In vitro Antioxidant and α-Glucosidase Inhibitory Activities of Lactobacillus spp. Isolated from Indonesian Kefir Grains

Background and Objective: In this study, nine Lactobacillus kefiri and one Lactobacillus rhamnosus isolates with kefir grain origin have been demonstrated to include potentials as probiotics. The aim of this study was to investigate ability of the isolates to produce compounds with α-glucosidase inhibitory and antioxidant activities and identify peptides with MW of ≤ 3 kDa in cell-free supernatants. Material and Methods: All isolates were cultured in de Man, Rogosa and Sharpe broth media at 37 oC for 24 h. Assessment of α-glucosidase inhibitory and antioxidant activities was carried out on cell-free supernatants. Assessment of optimum incubation time was carried out on two isolates with the highest α-glucosidase inhibitory and antioxidant activities. The two isolates were used to ferment reconstituted skim milk. Cell-free supernatant of the fermented skim milk was fractionated using filters of 10 and 3 kDa. Then, peptides in fractions of ≤ 3 kDa were identified. Results and Conclusion: The highest α-glucosidase inhibitory activity was seen in Lactobacillus rhamnosus BD2 and Lactobacillus kefiri YK4 as 73.58 and 64.31%, respectively. The highest antioxidant activity was observed in Lactobacillus kefiri JK5 and Lactobacillus kefiri JK17 as 44.31 and 41.57%, respectively. When Lactobacillus rhamnosus BD2 and Lactobacillus kefiri YK4 were cultured in reconstituted skim milk, their α-glucosidase inhibitory activities respectively decreased to 25.72 and 36.16% while the antioxidant activities respectively increased to 74.53 and 80.92%. Fractionation of the cell-free supernatants from fermented reconstituted skim milk of Lactobacillus kefiri YK4 showed that the highest antioxidant activity was included in fractions greater than 10 kDa. Although fractions of 3 kDa or less exhibited quite high antioxidant activities. Identification of peptides in fractions of 3 kDa or less showed that the peptides were mostly derived form β-casein. Of these peptides, two peptides with sequences of FPPQSV and YQEPVLGPVRGPFPIIV have been reported to include antioxidant activities. Conflict of interest: The authors declare no conflict of interest

SINTASAN Cronobacter sakazakii pGFPuv SELAMA PENYIMPANAN JAGUNG PIPILAN BERKADAR AIR AWAL BERBEDA DI BERBAGAI RH

Cronobacter sakazakii is an opportunistic foodborne pathogen reported to cause necrotizing enterocolitis, bacteremia, and meningitis in certain groups of infant. C. sakazakii has been reported to survive at low aw or dryness. Presence of wild-type C. sakazakii in dry product is difficult to be distinguished from naturally occuring C. sakazakii. A pGFPuv mutant of C. sakazakii has been reported to have similar growth pattern, thus has the potential to be used in further investigation. The study aimed to evaluate the effect of initial moisture content and relative humidity (RH) on the survival rate of C. sakazakii pGFPuv in corn kernels during storage at room temperature. The study consists of drying corn kernels to achieve moisture contents of 12 and 16% (w.b), inoculation of C. sakazakii pGFPuv, and storage at RH 50, 70 and 90% for 12 weeks. Every two week, corn kernels were sampled and the moisture content was measured using oven method, water activity was measured with aw meter, and total C. sakazakii pGFPuv was enumerated by spread plate method. Meanwhile, total bacteria, mold and yeast were enumerated by pour plate method. Corn kernels achieved equilibrium moisture content and aw after two weeks of storage. The number of C. sakazakii decreased rapidly during storage at RH 70 and 90%, however they could survived at RH 50% for 12 weeks, especially when the initial moisture content was 16%. The total bacteria decreased by 3.5-3.9 Log CFU/g during storage at three RHs, but mold and yeast increased rapidly at RH 90%

Cronobacter sakazakii MEMASUKI KONDISI VIABLE BUT NONCULTURABLE SELAMA PEMBENTUKAN BIOFILM

Studies show that nonsporeformer food-borne pathogens may enter a viable but nonculturable (VBNC) state under stress conditions. This research aimed to study the ability of Cronobacter sakazakii to enter a VBNC state during biofilm formation on stainless steel (SS) surfaces and its resuscitability. C. sakazakii YRt2a pGFPuv mutant and wildtype (WT) originally isolated from powder infant formula (PIF) were used in this study. Biofilms were developed on SS surfaces in 1/10 Trypticase Soy Broth (TSB). Culturability of the biofilms was monitored by swabbing and plating the WT or mutant sessile cells onto Trypticase Soy Agar (TSA) or TSA containing 100 μg/mL ampicillin (TSAA), respectively. Meanwhile, their viability was measured using direct microscopic (DMC) count based on green fluorescence for mutant isolates and direct viable count (DVC) for the WT using a fluorescence microscope. Biofilm of C. sakazakii pGFPuv mutant on SS entered VBNC state after 25 days of incubation, while the WT C. sakazakii biofilms was still culturable until day 63. Sodium pyruvate in solid and liquid medium was not able to resuscitate the biofilm cells of C. sakazakii pGFPuv in VBNC state. C. sakazakii pGFPuv mutants enter VBNC state faster than the WT isolates. Depleted nutrient is thought to drive biofilm of C. sakazakii pGFPuv to enter VBNC

