The effect of lactic acid bacteria and yeast usage on aroma development during tarhana fermentation

In Vitro Evaluation of the Technological and Probiotic Potential of Pichia kudriavzevii Strains Isolated from Traditional Fermented Foods

The isolation of endogenous yeast strains from traditionally fermented food products to use as functional starter cultures has become more popular for improved food safety, quality, and beneficial health effects. In this study, 107 Pichia kudriavzevii strains were isolated from sourdough, shalgam, tarhana, artisanal Tulum cheese, and yogurt. The strains were identified by DNA fingerprinting using iPBS-PCR method before technological and probiotic characterization. The multivariate statistical approach revealed that five strains were most promising in terms of technological characterization, including different harsh growth conditions. These strains were also examined in terms of probiotic properties with a commercial S. cerevisiae var boulardii MYA-796 strain. The multivariate statistical analyses indicated that P. kudriavzevii 5S5 were most promising in in vitro probiotic properties such as surviving in human GI conditions, adhering to intestinal cell lines, and exhibiting high hydrophobicity. Therefore, it seems to be a great starter candidate for the production of functional fermented food products.

The Combined Effect of Lactic Acid Bacteria and Galactomyces geotrichum Fermentation on the Aroma Composition of Sour Whey

The increase in demand for food flavorings due to the shortening and simplification of food production technology also entails an increase in the demand for new technologies for their production. The biotechnological production of aromas is a solution characterized by a high efficiency, an independence from environmental factors and a relatively low cost. In this study, the influence of the implementation of lactic acid bacteria pre-fermentation into the production of aroma compounds by Galactomyces geotrichum on a sour whey medium on the intensity of the obtained aroma composition was analyzed. The monitoring of the culture in terms of biomass buildup, the concentration of selected compounds, and the pH resulted in the confirmation of interactions between the analyzed microorganisms. The post-fermentation product underwent a comprehensive sensomic analysis for the identification and quantification of the aroma-active compounds. The use of gas chromatography-olfactometry (GC-O) analysis and the calculation of odor activity values (OAVs) allowed 12 key odorants to be identified in the post-fermentation product. The highest OAV was found for phenylacetaldehyde with a honey odor (1815). The following compounds with the highest OAVs were 2,3-butanedione with a buttery aroma (233), phenylacetic acid with a honey aroma (197), 2,3-butanediol with a buttery aroma (103), 2-phenylethanol with a rosy aroma (39), ethyl octanoate with a fruity aroma (15), and ethyl hexanoate with a fruity aroma (14).

Fermented cereal soup with artichoke (Cynara scolymus L.) bracts: volatile profile, functional, powder and sensory properties

BACKGROUND

Artichoke (Cynara scolymus L.) bracts are agricultural wastes formed during artichoke processing. Artichoke bracts are used in fermented cereal soup tarhana to replace 10%, 20%, and 30% of wheat flour and functional, powder, sensory properties and volatile compounds of tarhana samples were investigated.

RESULTS

The use of artichoke bracts in tarhana increased total (8.37-17.17 g/100 g) and insoluble dietary fiber (5.84-14.09 g/100 g), total phenolic content (2.88-3.62 mg GAE/g), and antioxidant activity (3.07-3.86 μmol TE/g) values. Replacement of wheat flour by artichoke bracts resulted in lower L*, a*, and b* values. While water absorption capacity increased, oil absorption capacity and emulsifying activity were not affected by artichoke bracts replacement. Artichoke bracts replacement in tarhana influenced powder characteristics as, decrease in bulk density, increase in Carr index, wettability, and dispersibility values. Volatiles from terpene are most abundant (64.47-27.17 mg/kg) in tarhana containing artichoke bracts, followed by volatiles from ester (42.91-25.85 mg/kg). Limonene was the main volatile compound of tarhana samples.

CONCLUSION

Sensory acceptable tarhana was obtained when up to 30% artichoke bracts were used as wheat flour replacer in tarhana. The contribution to sustainability was achieved, and a healthier tarhana rich in dietary fiber was obtained by using artichoke bracts in tarhana. © 2023 Society of Chemical Industry.

