Use of a lactic acid bacteria starter culture during green olive (Olea europaea L cv Ascolana tenera) processing

Among the Italian olive germplasm, ‘Ascolana tenera’ is one of the best varieties for table olive production. This research addressed the impact of different processing types (Greek‐style and Spanish‐style) on the fermentation and phenolic composition of olive fruit. In particular, the effects of a lactic acid bacteria (LAB) starter culture on the fermentation of naturally green olives processed according to the traditional Greek method were studied. Results revealed that Spanish‐style processing produced a dramatic loss of total phenolics, while natural olive processing favoured a higher retention of biophenols. Oleoside 11‐methylester, a phenol‐related compound, and hydroxytyrosol, tyrosol, vanillic acid, 3,4‐dihydroxyphenylglycol, oleuropein and oleuropein aglycons, as the main phenols, were detected in olive fruit. More interestingly, this research indicated that inoculation with LAB affected the pH, total acidity, microbial profile and palatability of olives. Olives fermented with the LAB starter culture were perceived by panellists to be less bitter and more aromatic than those spontaneously fermented. Thus the use of LAB inoculants during olive fermentation could be applied with the currently available technology. Copyright © 2005 Society of Chemical Industry     

Selection of Lactobacillus plantarum strains to use as starters in fermented table olives: Oleuropeinase activity and phage sensitivity

Fermented table olives (Olea europaea L.) are largely diffused in the Mediterranean area. Olives are picked at different stages of maturity and after harvesting, processed to eliminate the characteristic bitterness caused by the presence of the oleuropein glucoside and to become suitable for human consumption. The spontaneous fermentation of table olives mainly depends on lactic acid bacteria (LAB), and in particular on Lactobacillus plantarum which plays an important role in the degradation of oleuropein. The hydrolysis of oleuropein is attributed to the β-glucosidase and esterase activities of the indigenous LAB microflora. This study investigated the potential of L. plantarum strains isolated from dairy products and olives to be used as starters for fermented table olives. Forty-nine strains were typed by RAPD-PCR and investigated for the presence of the β-glucosidase (bglH) gene. The full sequence of the bglH gene was carried out. All the 49 L. plantarum strains were also tested for phage resistance. A total of six strains were selected on the basis of genotypic polymorphism, bglH gene sequence analysis, and phage resistance profile. These strains were further characterized to assess the acidifying capability, the growth at different temperatures, the tolerance to different NaCl concentrations, and the oleuropeinolytic activity. Although further characterizations are required, especially concerning the influence on sensory properties, L. plantarum proved to have the potential to be used as a debittering and fermentative agent in starter culture for fermented table olives.     

Effect of kaolin and copper based products and of starter cultures on green table olive fermentation

In the present study table olives treated in field with kaolin and copper based products against “olive-fruit fly” were fermented using two selected strains of lactic acid bacteria (LAB). The fermentation process was monitored up to 260 days from brining through physico-chemical, microbiological and sensorial analyses. Results showed a dominance of LAB and yeasts and low level of Enterobacteriaceae counts throughout the whole process both in un-treated and treated samples. When investigating the effect of the single treatments on microbial dynamics, ANOVA results highlighted that copper based products affected significantly the control sample, while the sample inoculated with LAB starters maintained high level throughout the process, guaranteeing the fermentation process. Different behavior was revealed by yeasts population, which was partially influenced by copper treatment at the beginning of the fermentation.The polyphasic approach used in the present study, which combined sensory evaluation to microbial counts and physico-chemical characteristics, let to the conclusion on the importance of starter cultures in fermentation of table olives especially those treated with “non-conventional” pesticide, which could be used to prevent olive fly damage.     

Evaluation of a single and combined inoculation of a Lactobacillus pentosus starter for processing cv. Arbequina natural green olives

The production of Arbequina naturally green olives is a traditional and spontaneous process in which lactic acid bacteria (LAB) and yeasts are present. To better control the fermentation of olives, strains of LAB and yeasts that had been isolated from brines were used in this study.     

