Substitution Of NaCl Research Articles

Partial substitution of NaCl with chloride salt mixtures: Impact on oxidative characteristics of meat myofibrillar protein and their rheological properties

The effects of partial substitution of NaCl using chloride salt (KCl, MgCl2, and CaCl2) mixtures with different formulas on oxidative characteristics, physicochemical and gel properties of the pork meat myofibrillar protein (MP) were investigated. In a hydroxyl-radical-induced oxidative system, the mixtures of NaCl, KCl, and MgCl2 increased the carbonyl content of MP in substitution degree of 25% and 50%; and all chloride salts mixtures raised MP's disulfide bond level. In addition, chloride salt mixtures significantly lower MP gel's storage modulus, water-holding capacity, and gel strength, especially at the substituted ratio of 50%, due to the more disorderly and aggregated structure were observed in MP gels. The MP gel containing 0.45 M NaCl, 0.075 KCl, and 0.025 M MgCl2 exhibited superior qualities due to its compact pore structure. Thus, that NaCl was partially substituted by KCl and MgCl2 at a lower substituted ratio (25%) is promising to improve the functional properties of low-sodium MP gel products.

Combined Effects of Salt-related Variables on Qualitative Characteristics of Probiotic Fermented Milk

<P>Background: Doogh is a typical Iranian beverage based on fermented milk. The common salt used for Doogh is NaCl. Addition of salt in Doogh can take place before or after fermentation. The type of salt (NaCl or NaCl/KCl) and the sequence of salt addition in Doogh production can have significant impacts on biochemical characteristics of this product. </P><P> Methods: Nine probiotic Doogh treatments containing two probiotics (Lactobacillus acidophilus and Bifidobacterium lactis BB at the level of 107 cfu.mL-1) along with Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus, different salt percentages (0.5 and/or 1% (w/w)) in two ratios of NaCl/KCl (100:0 or 50:50) were prepared. Four samples were produced with the addition of salt before fermentation and four samples after fermentation (after cooling to 5°C). Apparent viscosity, phase separation, viability of probiotics and sensory properties of Doogh samples were studied during 21 days storage. </P><P> Results: The results showed that samples containing 1% (w/w) salt (NaCl or NaCl:KCl) had higher phase separation than treatments with 0.5% (w/w). The partial substitution of NaCl with KCl had a positive influence on the viability of probiotics. Treatments with 1% (w/w) NaCl:KCl and 0.5% (w/w) NaCl:KCl added before fermentation showed the maximum viability of probiotics. Addition of salt decreased the apparent viscosity of Doogh due to decreasing mean particle size of the dispersion system. From sensory point of view, the treatment with 0.5% (w/w) NaCl and those with 0.5% (w/w) NaCl:KCl before fermentation showed the highest acceptance. </P><P> Conclusion: A low-sodium Doogh with an acceptable probiotic viability was produced.</P>

New alternative to reduce sodium chloride in meat products: Sensory and microbiological evaluation

In this research, the effect of partial replacement of NaCl by Soda-Lo® salt microspheres (25% (W/W), 30% (W/W), and 50% (W/W)) on the sensory and microbiological properties of meat products such as cooked ham, turkey breast and Deli type sausages were evaluated. Content of sodium from these meat products was determined through atomic-flame emission spectroscopy. New formulations of these meat products were evaluated by a sensory trained panel, as well as studied microbiologically (shelf-life and pathogens). Significant reductions of sodium in these meat products were obtained when 50% (W/W) of NaCl was substituted by Soda-Lo®. Sodium reductions of 30.07% (W/W), 21.93% (W/W) and 10% (W/W) in cooked Deli type sausages, ham and turkey breast, respectively, in comparison with controls. Statistically differences significant (p < 0.05) among controls and replaced samples were not detected by trained sensory panelists. Statistically significant differences (p < 0.05) on the behavior of the native microflora and Salmonella Enteritidis, Staphylococcus aureus and Listeria monocytogenes in control and replaced samples for the different meat products were not found. Therefore, it is concluded that partial substitution of NaCl by Soda-Lo® in meat products could be a good alternative to reduce sodium concentrations and offer benefices to the health of consumers.

