Can fermentation methods and granulometry modulate bread starch digestibility without hindering its technological quality?

Reducing starch digestibility in bread while maintaining its quality has been a trending topic in recent decades. This study explores the effects of different fermentation methods—Direct Method (DM), Poolish (PO), and Sourdough (SD)—combined with semolina of varying granulometry (Fine Semolina (FS), ~150 μm; Coarse Semolina (CS), ~550 μm) on bread properties. A full factorial design was employed to assess the influence of these variables on dough properties (pH and total titratable acidity (TTA)), bread quality (porosity, texture profile analysis, and volume), and in vitro digestibility (using Englyst’s method). Results indicate that SDfermented doughs exhibited higher TTA and lower pH, leading to bread with reduced porosity and volume compared to PO and DM, and a reduced starch digestibility due to a dense crumb structure. CS produced slightly more porous bread with lower resistant starch than FS. To conclude, the fermentation method was the major factor influencing bread quality and digestibility

Arthrospira platensis Extract: A Non-Invasive Strategy to Obtain Adjunct Attenuated Cultures

This study aims at proposing the use of Arthrospira platensis, commonly known as Spirulina, extract as a non-invasive method to attenuate the growth rate of non-starter adjunct cultures, thus preventing the over-acidification that may occur during cheese manufacturing. A preliminary screening using four different concentrations (0.20%, 0.30%, 0.50%, and 0.70%) of A. platensis extract and four starter and three non-starter lactic acid bacteria strains was performed by impedometric analysis. This allowed us to select one starter and one non-starter strain to be used in the in vitro simulation of a co-culture in milk with the best antimicrobial concentration (0.3%). The growth dynamics of the two selected strains, starter Lactococcus lactis 1426 and non-sarter Lacticaseibacillus rhamnosus 1473, co-cultured for 120 h was monitored by three different approaches: (i) plate counting on M17, for the enumeration of lactococci, and MRS for lactobacilli; (ii) fluorescence microscopic counting of viable and non-viable coccoid Lactococcus lactis 1426 and rod-shaped Lacticaseibacillus rhamnosus 1473 cells; (iii) the overall estimation of co-culture growth behavior by impedometric parameters Lag, Rate, and yEnd. All the data obtained from the in vitro simulation were in agreement, revealing that a slowdown of non-starter growth occurred, while the starter strain was not affected, or slightly stimulated, from the antimicrobial presence. In particular, the growth of Lb. rhamnosus 1473 was delayed without adversely compromise the cells’ integrity, connected with metabolic functions, showing a great potential for use in cheese production

Stabilization of Arthrospira platensis with high-pressure processing and thermal treatments: Effect on physico-chemical and microbiological quality

Arthrospira platensis (Spirulina) is a cyanobacterium that has been recently studied for food applications due to its high biological and nutritional value. When A. platensis is used as an ingredient in food applications, proper treatments have to be applied in order to reduce microbial contamination. This work compared the effect of thermal treatments (sterilization at 121℃ and pasteurization at 90℃) and high-pressure processing (400, 600 MPa) on the chemical, physico-chemical, and microbial quality of 5% (wt/vol) A. platensis aqueous suspensions. Total antioxidant capacity, total polyphenols content, color, and pigments content were not strongly lowered/modified by the high-pressure processing (HPP) treatments. HPP at 400 MPa even improved the release of C-phycocyanin from the biomass because of the breakage of cell walls. HPP treatments were comparable to pasteurization in reducing yeasts, coliforms, Staphylococci, and total bacterial count. Conversely, sterilization was the only treatment that guaranteed the inactivation of spore-forming species but affecting the final quality. Novelty impact statement: High-pressure processing (HPP) treatments were found to be a good strategy to preserve or even improve some physical and chemical properties of Arthrospira platensis (Spirulina), in particular antioxidant capacity, polyphenols, color, and pigments content. Furthermore, HPP treatments were comparable to pasteurization in reducing microbial cell count, while sterilization was the only treatment able to ensure the inhibition of spore-forming species

Phenotypic Diversity of Lactobacillus casei Group Isolates as a Selection Criterion for Use as Secondary Adjunct Starters

Autochthonous lactic acid bacteria (LAB) play a key role in the development of cheese flavor. As the pasteurization treatment on raw milk causes the elimination of LAB, secondary starter cultures are used in cheese manufacture to obtain cheeses with improved and standardized flavors. In this work, strains of the L. casei group isolated from traditional Italian cheeses were screened for their phenotypic features of technological interest for use as secondary starters. Their milk acidifying performance and the production of volatile compounds when grown in milk were evaluated. Simultaneously, the acetoin metabolic pathway presence was screened in the strains and assessed for its transcriptional activation. The results showed that the analyzed strains, despite belonging to taxonomically-related species, vary greatly according to the measured phenotypes. Four strains among the fourteen screened could be potentially used as adjunct cultures for cheese-making processes. The strain that showed the highest production of acetoin upregulated the aspartate pathway. An increased knowledge of volatile compounds’ production and acidifying properties of LAB strains isolated from traditional dairy products might guide the selection of strains for industrial applications