发酵肉制品中高抗氧化肉品发酵剂的筛选鉴定

为获得高抗氧化活性的天然肉品发酵剂,通过清除自由基、还原能力和抗脂质过氧化实验对来源于5种发酵肉制品中30株乳酸菌的发酵上清液、菌体细胞和胞内提取物的抗氧化活性进行研究,并按照肉品发酵剂的筛选标准对高抗氧化性的菌株进行筛选,鉴定出符合要求的菌株。结果表明:这30株乳酸菌具有不同的抗氧化能力且不同组分的抗氧化活性之间存在很大差异,发现菌株L23、L26和L28具有较高的抗氧化活性,其中L23符合肉品发酵剂的筛选标准,可作为天然高抗氧化性肉品发酵剂用于生产。经鉴定L23为希腊魏斯氏菌。     

Diversity of bacterial population of table olives assessed by PCR-DGGE analysis

Nocellara Etnea and Geracese table olives are produced according to traditional process, in which lactic acid bacteria (LAB) and yeasts are the dominant microorganisms. With the aim to evaluate the effect of selected starter cultures on dynamics of bacterial population during fermentation and on growth/survival of Listeria spp. artificially inoculated into the olive brine, a polyphasic approach based on the combination of culturing and PCR-DGGE analysis was applied. Plating results showed a different concentration of the major bacterial groups considered among cultivars and the beneficial effect of LAB starters, which clearly inhibited Enterobacteriaceae. Moreover, results indicated that the brine conditions applied did not support the growth/survival of Listeria monocytogenes strain, artificially inoculated, highlighting the importance of selecting right fermentation parameters for assuring microbiological safety of the final products. Comparison of DGGE profile of Nocellara Etnea and Geracese table olives, displayed a great difference among cultivars, revealing a wide biodiversity within Lactobacillus population during Geracese olives fermentation. Based on cloning and sequencing of the most dominant amplicons, the presence, among others, of Lactobacillus paracollinoides and Lactobacillus coryniformis in Geracese table olives was revealed in table olives for the first time.     

Culture-independent study of the diversity of microbial populations in brines during fermentation of naturally-fermented Aloreña green table olives

Aloreña table olives are naturally fermented traditional green olives with a denomination of protection (DOP). The present study focused on Aloreña table olives manufactured by small and medium enterprises (SMEs) from Valle del Guadalhorce (Southern Spain) under three different conditions (cold storage, and ambient temperature fermentations in small vats and in large fermentation tanks). The microbial load of brines during fermentation was studied by plate counting, and the microbial diversity was determined by a culture-independent approach based on PCR-DGGE analysis. The viable microbial populations (total mesophilic counts, yeasts and molds, and lactic acid bacteria — LAB) changed in cell numbers during the course of fermentation. Great differences were also observed between cold, vat and tank fermentations and also from one SME to another. Yeasts seemed to be the predominant populations in cold-fermented olives, while LAB counts increased towards the end of vat and tank fermentations at ambient temperature. According to PCR-DGGE analysis, microbial populations in cold-fermented olives were composed mostly by Gordonia sp./Pseudomonas sp. and Sphingomonas sp./Sphingobium sp./Sphingopyxis sp. together with halophilic archaea (mainly by haloarchaeon/Halosarcina pallida and uncultured archaeon/uncultured haloarchaeon/Halorubrum orientalis) and yeasts (Saccharomyces cerevisiae and Candida cf. apicola). Vat-fermented olives stored at ambient temperature included a more diverse bacterial population: Gordonia sp./Pseudomonas sp., Sphingomonas sp./Sphingobium sp./Sphingopyxis sp. and Thalassomonas agarivorans together with halophilic archaea and yeasts (mainly S. cerevisiae and C. cf. apicola, but also Pichia sp., and Pichia manshurica/Pichia galeiformis). Some LAB were detected towards the end of vat fermentations, including Lactobacillus pentosus/Lactobacillus plantarum and Lactobacillus vaccinostercus/Lactobacillus suebicus. Only the tank fermentation showed a clear predominance of LAB populations (Lactobacillus sp., Lactobacillus paracollinoides, and Pediococcus sp.) together with some halophilic archaea and a more selected yeast population (P. manshurica/P. galeiformis). The present study illustrates the complexity of the microbial populations in naturally-fermented Aloreña table olives.     

乳酸菌抗氧化活性及其在发酵肉制品中的应用研究进展

乳酸菌作为发酵肉制品中的发酵剂,已被证实具有抗氧化活性,但在发酵过程中,容易受到各种环境胁迫因子的影响,这些胁迫因子能够诱发菌体胞内活性氧自由基的产生和积累,进一步影响菌株的抗氧化活性,很大程度上限制了其在发酵肉制品中的抗氧化作用。本文综述乳酸菌面临的环境胁迫因子,探究其对氧化胁迫的应答与防御机制和抗氧化机理,并阐述提升乳酸菌氧化胁迫抗性的策略及乳酸菌在发酵肉制品中的抗氧化作用。     

Effects of alkali neutralization with CO2 on fermentation, chemical parameters and sensory characteristics in Spanish-style green olives (Olea europaea L.)

