Package of the Autumn 2021

Background and Objective:

Fermentation is one of the best methods for in-situ generation of aromas in breads. However, generating desirable flavors needs controlling several effective factors. In this study, optimal conditions for the production of honey and rose-like aromas were investigated by fitting a quadratic model using response surface method. To the best of the authors’ knowledge, no study has used this method for the high-efficiency production of flavor compounds in sourdough.

Material and Methods:

In the present study, headspace solid-phase microextraction-gas chromatography mass spectrometry was used to demonstrate ability of Kluyvero-myces marxianus and Leuconostoc mesenteroides co-culture to produce 2-phenyl ethyl acetate and 2-phenyl ethyl alcohol in sourdough. Therefore, experiments were developed using response surface method and six parameters of dough yield, temperature, time, fructose, phenylalanine and bran proportions. Volatiles were collected from sourdough using headspace solid-phase microextraction method, followed by measuring the extracted volatile compounds using gas chromatograph connected to a mass selective detector.

Results and Conclusion:

Results suggested that fermentation was optimum at 25 ℃ for 66.5 h with dough yield, 400; fructose, 6%w v^-1; phenylalanine, 0.3% w v^-1 and bran, 20% w w^-1 for the production of rose and honey-like aromas with high efficiency (2-phenyl ethyl alcohol 127.1 mg l^-1 and 2-phenyl ethyl acetate 70.7 mg l^-1). Assessment of the baking and storage effects on the selected aroma compounds showed that although sharp decreases occurred in their concentrations due to the oven temperature, they were still detectable in the bread after 3 days of storage. Based on the optimized model, it can be concluded that increasing time and decreasing fermentation temperature led to the strengthening of aroma production. Furthermore, phenylalanine and fructose strongly affected development of the target aromas.

Conflict of interest: The authors declare no conflict of interest.

Abstract

Background and Objective: In the authors’ previous study, four unique Lactobacillus strains (Lactobacillus plantarum Dad-13, Lactobacillus plantarum Mut-7, Lactobacillus plantarum T-3 and Lactobacillus paracasei SNP-2) from Indonesian fermented foods and healthy feces have been studied as probiotic agents. In the current study, antibiotic resistance phenotypes of the highlighted Lactobacillus plantarum and Lactobacillus paracasei against eight antibiotics (amoxicillin, tetracycline, erythromycin, clindamycin, chloramphenicol, streptomycin, kanamycin, ciprofloxacin) and antibiotic resistance genes of these strains were investigated.

Material and Methods: The bacterial antibiotic susceptibility to eight antibiotics was assessed using disk diffusion method. Genome sequencing was carried out using NovaSeq 6000 sequencing platform. Genome was annotated using Rapid Annotation using Subsystem Technology v.2.0. Each group of the predicted products of resistance genes was further aligned using multiple sequence comparison by log-expectation and their functions were verified using comprehensive antibiotic resistance database 2020.

Results and Conclusion: All strains showed resistance to aminoglycoside and ciprofloxacin but sensitive to amoxicillin, clindamycin and erythromycin. Resistance to chloramphenicol and tetracycline varied within the strains. Two strains were sensitive and others were intermediate resistance to chloramphenicol. One strain was resistant to tetracycline, while the other three strains demonstrated intermediate resistance to the antibiotic. Genome sequence of the four strains verified the presence of the tetracycline, β-lactamase and ciprofloxacin resistance genes as well as multidrug resistance efflux systems. Occurrence of the resistance genes was correlated to the phenotype results, except for amoxicillin and aminoglycosides. Rapid Annotation using Subsystem Technology annotation showed that all Lactobacillus strains did not include transposable elements, gene transfer agents and plasmid linked functions; thus, horizontal transfer of the antibiotic resistance genes unlikely occurred.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: Conventional applied techniques used for detecting pathogenic microorganisms that generally are based on plating, serological and biochemical assays are unreliable and expensive while lacking sensitivity and specificity compared to new analytical methods. Investigation of reliable and rapid analytical diagnosis methods seems a necessity today. In the present study, a high accurate method was developed aiming to pre-concentrate and improve identification of Staphylococcus aureus as a major bacterial human pathogen by using a molecular imprinted polymer (MIP) based membrane.

Materials and Methods: Cellulose acetate was used as the basic membrane with a pore size of 1.2 μm, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linking monomer, antibody buffer medium as the template molecule, and 2,2'-Azobis(2-methylpropionitrile) as the initiator agent. After selecting the best membrane composition resulting from the optimum ratio of antibody to imprinted monomer, electron microscopy testing was used to evaluate the characterization and stabilization of the molecular imprinting of templates on the membrane.

