Preparation and characterization of carboxymethyl cashew gum grafted with immobilized antibody for potential biosensor application

This report details the design of carboxymethylated cashew gum (CG) as a platform for antibody (Ab) immobilization, which can then be used as a biosensor for bacteria detection. The CG was isolated and characterized, followed by conversion to carboxymethyl cashew gum (CMCG). The CMCG film was a viable support for antibody immobilization; it was electrodeposited on gold surface using the cyclic voltammetry technique, applying a potential sweep from -1.0 V to 1.3 V with a scan rate of 50 mV s^-1 and 10 scans. The COOH groups on the surface of the film were critical in promoting Ab bonding. The immobilization of the Ab was mediated by protein A (PrA) for recognition of the antigen. Voltammetry studies were used to monitor the antibody immobilization. Finally, the analytical response of the CMCG-PrA-Ab system was evaluated with the chronoamperometry technique and was found to detect Salmonella Typhimurium bacteria rapidly and efficiently.

SUN-265 Performance of Basal and GnRH Analog-Stimulated LH Levels Assessed by an Electrochemiluminescence Assay in Girls with Central Precocious Puberty

Background: The laboratory evaluation of patients with precocious puberty is useful to differentiate central precocious puberty (CPP) from isolated thelarche (IPT) and peripheral precocious puberty (PPP). Ultrasensitive immunoassays, such as electrochemiluminescence (ECLIA), improved sensitivity and specificity of basal and GnRH-stimulated LH levels to establish the differential diagnosis among these conditions. Aim: To establish the diagnostic value of basal and GnRHa-stimulated LH values and basal estradiol assessed by ECLIA in pubertal disorders. Patients and Methods: We included 38 girls with pubertal disorders (28 CPP, 8 IPT, and 2 PPP). Their medical records were systematically revised. Clinical and hormonal data [basal and GnRH analog -stimulated LH levels (2 hs after leuprorrelin 3.75 mg) and basal estradiol] were analyzed. Gonadotropins and estradiol levels were assessed by ECLIA (Roche, Cobas e 6000). The functional sensitivity of the assays was 0.15 IU/L for LH, FSH 0.6 IU/L for FSH and 17 pg/mL for estradiol. Basal gonadotropins and estradiol were also assessed in a control group composed by 16 prepubertal and 19 pubertal girls. The cutoff values for basal and GnRH analog- stimulated LH for diagnosis of CPP was set at < 0.3 IU/L and 8 IU/L, respectively (1). Results: The mean age of girl with CPP, IPT, and PPP at the first clinical visit was 8 ± 0.9yr (5.25- 9.6 yr), 4.25± 2.6 (0.7-7.8 yr), and 5.12±2.9 (3.1 -7.1 yr), respectively. All CPP girls presented breast development ranging from B2 to B5, whereas IPT group B2-B4 and PPP group (B2). Pubarche was presented in 86% of girls with CPP (PH 2- PH 5). Only one girl in IPT group also presented pubarche (PH3), associated to zinc oxide cream use and none in PPP group presented pubarche. The mean basal LH was 3.4 ± 1.6 (<0.1- 8.6 IU/L), 0.15 ± 0.03 (< 0.15-0.2 IU/L), and <0.15 IU/L for CPP, IPT, and PPP, respectively. In CPP group, GnRHa- stimulated LH and basal estradiol levels were 6 ± 2.8 (4-61.4 IU/L) and 21 ± 17 (<17- 90 pg/ml), respectively. The sensitivity and specificity of basal and GnRHa-stimulated LH values for diagnosis of CPP was 64.7 % and 100%, respectively. However, the cutoff of 5 IU/L for GnRHa-stimulated LH improved sensitivity to 87.5% but with lower specificity of 67%. Estradiol was undetectable (<17 pg/ml) in 48% girls with CPP. In the IPT and PPP groups, basal LH <0.3 IU/L was detected in all patients. In the control group, all but one prepubertal girl had basal LH <0.15 IU/L. In addition, basal estradiol > 17 pg/ml was present in two girls from control prepubertal group. In the control pubertal group (B3-B4), mean basal LH was 4.2± 2.3 (<015- 8.8 IU/L) and basal estradiol was 61 ± 34 (<17-135pg/mL). Conclusion: The diagnostic value of basal and GnRH-stimulated LH levels assessed by ECLIA to diagnosis CPP is limited and must be interpreted together with clinical data. Reference: (1) Freire AV et al, Clin Endocrinol (Oxf), 2013.

Acetic Acid Bacteria in the Food Industry: Systematics, Characteristics and Applications

The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of food and beverages, such as vinegar and kombucha. The ability to oxidise ethanol to acetic acid also allows the unwanted growth of AAB in other fermented beverages, such as wine, cider, beer and functional and soft beverages, causing an undesirable sour taste. These bacteria are also used in the production of other metabolic products, for example, gluconic acid, l-sorbose and bacterial cellulose, with potential applications in the food and biomedical industries. The classification of AAB into distinct genera has undergone several modifications over the last years, based on morphological, physiological and genetic characteristics. Therefore, this review focuses on the history of taxonomy, biochemical aspects and methods of isolation, identification and quantification of AAB, mainly related to those with important biotechnological applications.