This paper aimed to study CO₂ use as alkali neutralizing agent instead of the traditional washings with water, in Spanish-style green olives. Titratable acidity, pH, sugars and microbial populations were monitored during processing. CO₂ treatment was effective in reducing water-soluble carbohydrate loss from the olives during washing step and affected combined acidity and lactic acid fermentation. The final pH of the fermented brine was higher than in control, mainly due to high buffering capacity of the solution. CO₂ treatment allowed the reduction of more than 80% of the wastewaters. Sensory evaluations of the end product were carried out. Olives treated with CO₂ were perceived to be more intense in acidic taste than control, while for texture attributes no differences were detected.     

Vapor Analysis of Fermented Spanish-type Green Olives by Gas Chromatography

SUMMARY: Five major components were detected gas chromatographically in the head-space vapor (HSV) of Spanish-type green olives fermented by pure cultures of Lactobacillus plantarum, Pediococcus cerevisiae and Leuconostoc mesenteroides. Three of these compounds were identified as acetaldehyde, methyl sulfide, and ethanol. The same compounds were present in unfermented olives but in different amounts. Olives that had undergone a natural fermentation contained the above five compounds, and, in addition, a varying number of other compounds. These results indicated that HSV analysis may be a rapid method for detecting volatile end products resulting from the metabolism of various microorganisms. A high ethanol content was found in olive brines that contained a predominance of yeasts. Abnormal fermentations gave unique HSV profiles, one of which indicated a high level of 2-butanol. Methyl sulfide was found to be a major odor component of fermented as well as unfermented olives. Acetaldehyde and ethanol contributed secondarily to the odor. Primary contributions of fermentation by the above lactic acid bacteria to the flavor of olives were: (1) production of a desirable level of acidity, and (2) utilization of fermentable sugars to the exclusion of microorganisms which produce metabolic end products with undesirable flavor characteristics.     

酵母与乳酸菌的相互作用模式及其在发酵食品中的应用研究进展

酵母与乳酸菌作为被广泛应用的微生物在发酵食品的生产过程中起着举足轻重的作用,二者在发酵体系中的作用方式直接决定了产品的品质。研究发酵体系中酵母-乳酸菌间的相互作用模式有助于揭示微生物与食品功能的关系,对发酵进程的正向调控具有重要意义。本文综述了酵母与乳酸菌在发酵过程中发生的协同/拮抗作用、营养代谢产物交换、群体感应及生物膜包被等相互作用模式,探讨了酵母-乳酸菌相互作用对改善发酵食品风味质构、缩短发酵周期、提升产品益生特性等的积极作用。最后,对酵母-乳酸菌作为组合发酵剂进行强化发酵的应用前景进行了总结与展望。     

产乳化活性多糖乳酸菌的筛选及其发酵荞麦酸面团、面包的特性

本研究从不同来源的原料中分离得到18株具有产胞外多糖(EPS)能力的乳酸菌,通过对比发酵液及乳酸菌荞麦酸面团的乳化活性,获得一株产EPS且乳化活性较高的乳酸菌,并应用于荞麦酸面团的制作。采用动态流变测定、激光共聚焦观察、质构分析等手段,研究其对荞麦酸面团面包烘焙学特性的影响。结果表明:优选产乳化性多糖的乳酸菌YC'-22经鉴定为发酵乳杆菌(Lactobacillus fermentum strain HBUAS54017),且同源性为100%,EPS产量为1.63 g/L。通过添加乳酸菌荞麦酸面团,使面包面团的面筋网络结构得到强化。相比空白面包(CB),添加1.0%阿拉伯胶的荞麦面包(AGB)、荞麦酸面团面包(SDB)的比容分别增加了12.42%和14.08%,硬度分别降低了13.90%和22.87%;其中SDB面包整体可接受度最高,改善效果最明显。因此,产乳化性多糖的乳酸菌发酵的荞麦酸面团可以作为一种天然的面包功能配料。     

