and 10% coconut flour. On the other hand, granola bar and cinnamon which contained 5% and 10% coconut flour, respectively gave a glycemic index ranging from 62 to 76 mmol × min/l and did not differ significantly from the test foods containing 15% coconut flour (P < 0.05). A very strong negative correlation (r = − 85, n = 11, P < 0.005) was observed between the glycemic index and dietary fiber content of the test foods supplemented with coconut. There was a significant reduction (%) in serum total and LDL cholesterol for: oat bran flakes, 8.4 ± 1.4 and 8.8 ± 6.7, respectively; 15% coconut flakes, 6.9 ± 1.1 and 11.0 ± 4.0, respectively; and 25% coconut flakes, 10.8 ± 1.3 and 9.2 ± 5.4, respectively (P < 0.05). Serum triglycerides were significantly reduced for all test foods: corn flakes, 14.5 ± 6.3%; oat bran flakes, 22.7 ± 2.9%; 15% coconut flakes, 19.3 ± 5.7%; and 25% coconut flakes, 21.8 ± 6.0% (P < 0.05). Results from the above study can be a basis in the development of coconut flour as a functional food.

Industrial relevance

The functionality of coconut flour in terms of prevention for risk of chronic diseases, e.g. diabetes mellitus, cardiovascular diseases (CVD) and colon cancer, revealed increase production of coconut and coconut flour. The production of coconut flour is very economical because it can be produced in a small or large scale. The raw material is obtained from the by-product (waste) of the coconut milk industry and the process and equipment used in its production is simple and cheap. Coconut flour as a good source of dietary fiber can be added to bakery products, recipes and other food products for good health.     

In vitro evaluation of physiological probiotic properties of different lactic acid bacteria strains of dairy and human origin

Eleven lactic acid bacteria strains of importance to the dairy industry were subjected to in vitro analyses to determine their probiotic potential. Seven strains were isolated from ewe’s and cow’s milk (Enterococcus faecalis – five –, Lactococcus lactis and Lactobacillus paracasei). Four were obtained from American Type Culture Collection (ATCC), isolated from cheese (Lactobacillus casei 393), human feces (L. paracasei 27092 and Lactobacillus rhamnosus 53103) and used in cheese making (L. lactis 54104). Although none of the strains was able to degrade mucin, all E. faecalis showed, at least, one transferable antibiotic resistance, which excluded them as candidates for addition to foods. Of the remaining six safe strains, L. lactis strains were more tolerant to low pH than Lactobacillus spp.; all were tolerant to pancreatin and bile salts and showed antibacterial activity. The highest level of adhesion to Caco-2 cells was observed with L. lactis 660, even higher than L. rhamnosus ATCC 53103 (recognized probiotic and used as control). The physiological probiotic properties of these strains, mainly isolated from dairy sources, are interesting in view of their use in cheese productions as starter and non starter cultures. The five LAB safe strains studied may have potential as novel probiotics in the dairy foods.     

Book reviews

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Book reviews

     

Effect of enterocin AS-48 in combination with high-intensity pulsed-electric field treatment against the spoilage bacterium Lactobacillus diolivorans in apple juice

Enterocin AS-48 was tested in apple juice against the cider-spoilage, exopolysaccharide-producing strain Lactobacillus diolivorans 29 in combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 μs and bipolar mode). A response surface methodology was applied to study the bactericidal effects of the combined treatment, with AS-48 concentration and HIPEF treatment time as process variables. At subinhibitory bacteriocin concentrations, microbial inactivation by the combined treatment increased as the bacteriocin concentration and the HIPEF treatment time increased (from 0.5 to 2.0 μg/ml and from 100 to 1000 μs, respectively). Highest inactivation (4.87 logs) was achieved by 1000 μs HIPEF treatment in combination with 2.0 μg/ml AS-48. While application of treatments separately did not protect juice from survivors during storage, survivors to the combined treatment were inactivated within the following 24 h of storage, and the treated samples remained free from detectable lactobacilli for at least 15 days at temperatures of 4 °C as well as 22 °C. The combined treatment could be useful for inactivation of exopolysaccharide-producing L. diolivorans in apple juice.     