Lactobacillus paracasei 4341 as adjunct culture to enhance flavor in short ripened Caciotta-type cheese

Caciotta is the name used to define a type of Italian semi-hard cheese Caciotta-type cheese. Due to the short ripening time, pasteurization is necessary to eliminate the potential pathogenic bacteria, which may be present in raw milk, causing also the reduction of ripened cheese flavor. The purpose of this research was to evaluate the effect of a selected wild Lactobacillus paracasei strain experimentally used as adjunct culture to enhance the flavour formation in a short-ripened caciotta-type cheese. An integrated polyphasic approach was used to compare the experimental and control Caciotta produced in a company located in Emilia Romagna region (Italy). It was demonstrated how the L. paracasei 4341 was able to develop in curd and cheese interacting with the acidifying commercial starter. The main acidifying starter species, were differently affected by the presence of the adjunct culture. Streptococcus thermophilus shown comparable behavior in all cheese-making step of control and experimental Caciotta, while Lactobacillus delbrueckii subsp bulgaricus, growth was slowed down by the presence of the adjunct culture during the whole ripening time. The higher amount of volatile compounds and organic acids due to the adjunct L. paracasei 4341 lead to a clear differentiation of the experimental Caciotta respect to the control, in terms of aromatic profile, color, texture and sensorial perception

Study of the bacterial diversity of foods: PCR-DGGE versus LH-PCR

The present study compared two culture-independent methods, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and length-heterogeneity polymerase chain reaction (LH-PCR), for their ability to reveal food bacterial microbiota. Total microbial DNA and RNA were extracted directly from fourteen fermented and unfermented foods, and domain A of the variable regions V1 and V2 of the 16S rRNA gene was analyzed through LH-PCR and PCR-DGGE. Finally, the outline of these analyses was compared with bacterial viable counts obtained after bacterial growth on suitable selective media. For the majority of the samples, RNA-based PCR-DGGE revealed species that the DNA-based PCR-DGGE was not able to highlight. When analyzing either DNA or RNA, LH-PCR identified several lactic acid bacteria (LAB) and coagulase negative cocci (CCN) species that were not identified by PCR-DGGE. This phenomenon was particularly evident in food samples with viable loads b 5.0 Log cfu g−1 . Furthermore, LH-PCR was able to detect a higher number of peaks in the analyzed food matrices relative to species identified by PCR-DGGE. In light of these findings, it may be suggested that LH-PCR shows greater sensitivity than PCR-DGGE. However, PCR-DGGE detected some other species (LAB included) that were not detected by LH-PCR. Therefore, certain LH-PCR peaks not attributed to known species within the LH-PCR database could be solved by comparing them with species identified by PCR-DGGE. Overall, this study also showed that LH-PCR is a promising method for use in the food microbiology field, indicating the necessity to expand the LH-PCR database, which is based, up to now, mainly on LAB isolates from dairy produc

Prevalencia del patrón dactilar en los dermatoglifos de estudiantes universitarios de Jalisco, México

fingerprinting is the sci ence that allows the identification of people through the study of the impressions of the papillary ridges of the fingertips. Despite its importance, in Mexico the data published on the frequency of the fingerprint date back to 1966. The studied sample consisted of 66 women and 34 male university students of Jalisco following the classification of Juan Vucetich. The results obtained showed that the fingerprint pattern with more frequency in right thumb in men was whorl (52.9%) and in women external loop (48.5%); left thumb whorls (52.9%) in men and (54.5%) in women; men's right index the internal loop (44.1%), and women (43.9%), left index internal loop in men and women (55.9%); middle finger, right hand, in both genders external loop (88.2%) men and (77.3%) women, and in middle finger, left hand in both genders, inner loop (79.4%) men and (71.2%) women; right ring in men whorl (47.1%), women inner loop (51.5%), in left ring in both genders inner loop (55.9%) men and (56.1%) women; and on the right pinky in b oth genders external loop (85.3%) men and women (78.8%), in left pinky in both genders inner loop (97.1%) men and (84.8%) women. Comparing fingerprint by gender with X2 there were only statistically significant differences p = 0.0029 in fingerprint pattern "arc". Data not currently reported in any other study in the Mexican population

Different methodological approaches to study lactic acid bacteria traits for their potential technological application

In questo progetto di tesi di dottorato sono state studiate diverse caratteristiche dei batteri lattici, che vanno dalle proprietà acidificanti, a quelle aromatizzanti fino alla produzione di esopolisaccaridi. Grazie a differenti approcci metodologici è stato possibile approfondire le conoscenze riguardanti questi aspetti che possono avere un interessante risvolto nelle applicazioni tecnologiche.In this PhD thesis project, different characteristics of lactic bacteria (LAB) have been studied, ranging from acidifying properties to the ability to produce aroma compounds and to the production of exopolysaccharides. Thanks to the use of diverse methodological approaches it has been possible to deepen the knowledge in these aspects, which may have interesting potential technological applications