海藻乳酸菌发酵的研究进展

海藻是一类重要的海洋资源,富含大量营养元素如蛋白质、碳水化合物、维生素和矿物质,以及多糖、酚类等生物活性物质。由于海藻营养价值极高,利用乳酸菌发酵海藻促进生物活性化合物的产生和释放,具有良好的健康效益。因此,本文根据国内外近年来利用乳酸菌发酵海藻的相关研究报道,对乳酸菌发酵类型、乳酸菌发酵海藻的可行性和乳酸菌主要种类、以及乳酸菌在海藻发酵中的效果和作用进行阐述,同时综述了乳酸菌发酵海藻在食品行业中的开发应用现状,并对今后发展趋势和前景进行展望,为藻类乳酸菌发酵制品的开发提供一定参考。     

Species diversity and metabolic impact of the microbiota are low in spontaneously acidified Belgian sausages with an added starter culture of Staphylococcus carnosus

Quality of fermented sausages is affected by acidifying lactic acid bacteria (LAB) and colour- and flavour-promoting coagulase-negative staphylococci (CNS), whether or not used as starter culture. Artisan fermented sausages are often perceived as superior to industrial variants, partially because of the specific microbiota due to spontaneous acidification, which may be considered as an artisan characteristic. Therefore, two kinds of spontaneously acidified Belgian sausages were prepared (Belgian-type salami and Boulogne sausage), but with addition of a Staphylococcus carnosus culture. The Belgian-type salami was made from pork and beef, whereas the Boulogne sausage contained pork and horse meat. In all cases, Lactobacillus sakei was the dominant LAB species present on the raw materials and during fermentation, whereas enterococci remained present in the background. Enterobacteriaceae vanished after fermentation. The CNS species diversity on the raw materials was large and differed between the pork, beef, and horse meat. Nevertheless, this species diversity was annihilated during fermentation by the added S. carnosus culture. The volatiles fraction was mainly composed of aldehydes that originated from lipid oxidation and spices-derived compounds. Aromatic compounds that are typically associated to CNS activity, such as end-products from the metabolism of branched-chain amino acids, were not present in the Belgian-type salami and only marginally present in the Boulogne sausage. In conclusion, spontaneous acidification of Belgian-type fermented sausages leads to dominance of L. sakei and is no guarantee for bacterial contribution to the aroma profile when S. carnosus is added as a starter culture.     

Characterization of flavour and volatile compounds of fermented squid using electronic nose and HPMS in combination with GC-MS

The present study investigated the flavour characteristics and key volatile components of fermented squid (Dosidicus gigas) as well as their formation mechanism by three different starter cultures of lactic acid bacteria (LAB) and natural squid. The sensory assessment, volatile compounds, as well as the amino acids of the mixed fermented squid were detected using pickled brine as samples of fermented squid. A total 88 types of volatile compounds were found in four samples by 0–72 h of fermentation. After fermentation by LAB, the volatile compounds of squid showed that the fermented squid with different started cultures differed mainly in terms of numbers of alcohols, ketones, and esters. Furthermore, the amounts of volatile compounds among three starter cultures were also obviously different. Gas Chromatography-Mass Spectrometer (GC-MS) analysis indicated that the mixed fermentation process contained relatively higher (+)-limonene (11.71%) (lemon scent) and 3-hydroxy-2-butanone (5.72%) (creamy taste). These compounds were not detected in the control group. The main flavour compounds of nonanal and 2, 4-decadienal were gradually reduced. Meanwhile, 2, 3-butanedione, 2-heptanone, 2-pentylfuran, and nonanoic acid are the key flavour components. The total principal component is 94.01%, which were clarified by electronic nose in combination with principal components analysis. After mixed fermentation by LAB, the total amino acid (TAA) content reached 85.36 g/100 g, which was almost twice the amount of the control, especially in aspartate, glutamate, and threonine. Our results indicated that LAB has obvious effects on deodorization and flavour promotion during the fermentation of squid. This study provided an important basis for the further development and utilization of squid.     

Production of Bioactive Peptides from Lactic Acid Bacteria: A Sustainable Approach for Healthier Foods

Traditional fermented foods where lactic acid bacteria (LAB) are present have been associated with beneficial effects on human health, and some of those benefits are related to protein‐derived products. Peptides produced by LAB have attracted the interest of food industries because of their diverse applications. These peptides include ribosomally produced (bacteriocins) and protein hydrolysates by‐products (bioactive peptides), which can participate as natural preservatives and nutraceuticals, respectively. It is essential to understand the biochemical pathways and the effect of growth conditions for the production of bioactive peptides and bacteriocins by LAB, in order to suggest strategies for optimization. LAB is an important food‐grade expression system that can be used in the simultaneous production of peptide‐based products for the food, animal, cosmetic, and pharmaceutical industries. This review describes the multifunctional proteinaceous compounds generated by LAB metabolism and discusses a strategy to use a single‐step production process, using an alternative protein‐based media. This strategy will provide economic advantages in fermentation processes and will also provide an environmental alternative to industrial waste valorization. New technologies that can be used to improve production and bioactivity of LAB‐derived peptides are also analyzed.     

