Volume 58, Issue No. 2

https://doi.org/10.17113/ftb.58.02.20.6439

SPME-GC-MS and Multivariate Analysis of Sensory Properties of Cheese in a Sack Matured with Probiotic Starter Cultures

Deni Kostelac¹, Marija Vrdoljak², Ksenija Markov¹, Ivančica Delaš³, Tjaša Jug⁴, Jasenka Gajdoš Kljusurić¹, Željko Jakopović¹, Iva Čanak¹, Marko Jelić² and Jadranka Frece¹*

¹Faculty of Food Technology and Biotechnology, Department of Biochemical Engineering, Laboratory for General Microbiology and Food Microbiology, Pierottijeva 6, 10000 Zagreb, Croatia

²Polytechnic ˝Marko Marulić˝, Petra Krešimira IV 30, 22300 Knin, Croatia

³School of Medicine, University of Zagreb, Department of Chemistry and Biochemistry, Šalata 3, 10000 Zagreb, Croatia

⁴Agricultural and Forestry Institute of Nova Gorica, Agrochemical Laboratory, Pri hrastu 18, 5000 Nova Gorica, Slovenia

Article history:

Received: 8 July 2019

Accepted: 25 May 2020

Key words:

traditional cheese, cheese ripening, probiotic bacteria, starter culture, aromatic profiles

Summary:

Research background. Cheese in a sack is a traditional cheese produced in Croatia. Types of cheese with similar production technology are made in other countries but chemical and microbiological composition varies between regions. Traditionally, cheese in a sack is produced without the addition of starter cultures. Addition of beneficial probiotic cultures to numerous dairy products has documented advantages. Effects that the addition of probiotic bacteria to traditional cheese have on aroma compounds and sensory properties have not been fully investigated. The aim of this study is to determine the sensory properties and differences in the aromatic profiles between cheese samples ripened in a lambskin sack, produced traditionally without the addition of any starter culture, or with the addition of probiotic bacteria.

Experimental approach. In this study, cheese in a sack was produced with the addition of probiotic cultures Lactobacillus plantarum B and L. lactis ssp. lactis S1. During ripening volatile aroma compounds were analysed with a solid-phase microextraction gas chromatography-mass spectrometry. Sensory properties were evaluated by trained tasters who are familiar with the traditional taste of the cheese from a sack. The results of aroma composition and taste scores were then compared using factorial and principal component analyses.

Results and conclusions. Chromatography showed differences in the composition of aroma compounds and the sensory properties between the cheese produced with Lactobacillus starter cultures and the control cheese, traditionally produced without a starter culture. The addition of probiotic cultures L. plantarum B and L. lactis ssp. lactis S1 resulted in products with better sensory properties and chemical profile of volatile aromatic compounds.

Novelty and scientific contribution. This study investigates the usage of naturally present probiotic cultures as starter cultures in cheese in a sack production. Their effects on aroma profiles and sensory characteristics have been compared for the first time using factorial and principal component analyses.

https://doi.org/10.17113/ftb.58.02.20.6223

Supplement

Lovastatin Production by Aspergillus sclerotiorum Using Agricultural Waste

Jutarut Iewkittayakorn^1*, Kannika Kuechoo¹, Yaowapa Sukpondma², Vatcharin Rukachaisirikul², Souwalak Phongpaichit³ and Wilaiwan Chotigeat^1,4

¹Department of Molecular Biotechnology and Bioinformatics, Faculty of Science, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand

²Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand

³Department of Microbiology, Faculty of Science, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand

⁴Center for Genomics and Bioinformatics Research, Faculty of Science, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand

Article history:

Received: 29 January 2019

Accepted: 15 July 2020

Key words:

agricultural waste, Aspergillus sclerotiorum, lovastatin, solid-state fermentation, soya bean sludge

Summary:

Research background. Lovastatin is a well-known drug used to reduce hypercholesterolaemia. However, the cost of lovastatin production is still high. Therefore, alternative low-cost carbon sources for the production of lovastatin are desirable.