Results and Conclusion: According to the results, the suspension of Staphylococcus aureus with a dilution of 3×10⁵ after being adjacent to MIPs modified membranes had the highest bacterial mass absorption in MIP₄ filter and reduced to a level of 1.3×10⁴. The manufactured nano membrane could lead to a significant development in quality control of food industry compared to traditional methods due to a very shorter required time of bacterial mass diagnosis with a very higher accuracy.

Keywords: Antibody; Molecular Imprinted Polymer; Nano Membrane; Staphylococcus aureus

Background and Objective:

Black soybean (Glycine max (L.) Merr.) Detam-1 variety includes high quantities of isoflavone majorly in glucoside form; in which, the biochemical antioxidant activity was lower than that in isoflavone aglycone form. Fermentation by lactic acid bacteria can increase antioxidant activity and isoflavone aglycone of black soymilk. However, the biochemical ability is strain-dependent and sucrose or skim milk supplementation during processing may affect this ability. The objective of the current study was to investigate antioxidant properties of the fermented black soymilk and fermented black soymilk supplemented with 2% sucrose or skim milk using three Indonesian indigenous lactic acid bacteria, namely Lactobacillus plantarum WGK 4, Streptococcus thermophilus Dad 11 and Lactobacillus plantarum Dad 13. Furthermore, cell growth and acid production were investigated.

Material and Methods:

Fermentation of black soymilk and black soymilk supplemented with 2% sucrose or skim milk was carried out using three indigenous lactic acid bacteria at 37 °C for 18 h. Viable cell, pH, titratable acidity, β-glucosidase activity, isoflavone aglycone, total phenolic content and antioxidant activity of black soymilk were assessed at the beginning of the experiment and after 18 h of fermentation.

Results and Conclusion:

Results showed that all strains could grow (9 log CFU ml^-1) and produce acid in black soymilk and black soymilk supplemented with 2% sucrose or skim milk. Fermentation increased isoflavone aglycone through β-glucosidase activity, which resulted in increased total phenolic content and antioxidant activity. Fermented black soymilk with no sucrose or skim milk exhibited the highest β-glucosidase activity (19.66-21.54 mU ml^-1), daidzein formation (62-74%), genistein formation (67-80%) and antioxidant capacity (32.81-38.47%). All three lactic acid bacteria strains enhanced antioxidant activity and isoflavone aglycone of the black soymilk. Sucrose or skim milk addition did not affect the cell growth but increased acid production and decreased β-glucosidase activity and isoflavone aglycone formation. These three lactic acid bacteria included similar abilities to enhance antioxidant activity and isoflavone aglycone formation in fermented black soymilk.

Background and Objective:

Ganoderma lucidum is one of the medicinal fungi frequently used as supplement. The intracellular polysaccharides of this fungus include high molecular weights and help strengthen the immune system. Furthermore, these polysaccharides act as antioxidants by inhibiting free radicals and enhancing activity of the enzymes. Addition of various elicitors to the fungi submerged culture media affects the cell growth and metabolite production. Fungal extracts are one of these elicitors.

Material and Methods:

In this study, Ganoderma lucidum was first cultured in various culture media to investigate the base media. Using three various methods (soaking the fruit body in water, disintegrating the fruit body with a blender and boiling the fruit body), Agaricus bisporus fruit body extract was prepared as elicitor and the extract with the highest sugar content was used. For the optimization of growth and antioxidant activity of the intracellular polysaccharides, effects of six independent factors were investigated using Placket-Burman method, including Agaricus bisporus extract, peptone, maltose, pH, vitamin B₁ and CaCl₂. Response surface method was used to optimize three factors of vitamin B₁, Agaricus bisporus extract and maltose. Then, stirred tank bioreactor was used to culture Ganoderma lucidum.

Results and Conclusion:

The YPG culture medium was selected as the base medium based on mycelial growth and antioxidant activity of the intracellular polysaccharides (IC₅₀). Sugar content of the Agaricus bisporus extract was 30.66 µg.ml^-1. Placket-Burman method revealed that the extracts of Agaricus bisporus, maltose and vitamin B₁ significantly increased antioxidant activity of the intracellular polysaccharides. After optimizing these factors using RSM, the IC₅₀ was reported as 1.047 mg.ml^-1. Ganoderma lucidum cultivation in bioreactor significantly increased the cell growth (5.29 g.l^-1). Intracellular polysaccharides included an IC₅₀ of 1.14 mg.ml^-1, which was significantly higher than that the intracellular polysaccharides included in YPG culture media.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective:

Food wastes cause economic losses and environmental problems. Hence, ability to transform food wastes into high-value added products is highly attractive. The aim of this study was to produce melanin pigments by fermentation that include wide potential uses in agriculture, cosmetics and pharmaceutical industries using domestic wastes such as melon peel, watermelon peel and carrot peel and industrial by-products such as whey and molasses.

