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%

Faktor Kerentanan Food Fraud dan Mitigasinya : Studi Kasus Pada Produsen Susu Bubuk di Indonesia

Food fraud is one of the risks in the supply chain globalization. A complex and long supply chain withdifferent locations, cultures, business ethics, policies and surveillance systems are the contributing factorsto food fraud. This study aims to identify food fraud vulnerability factors in milk powder producers. Itwas conducted in two companies which uses powder and liquid milk as the raw materials which istypical in Indonesian powdered milk industry. The study steps consist of respondents determination,data collection and analysis, formulating mitigation strategies. The respondents were company’s headof departments and a government officer of the National Agency for Drug and Food. Data collectionand analysis were carried out with the Safe Supply Affordable Food Everywhere (SSAFE) tool, whilemitigation strategies was formulated through Focus Group Discussion. The results show that vulnerabilityto food fraud rooted from the opportunity factor, namely the easiness and availability of technologyto commit fraud, motivational factor namely the level of corruption and regulatory differences thataffect prices, control measures factors due to lack of supervision, employee integrity tests and preventionguidelines. Internally improving control measures within the company and guideline prevention fromthe government were mitigation measures to be done

Efektivitas Sanitizer Komersial Berbasiskan Asam Perasetat terhadap Biofilm Bacillus cereus

Bacillus cereus is known to have the ability to adhere and form biofilms on the surface of stainless steel that causes problems in the food industries. Bacterial biofilms generally can increase resistance to sanitizer treatment. This study aimed to evaluate the ability of peracetic acid-based commercial sanitizer to inactivate B. cereus biofilm on stainless steel (SS) surfaces. Biofilm of B. cereus ATCC 10876 was developed on SS surfaces and treated with 7 commercial peracetic acid-based sanitizers at their recommended dosages. Two sanitizers, i.e. B (peracetic acid and QAC) and F (peracetic acid and acidified water) showing the ability to inactivate B. cereus on solid media at concentration of 200, 400, and 800 ppm were further tested on biofilms with contact times of 1, 3, and 5 minutes. The 48 hours biofilms B. cereus contained 2.78-3.78 CFU/cm2. Both sanitizers B and F had significant effects in inactivating B. cereus biofilm. In general, sanitizer B could reduce more biofilm bacteria at any contact time than sanitizer F. Use of 200 ppm of sanitizer B or F 5 minutes could inactivate 3.04 log CFU/cm2 and 2.68 log CFU/cm2 biofilm, respectively. Exposure of B. cereus biofilm to peracetic acid-based sanitizer resulted in the damage of the extracellular matrix of the biofilms. This study showed that commercial sanitizers containing peracetic acid and quaternary ammonium compounds were effective in inactivating B. cereus biofilms

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

Rapid Food Hygiene Inspection Tool (RFHiT) to assess hygiene conformance index (CI) of street food vendors

Street-vended food is a popular choice among consumers as they are cheap, convenient and easily accessible, especially in Asia. Studies have assessed street food vendors’ food safety and microbiological quality of street-vended foods and overall findings revealed gaps and inconsistencies in hygiene practices. High numbers of street food vendors vs low numbers of environmental health officers and limited time remains a challenge in most developing countries in assessing the hygiene compliance of food services. Most inspections rely on paper-based assessments of the cleanliness and hygiene practices of staff. This study developed a Rapid Food Hygiene Inspection Tool (RFHiT) to assess and calculate the hygiene conformance index (CI) of 95 street food vendors. RFHiT allows rapid assessment as it takes less than 20 minutes to assess each street food vendor. 51.30% of the street food vendors were rated as moderately clean whilst 14.25% were rated as poor and 0.95% as very poor. 20% of the vendors achieved a good rating with six street-food vendors rated as excellent. The proposed tool further demonstrated practical implications of using the rapid inspection tool to assess actual hygienic practices of street food vendors, thus reducing the Hawthorne effect among food handlers

Petunjuk sederhana : memproduksi pangan yang aman/ hariyadi

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