Occurrence of Escherichia coli O157, O111 and O26 in raw ewe's milk and performance of two enrichment broths and two plating media used for its assessment

The occurrence of Escherichia coli O157, O111 and O26 in 159 raw ewe's milk samples was examined. Sample-aliquots were incubated simultaneously in TSB added with yeast extract (YETSB) and mTSB with novobiocin (N-mTSB). Serogroup-specific immunomagnetic separation (IMS) was then used and IMS beads were plated in a cefixime tellurite (CT)-containing media (CT-SMAC, CT-SBMAC and CT-RMAC for E. coli O157, O111 and O26, respectively) and E. coli O157:H7 chromogenic ID agar. A sweep of confluent growth from each medium was examined for the presence of E. coli O157 and O111 using PCR, and for E. coli O26 using a latex agglutination test. Enumeration of E. coli O157 and O111 was performed in the samples tested positive for the correspondent serogroup using the most probable number (MPN) method combined with PCR. Percentage occurrences of E. coli O157, O111 and O26 were 18.2, 8.2 and 5.7, respectively. Mean E. coli O157 and O111 levels were 0.22 and < 0.04 MPN/mL, respectively. Enrichment in YETSB resulted in higher detection rates of E. coli O157 and O26 than in N-mTSB. When YETSB was used as enrichment broth and for these last two serogroups, the analysis of the confluent growth from the CT-media gave more positive results than that from E. coli O157:H7-ID medium.     

Determination of anthocyanin content in C.V Monastrell grapes during ripening period using several procedures

The accumulation of anthocyanins in grape skin and their evolution during ripening were evaluated in Monastrell grapes grown at four different sites growing season. Of the different techniques used for this purpose, we used one chromatographic [high‐performance liquid chromatography (HPLC)] and three spectrophotometric (Saint‐Cricq, Fragoso‐García and Lamadon) methods. The grapes from two of the sites (Agüeros and Rubializas) presented much higher values of anthocyanin (1279 and 1207 mg kg^?1 respectively) compounds than the grapes from the other two sites. Of the different methods used, HPLC proved to be an invaluable tool for identifying and quantifying individual anthocyanins in a sample, while the Fragoso‐García technique was the best of the spectrophotometric methods for laboratories that do not have access to HPLC equipment. Application of principal component determination (PCA) to our experimental data resulted satisfactory classification of wines in terms of their geographical origin. High correlation coefficients were observed among the different spectrophotometric techniques (0.88 between Fragoso‐García and Saint Cricq; and 0.92 between Lamadon and Saint Cricq) and lower coefficients between HPLC and the spectrophotometric techniques.     

Free radical-scavenging activity of nonenzymatically-browned phospholipids produced in the reaction between phosphatidylethanolamine and ribose in hydrophobic media

The reaction of phosphatidylethanolamine (PE) and ribose (RI) in olive oil was studied in an attempt to both explore the possibilities of producing Maillard reaction in hydrophobic media and analyse the antioxidant properties of the formed compounds. When oil samples containing PE/RI mixtures were heated at a temperature higher than 90 °C, the oil rapidly developed browning, fluorescence, and free radical-scavenging activity, which was higher than the developed by the oil in the absence of added compounds or in the presence of only either PE or RI. These changes were a consequence of the formation of Maillard reaction products in the oil by reaction between PE and RI. Among them, the N-alkylpyrrole derivatives produced in this reaction could be determined by GC–MS after transpyrrolisation. Differently to Maillard products formed between carbohydrates and amino acids, the products of the reaction with aminophospholipids are more hydrophobic and, therefore, better candidates to be employed as lipophilic antioxidants in food products. Because of the different polarity of Maillard products between carbohydrates and either amino acids or aminophospholipids, Maillard reaction can be a useful procedure to obtain a wide range of antioxidants with different polarities to be employed in different food systems.     

Changes in phenolic compounds and colour in pale Sherry wines subjected to fining treatments

 Changes in the concentrations of hydroxybenzoic acids, hydroxycinnamic acids and their esters, monomeric and dimeric derivatives of flavan-3-ol, and flavonols, as well as in the UV-visible absorbances of pale Sherry wines were studied. The wines were subjected to four different fining treatments: casein + bentonite, casein + bentonite + activated charcoal, casein + bentonite + polyvinylpyrrolidone (PVPP) and casein + bentonite + Riduxhigh. Based on the results, the treatments including activated charcoal and PVPP were the most effective at decreasing the overall concentration phenolic compounds, with no significant difference between them. Likewise, these treatments provided the best results in relation to wine colour in the visible spectral region, and particularly at 420 nm, at which wavelength browning compounds are usually measured. Received: 24 March 1997 / Revised version: 11 June 1997     

Development of a polymerase chain reaction assay for species identification of goose and mule duck in foie gras products

Polymerase chain reaction amplification of a conserved region of the -actin gene has been used for the specific identification of goose (Anser anser) and mule duck (Anas platyrhynchos×Cairina moschata) foie gras. Universal primers were used for the amplification of a DNA fragment containing three introns and four exons of the -actin gene in goose and mule duck. Sequence analysis of the amplified fragments was necessary for the design of forward species-specific primers in the goose and mule duck -actin genes. The use of species-specific forward primers, together with a reverse universal primer, produced amplicons of different length, allowing clear identification of goose and mule duck foie gras samples. Analysis of experimental mixtures demonstrated that 1% of duck can be easily detected in goose foie gras using the PCR method developed here. This genetic marker can be very useful for the accurate identification of these two species in foie gras products.