Microbiological and physicochemical characterisation of green table olives of Halkidiki and Conservolea varieties processed by the Spanish method on industrial scale

The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties.     

Effects of indigenous starter cultures on the microbial and physicochemical characteristics of Urutan, a Balinese fermented sausage

Urutan is a Balinese traditional dry fermented sausage prepared from lean pork and various kinds of spice. Urutan is different from the European sausages, because it is fermented under warm condition with fluctuating temperatures of approximately 25 degrees C at night to 50 degrees C during sun drying. In this study, two of the 71 strains of lactic acid bacteria (LAB) isolated from natural urutan fermentation were used as starter cultures: Lactobacillus plantarum U201, the dominant LAB, and Pediococcus acidilactici U318, a bacteriocin producer. A soft urutan with yellowish brown color was produced using these strains as multiple starters. The starter cultures grew in characteristic succession which reconstructed the natural fermentation process. Lactobacilli were dominant until 48 h fermentation and pediococci dominated at the later stage of fermentation. Proliferation of starter cultures produced lactic acid which resulted in the decrease in pH and coagulation of soluble protein in urutan. Both strains could eliminate the Enterobacteriaceae in urutan after 24 h fermentation, and could suppress and eliminate the occurrence of micrococci at 120 h fermentation. By using a single starter culture, no succession was observed to occur in urutan and the time of elimination of Enterobacteriaceae was delayed. Thus, the strains of L. plantarum U201 and P. acidilactici U318 have great potential for use as multiple starter cultures in urutan fermentation.     

The effect of lactic acid bacteria fermentation on the antioxidant activity of wheat gluten pancreatin hydrolysates

The antioxidant activities of the fermented wheat gluten hydrolysates with different fermentation times were investigated to elucidate the impact of lactic acid bacteria (LAB) fermentation on the wheat gluten hydrolysates. Prior to LAB fermentation, wheat gluten was deamidated by hydrochloric acid and then hydrolysed by pancreatin to 12 and 24 h, respectively. Results showed that LAB fermentation had significant impacts on the enzymatic efficiency and antioxidant activities of wheat gluten. The degree of hydrolysis and protein recovery of hydrolysates gradually increased and then reached maximum values, respectively, when fermenting with LAB for 36 h. The hydrolysis degree and protein recovery of fermented pancreatin 24‐h hydrolysates were larger than that of the fermented pancreatin 12‐h hydrolysates during the whole fermentation. The antioxidant activity analysis revealed a marked increase and improvement in the scavenging activities of 1,1‐Diphenyl‐2‐picrylhydrazyl·radicals, hydroxyl radicals and oxygen radical absorbance capacity, while the scavenging activities of ABTS⁺ radical decreased as the fermentation time extended. The antioxidant activities of pancreatin 24‐h hydrolysates were higher than that of the pancreatin 12‐h hydrolysates during the whole LAB fermentation.     

Lactic acid fermentation as a tool for increasing the folate content of foods

Folate is an essential micronutrient involved in numerous vital biological reactions. The dietary consumption of naturally occurring vitamin B9 is often inadequate in many countries, and supplementation or fortification programs (using synthetic folic acid) are implemented to alleviate folate deficiency. Other food-based alternatives are possible, such as the use of lactic acid bacteria (LAB) to synthesize folate during fermentation. Many studies have been conducted on this topic, and promising results were reported for some fermented dairy products. However, in other studies, folate consumption by LAB or rather low folate production were observed, resulting in fermented foods that may not significantly contribute to the recommended B9 intake. In addition, the optimum conditions for folate biosynthesis by LAB are still not clear. The aim of this review was thus to (i) clarify the ability of LAB to produce folate in food products, (ii) check if the production of folate by LAB in various fermented foods is sufficient to meet human vitamin B9 requirements and (iii) suggest ways to optimize folate production by LAB in fermented food products.