Processamento e estabilidade de uma bebida de caju e yacon durante o armazenamento sob refrigeração

Resumo O objetivo do presente trabalho foi avaliar a estabilidade de uma bebida de caju e yacon durante o armazenamento sob refrigeração. A bebida, composta por polpa de caju e extrato de yacon (proporção 1:1, v/v), foi pasteurizada a 85 °C por 90 segundos e armazenada sob refrigeração (5 °C). No tempo inicial e a cada 45 dias do período de estocagem, foram determinados os teores de compostos bioativos (ácido ascórbico - AA e polifenóis extraíveis totais - PET), a atividade antioxidante total (AAT), os sólidos solúveis totais (SST), a acidez titulável (AT), o pH e a cor (L*, a* e b*). Após 225 dias de estocagem, a bebida apresentou diminuição expressiva da sua AAT, medida pelo método FRAP (Ferric Reducing Antioxidant Power), de aproximadamente 22%, assim como houve queda nas concentrações de AA e PET, em torno de 20 e 16%, respectivamente. A bebida atendeu ao padrão estabelecido pela legislação brasileira para coliformes a 45 °C e Salmonella sp. (ausência/25 mL); porém, em 135 dias de armazenamento, a bebida apresentou contagem de bolores e leveduras superior a 104 UFC/mL. Neste sentido, embora a bebida tenha apresentado níveis consideráveis de compostos bioativos e AAT durante os 225 dias de armazenamento refrigerado (5 °C), recomenda-se que o produto seja armazenado por até 90 dias sob refrigeração (5 °C), período em que a bebida manteve seus componentes bioativos e boa qualidade microbiológica e sensorial.

Stability of a functional beverage composed by tropical fruits and yacon (Smallanthus sonchiyo- lius) under refrigerated storage

The development of beverages with functional properties must consider the preservation of the bioactive or functional properties during storage. For this reason, the aim of this study was to evaluate the stability of a functional beverage of tropical fruits and yacon, stored under refrigeration. The beverage, composed by 50% of yacon and 50% of a blended tropical fruits (camu-camu, acerola, cashew-apple, yellow mombin, acai and pineapple), was pasteurized (90 seconds/ 85⁰C) and stored under refrigeration (5⁰C). After processing and on 45 day intervals until the end of storage, were assayed the bioactive compounds (ascorbic acid and total extractable polyphenols), antioxidant activity, total soluble solids, titratable total acidity, pH, color (L*, a* and b*), total sugar content, sucrose, glucose and fructose, and nd the physical and chemical analyzes were limited by decreased total antioxidant activity and their bioactive components. The beverage showed relative physical and chemical quality during storage period, and in the 225 days of storage, the total extractable polyphenols and total antioxidant activity showed a significantly decline, and thus , these parameters were evaluated only until this period. However, the main limitation for the beverage storage was due to. sensory acceptability and microbiological safety, which although in accordance with Brazilian legislation, limited storage period for 90 days.

Toxigenic status of Staphylococcus aureus isolated from bovine raw milk and Minas frescal cheese in Brazil

A group of 291 Staphylococcus aureus isolates from mastitic cow's milk (n = 125), bulk tank milk (n = 96), and Minas frescal cheese (n = 70) were screened for staphylococcal enterotoxin (SE) genes (sea, seb, sec, sed, see, seg, seh, sei, selj, and sell) and for the tst-1 gene encoding staphylococcal toxic shock syndrome toxin 1 by PCR assay. A total of 109 (37.5%) of the isolates were positive for at least one of these 11 genes, and 23 distinct genotypes of toxin genes were observed. Of the S. aureus isolates bearing SE genes, 17 (13.6%) were from mastitic cow's milk, 41 (41.7%) were from bulk tank milk, and 51 (72.9%) were from Minas frescal cheese. The occurrence of exclusively more recently described SE genes (seg through sell) was considerably higher (87 of 109 PCR-positive strains) than that of classical SE genes (sea through see, 15 strains). The SE genes most commonly detected were seg and sei; they were found alone or in different combinations with other toxin genes, but in 60.8% of the cases they were codetected. No strain possessed see. The tst-1 gene was found in eight isolates but none from mastitic cow's milk. Macrorestriction analysis of chromosomal DNA from 89 S. aureus isolates positive for SE gene(s) was conducted with the enzyme SmaI. Fifty-five distinct pulsed-field gel electrophoresis patterns were found, demonstrating a lack of predominance of any specific clone. A second enzyme, Apa I, used for some isolates was less discriminating than Sma I. The high genotype diversity of potential toxigenic S. aureus strains found in this study, especially from Minas frescal cheese, suggests various sources of contamination. Efforts from the entire production chain are required to improve consumer safety.

Occurrence of Listeria monocytogenes in salami

Eighty-one samples of four different types of salami (Friolan, Hamburguese, Italian and Milanese), belonging to five brands, and purchased at Rio de Janeiro market, were evaluated for the occurrence of Listeria monocytogenes. The pathogen was detected in 13.3% of Italian type samples of salami, while L. innocua occurred in 6.5% of the Italian type and in 16.6% of the Milanese type. The remaining samples were negative for Listeria spp.