A multi-functional survey of the properties of Lacticaseibacillus paracasei subsp. tolerans NOC-122, Levilactobacillus parabrevis NOC-111 and Latilactobacillus curvatus NOC-110

This study aimed to reveal the physicochemical and organoleptic effects of three functional lactic acid bacteria (LAB) isolates in a milk medium: Lacticaseibacillus paracasei subsp. tolerans NOC-122, Levilactobacillus parabrevis NOC-111 and Latilactobacillus curvatus NOC-110. A total of 200 indigenous LAB strains isolated from artisanal tulum cheeses were screened for potential proteolytic and lipolytic activity, citrate-lyase-synthesizing and exopolysaccharide-producing ability. Furthermore, a total of six fermented products were produced using these strains as a single culture or as a co-culture. The physicochemical and microbiological properties, angiotensin-converting-enzyme (ACE) inhibitor activity, and the amino acid and volatile aroma compound profiles were determined. According to the results, NOC-110 and NOC-122 were effective in increasing ACE-inhibitory activity. On the other hand, NOC-122 was responsible for a fresh cheesy, slightly oily flavour when used as a single culture. NOC-111 gave a fresh, fruity and slightly herbal flavour; NOC-110 gave a flavour similar to that of NOC-122 when they were used as a single culture. Also, co-cultures of the strains were investigated. The results of the study provide a guide to the usability of these isolates as single or co-cultures in the production of dairy-based food. These findings can be of value for many future studies and innovative food products.

Protein Sources Alternative to Meat: State of the Art and Involvement of Fermentation

Meat represents an important protein source, even in developing countries, but its production is scarcely sustainable, and its excessive consumption poses health issues. An increasing number of Western consumers would replace, at least partially, meat with alternative protein sources. This review aims at: (i) depicting nutritional, functional, sensory traits, and critical issues of single-cell proteins (SCP), filamentous fungi, microalgae, vegetables (alone or mixed with milk), and insects and (ii) displaying how fermentation could improve their quality, to facilitate their use as food items/ingredients/supplements. Production of SCP (yeasts, filamentous fungi, microalgae) does not need arable land and potable water and can run continuously, also using wastes and byproducts. Some filamentous fungi are also consumed as edible mushrooms, and others are involved in the fermentation of traditional vegetable-based foods. Cereals, pseudocereals, and legumes may be combined to offer an almost complete amino acid profile. Fermentation of such vegetables, even in combination with milk-based products (e.g., tarhana), could increase nutrient concentrations, including essential amino acids, and improve sensory traits. Different insects could be used, as such or, to increase their acceptability, as ingredient of foods (e.g., pasta). However, insects as a protein source face with safety concerns, cultural constraints, and a lack of international regulatory framework.

Bioconversion of Apple Pomace into Microbial Protein Feed Based on Extrusion Pretreatment

Apple pomace (AP) is often used directly as animal feed, while the value of feeding is limited by its low protein content. In this study, extrusion pretreatment was performed for AP, and further fermentation was carried out to improve its nutrition value. Strains suitable for extruded apple pomace (EAP) to produce high-quality microbial protein (MP) feed were screened from 12 different strains. Results showed that Aspergillus niger 3.324 (Asn), Candida utilis1314 (Cau), Geotrichum candidum 1315 (Gec), Bacillus subtilis A308 (Bas1), and Lactic acid bacteria (Lac) were screened as the dominant strains, which exhibited higher feeding value. Strong symbiotic effect was observed in fermentation with mixed strains of Asn, Cau, Gec, and Lac at the ratio of 1:1:1:1. Compared with AP, the pure protein content in the optimized fermented EAP (FEAP) was increased by 138% accompanying with a pleasant flavor and taste. And its pure protein content was increased by 19.20% in comparison to that of the fermented apple pomace. The nutrition value of FEAP was characterized by amino acid profiles; it found that FEAP was comparable to other commercial proteins with higher contents of histidine, phenylalanine, threonine, and valine. Combination of fermentation and extrusion technology significantly enhanced pure protein content and nutritional composition of apple pomace, which was revalorized as a nutritive animal feed rich in microbial protein.

Production and characterization of yeast extracts produced by Saccharomyces cerevisiae, Saccharomyces boulardii and Kluyveromyces marxianus

In recent years, prejudice in society against monosodium glutamate (MSG) has directed food manufacturers to alternative sources. Yeast extracts are considered as "natural" due to the production process and stand out due to their nutritional properties as well as giving a flavor similar to MSG. In this study, chemical, functional and flavor properties of yeast extract powders produced from Saccharomyces cerevisiae TGM10, Saccharomyces boulardii S11 and Kluyveromyces marxianus TGM66 were evaluated. Results revealed that the most protein-rich sample was S. cerevisiae TGM10 extract (69.17%), followed by S. boulardii S11 (66.16%) and K. marxianus TGM66 (62.42%) extracts, respectively and S. cerevisiae TGM10 extract was also the richest yeast extract for essential amino acids. Additionally, flavor-enhancing amino acids such as glutamic acid, aspartic acid, alanine and glycine were dominant in S. cerevisiae TGM10 extract (47.41 g/100 g protein). Sensorial evaluation of yeast extracts demonstrated that salty taste, umami taste and meaty flavor scores of yeast extracts were lower than MSG whereas for fruity flavor, yeast extracts had the highest scores. These findings revealed the potential of three yeast strains to produce yeast extracts in order to increase the nutritional value and flavor of foods.