Penghambatan Produksi Aflatoksin dari Aspergillus flavus oleh Kapang dan Khamir yang Diisolasi dari Ragi Tempe

This research was carried out to study the inhibition of aflatoxin production of Aspergillus flavus by moulds and yeasts isolated from ragi tempe. The result showed that moulds found in the ragi tempe consisted of Rhizopus oligosporus, R. oryzae, R. cohnii, Mucor rouxii, Rhizomucor pusillus, Aspergillus niger and miselia sterilia. Yeasts found in the samples were Candida sp1, Candida sp2 and Trichosporon sp. Twelve mould, and yeast isolates were chosen to determine their ability on inhibition of aflatoxin production. Aspergillus flavus alone or in association with each of these isolates were inoculated in Potato Dextrose Broth and analysed for aflatoxin production at day 10. All combinations yielded less aflatoxin than the single culture of A. flavus. All isolates tested could inhibit aflatoxin production. The highest inhibition was shown by Candida sp1 (99,96%)

Characterization of Ozone Distribution in Distilled Water and Coconut Water Produced Using a Double Dielectric Barrier Discharge Machine

Ozone produced using plasma technology can act as an antimicrobial agent that could be applied in a sterilization process. A Double Dielectric Barrier Discharge (DDBD) machine has ability to produce ozone in sufficient amount for microbial inactivation. The objective of this study is to characterize the ozone distribution expressed as dissolved ozone in distilled water and coconut water produced using a DDBD machine. The information can be useful for industries to design a commercial sterilization process. The results shows that an oxygen flow rate of 0.2 L/min produces the highest ozone concentration, i.e. 3440 mg/L. In addition, the capacity of the machine is relatively similar to all off oxygen flow rate, i.e., 41.28-43.2 g/hour. The oxygen flow rate of 0.2 L/min produces the highest dissolved ozone concentration, i.e. 0.42 mg/L distilled water. This oxygen flow rate is followed by its best kinetic model based on its linear portion during dissolved ozone penetration. A zero order model could describe this penetration process well, including its best k value of 0.0292 mg/L per minute with the highest dissolved ozone concentration among other oxygen flow rates. Besides, distilled water could represent dissolved ozone penetration in coconut water. Ozone gas and dissolved ozone concentration have possitive corellation with R-square value of 0.8934

Petunjuk sederhana : memproduksi pangan yang aman/ hariyadi

iv, 123 hal.: ill.; tab.; 23 cm

HACC (Hazard Analysis Critical Control Point) : pendekatan sistematik, pengendalian keamanan pangan/ Dewanti

viii, 144 hal.: ill.; tab.; 22 c

Inaktivasi Bakteri Patogen Planktonik dan Biofilm oleh Sanitaiser Komersial

Cleaning and sanitizing are important aspects in providing quality and safe foods. In the US, contaminated equipment is the third most important factor contributing to foodborne disease outbreaks. The objective of this study was to evaluate the effectiveness of commercial sanitizers against planctonic cells and biofilms of pathogenic bacteria Salmonella Typhimurium and Staphylococcus aureus. Commercial sanitizers used in this study were single sanitizers (quaternary ammonium, peroxy acetic acid, coconut fatty acid) and combined sanitizers (Oxyquart®, Bioclean 520®, Bioclean 540®) at the recommended application concentrations. Of the sanitizers tested on planctonic cells, peroxy acetic acid at 100 ppm as well as Oxyquart® and Bioclean 540® at concentrations of 0.010% are effective against S. Typhimurium; while Oxyquart® at a concentration of 0.005% is the most effective sanitizer against S. aureus. The study also shows that Oxyquart® is more effective against biofilms and capable of inactivating 3.94-5.02 log CFU/cm2 of S. Typhimurium or S. aureus biofilm.

Estimasi Risiko Okratoksin A dari Konsumsi Kopi Bubuk di Indonesia

Ochratoxin A (OTA) is a nephrotoxic and carcinogenic mycotoxin that can be found in coffee. This study aimed to obtain the processing steps commonly applied by coffee shops in Indonesia, calculate the level of OTA in coffee bean and ground coffee, and the risk estimate of OTA exposure from ground coffee in Indonesia. The processing steps were determined through an online survey while the level of OTA in coffee was calculated from available references. The consumption level of ground coffee was determined from the Indonesia total diet study report and the exposure assessment was carried out by deterministic approach. The risk estimates were expressed as % risk towards provisional tolerable weekly intake (PTWI) and margin of exposure (MOE). Based on the survey of coffee shops (n=20), ground coffee is commonly processed using dry method consisting of cherries sorting, sun drying, roasting and grinding. Ground coffee was the most common coffee consumed by adults. Based on references from countries with climate similar to Indonesia, the level of OTA in coffee bean ranged from 0.033 to 168 μg/kg with an average of 12.25 μg/kg and 0.018-55 μg/kg in ground coffee averaging at 5.60 μg/kg. The individual exposure to OTA from drinking coffee is 0.014-0.744 ng/kg bw/day. The risk estimates shows that risk of ochratoxin A from ground coffee consumption is low, with risk percentage of <100 % provisional tolerable weekly intake (PTWI) and a MOE of higher than 10000 for all age groups. The study suggested that adults (19-55 years) have higher exposure and risk than the other age groups