Experimental approach. Four different agricultural wastes, namely corn trunks, rice husks, wild sugarcane, and soya bean sludge, were tested separately as substrates to produce lovastatin using a new fungal strain, Aspergillus sclerotiorum PSU-RSPG 178, under both submerged and solid-state fermentation (SSF).

Results and conclusions. Of these substrates and cultivation systems, soya bean sludge gave the highest lovastatin yield on dry mass basis of 0.04 mg/g after 14 days of SSF at 25 °C. Therefore, the soya bean sludge was separately supplemented with glucose, wheat flour, trace elements, palm oil, urea and molasses. The addition of the palm oil enhanced the lovastatin yield to 0.99 mg/g. In addition, the optimum conditions, which gave a lovastatin yield of (20±2) mg/g after 18 days of SSF, were soya bean sludge containing 80 % moisture (dry basis) at a ratio of soya bean sludge (g) to mycelial agar plugs of 1:4, and a ratio of soya bean sludge (g) to palm oil (mL) of 1:2. Besides, the lovastatin yields obtained from SSF using fresh or dry soya bean sludge were not significantly different.

Novelty and scientific contribution. We conclude that A. sclerotiorum PSU-RSPG 178 has a good potential as an alternative strain for producing lovastatin using soya bean sludge supplemented with palm oil as a carbon source.

https://doi.org/10.17113/ftb.58.02.20.6581

High-Throughput, Sequence-Based Analysis of the Microbiota of Greek Kefir Grains from Two Geographic Regions

Mary S. Kalamaki¹* and Apostolos S. Angelidis²

¹Division of Science & Technology, American College of Thessaloniki, 17 Sevenidi Street, 55510 Thessaloniki, Greece

²Department of Hygiene and Technology of Food of Animal Origin, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

Article history:

Received: 23 November 2019

Accepted: 8 June 2020

Key words:

kefir, bacterial diversity, species richness, high-throughput sequencing, probiotic drink

Summary:

Research background. Kefir is a natural probiotic drink traditionally produced by milk fermentation using kefir grains. Kefir grains are composed of a complex population of bacteria and yeasts embedded in a polysaccharide-protein matrix. The geographic origin of kefir grains may largely influence their microbial composition and the associated kefir drink properties. Although the detailed bacterial composition of kefir grains from several geographic regions has been reported, to date, analogous data about the microbiome of Greek kefir are lacking. Hence, the aim of this study is to investigate the structure and the diversity of the bacterial community of Greek kefir grains.

Experimental approach. The bacterial community structure and diversity of two different kefir grains from distant geographic regions in Greece were examined via high-throughput sequencing analysis, a culture-independent metagenomic approach, targeting the 16S rRNA V4 variable region, in order to gain a deeper understanding of their bacterial population diversities.

Results and conclusions. Firmicutes (a phylum that includes lactic acid bacteria) was strikingly dominant amongst the identified bacterial phyla, with over 99 % of the sequences from both kefir grains classified to this phylum. At the family level, Lactobacillaceae sequences accounted for more than 98 % of the operational taxonomic units (OTUs), followed by Ruminococcaceae, Lahnospiraceae, Bacteroidaceae and other bacterial families of lesser abundance. Α relatively small number of bacterial genera dominated, with Lactobacillus kefiranofaciens being the most abundant in both kefir grains (95.0 % of OTUs in kefir A and 96.3 % of OTUs in kefir B). However, a quite variable subdominant population was also present in both grains, including bacterial genera that have been previously associated with the gastrointestinal tract of humans and animals, some of which are believed to possess probiotic properties (Faecalibacterium spp., Bacteroides spp., Blautia spp.). Differences among the bacterial profiles of the two grains were very small indicating a high homogeneity despite the distant geographic origin.

Novelty and scientific contribution. This is the first study to deeply explore and report on the bacterial diversity and species richness of Greek kefir.