Material and Methods:

Two Aureobasidium pullulans strains were assessed for melanin production. Fourier-transform infrared spectroscopy, scanning electron microscope, zeta potential, ultraviolet absorbance and solubility assays were carried out to characterize produced melanin nanoparticles.

Results and Conclusion:

The highest intracellular (0.19 g l^-1) and extracellular (3.52 g l^-1) melanin concentrations were produced by Aureobasidium pullulans NBRC 100716 using carrot peel extracts as fermentation media. Results of characterization were compared with those of synthetic melanin used as standard and the produced nanoparticles were validated. Particle sizes of the nanoparticles ranged 10-760 nm with negative charges, as suggested by previous literature. Results showed that carrot peel was a good candidate, which could be used for the production of high value-added melanin. When carrot peel extract was used as a fermentation medium, characteristics of the melanin produced by Aureobasidium pullulans NBRC 100716 strain were similar to those of synthetic melanin.

Conflict of interest: The authors declare no conflict of interest

Background and Objective:

Edible film is one of the solutions for food packaging that carry antimicrobial and antioxidant compounds, usually found in Medinilla speciosa fruits. The objective of this study was to assess effects of Medinilla speciosa fruit extract on physical, chemical and bioactivity of edible films as well as effects of coating on sausage quality during storage.

Material and Methods:

The edible film included 2% w w^-1 chitosan, 2% w w^-1 sorbitol and Medinilla speciosa fruit extract. Variations of Medinilla speciosa extract included 0, 2.5, 5 and 10% (w w^-1), while the storage temperature included 4 and 27 ^oC. Seven parameters of edible film characteristics were assessed, including tensile strength, elongation, water vapor permeability, antimicrobial and antioxidant activities, surface microstructure and Fourier-transform infrared response. Parameters assessed in storage treatment included total plate count, yeast mold count and thiobarbituric acid reactive substances. Data were analyzed using Kruskal-Wallis test. Organoleptic characteristics were analyzed using Friedman test and SPSS Software.

Results and Conclusion:

Results showed that the higher the concentration of Medinilla speciosa extract was, the higher the value of tensile strength, water vapor permeability and antioxidant activity and lower the elongation value were. The film control with 0% Medinilla speciosa extract was the only film that met Japanese standard for the water vapor permeability value, including 6.74 gm^-2 h^-1. Furthermore, shelf life of sausages coated with edible films revealed that the higher the concentration of Medinilla speciosa extract was, the lower the total plate count, yeast mold count and thiobarbituric acid reactive substances values were. Study demonstrated that the Medinilla speciosa extract edible film inhibited microbiological and oxidative damages. ​Oon Day 15 of storage, sausages coated with edible films with 10% Medinilla speciosa extract included lower total plate count, yeast mold count and thiobarbituric acid reactive substances values, respectively including 2.4 ±0.02 log CFU g^-1, 1.3 ±0.08 log CFU g^-1 and 13.38 ±0.22 mg malonaldehyde kg^-1 sausage, compared to the control film. Organoleptic assessment showed no major differences in consumer acceptance. In conclusion, edible film with 10% Medinilla speciosa extract is the best physical, chemical and bioactivity film. Moreover, this film extends the sausage shelf life.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective:

Beer is one of the most consumed beverages worldwide that can be used to transfer probiotics to the host. The aim of this study was to generally review technological parameters incorporated in the production of probiotic beers. Probiotic beer production needs solving technical problems that are linked to processing stages. Although use of probiotics in fermented dairy products has been searched in available scientific literatures, beer is a relatively novel matrix for the incorporation of probiotics and hence a review on its capability as a probiotic carrier can be advantageous. Therefore, objective of the recent review was to investigate the most recent method for the production of probiotic beers. Furthermore, factors affecting the viability of probiotics in the final product were studied.

Conclusion:

Scientific literatures verified that probiotic beers could be produced with a few modifications from the non-probiotic beers. As probiotic species include poor growth abilities and probiotic viability is the most important factor considering a product as a probiotic product, multiple criteria for the production of probiotic beers include selecting an alcohol and acid-tolerant probiotic strain, administration of encapsulated probiotics, eliminating thermal and filtration processes, controlling oxygen concentration during fermentation process and after inoculation with probiotic strain, inhabiting severe acidic condition during the probiotic beer production and holding temperature below 5 ˚C during storage and transportation. However, several researches are needed to clarify limiting factors to achieve optimum conditions for the production of appropriate probiotic beers. However, incorporation of nonviable probiotics as alternate germs can be considered as a novel method for the production of health improving beers.

Conflict of interest: The authors declare no conflict of interest.