Impact of partial substitution of NaCl by KCl, and MgCl2 on physicochemical and sensory properties of cooked sausages during storage.

ObjectiveTo determine the effect of three salting treatments (control, 100% NaCl; T1, 60% NaCl and 40% KCl; T2, 50% NaCl, 40% KCl, and 10% MgCl2) on meat quality of sausages during storage.MethodsVarious types of curing salts were used for processing of salamis. Physico-chemical and sensory evaluation of the sausages were analyzed during 4 weeks of ripening.ResultsThe pH values and salinity contents were the highest in control, while they were the lowest in T2 at 4 weeks (p<0.05). Control and T1 had less thiobarbituric acid reactive substances than T2 at 2 weeks (p<0.05). The volatile basic nitrogen levels in T1 were similar to control and lower than T2 at 2 and 4 weeks (p<0.05). Moreover, T1 samples were redder and had a higher saturation index (C*) value when compared to the others. T2 showed greater hardness, gumminess and chewiness when compared with the control (p<0.05). Control was comparable to T1 for sensory attributes.ConclusionSodium chloride may be partially substituted with potassium chloride without negatively influencing meat quality of sausages up to 4 weeks of storage. These results could help to develop low-sodium sausages.

Hydrolysis and oxidation of protein and lipids in dry-salted grass carp (Ctenopharyngodon idella) as affected by partial substitution of NaCl with KCl and amino acids.

To obtain healthier meat products with reduced Na content, the salt substitute containing l-histidine and l-lysine was compared with NaCl in the hydrolysis and oxidation of protein and lipids of dry-salted fish during processing. Compared with NaCl-treated fish (S-F), salt substitute treated fish (SS-F) had a lower Na content, higher moisture content and lower hardness. Sensory analysis showed that salt substitute didn't affect the acceptability of salted fish. The free fatty acids of SS-F treated fish had a slight tendency toward lipolysis at the end of processing. Additionally, the conjugated diene value, lipoxygenase activity and malondialdehyde value were lower in the ventral and dorsal muscles for the SS-F treatment. Meanwhile, the protein carbonyls and thiol groups were significantly decreased as cathepsin B and L activities and FAA content were increased in the ventral and dorsal muscles for the SS-F treatment. l-Histidine and l-lysine accelerated the hydrolysis (inhibit the oxidation) of protein and lipids in dry-salted grass carp, illustrating that l-histidine and l-lysine will be a positive approach to develop healthier meat products.

Calcium lactate as an attractive compound to partly replace salt in blue-veined cheese

In addition to their high sodium content, cheeses are thought to induce an acid load to the body, which is associated with deleterious effects on consumers' health. Our objective was to explore the use of alkalinizing salts in partial substitution of NaCl to reduce both the sodium content and the acid-forming potential of cheese, without altering its sensory properties. Blue-veined cheeses were produced under industrial conditions, using brine salting followed by dry salting with a 4:1 (wt/wt) mixture of calcium lactate:NaCl or calcium citrate:NaCl. Sodium chloride was used in 2 granulometries: coarse (control treatment) and fine, to obtain homogeneous mixtures with the organic salts. Cheeses were then ripened for 56 d. No major appearance defects were observed during ripening. Calcium lactate substitution decreased the Na content of the cheese core by 33%, and calcium citrate substitution increased the citrate content of the cheese core by 410%, respectively, compared with fine NaCl. This study highlighted the substantial role of salt granulometry in sodium content, with the use of the coarse salt reducing the sodium content by 21% compared with fine salt. Sensory profiles showed nonsignificant differences in bitter and salty perceptions of salt-substituted cheeses with calcium lactate and calcium citrate compared with control cheeses. The use of calcium lactate should be considered to reduce the sodium content and improve the nutritional quality of cheeses while maintaining the sensory quality of the products. Alkalinizing organic salts could replace the acidifying salts KCl or CaCl2, which are currently used in salt replacement and are not recommended for consumers with renal disease. The method described here should be considered by cheese-making producers to improve the nutritional quality of cheese. Additional nutritional optimization strategies are suggested.

Manufacture of reduced-sodium Coalho cheese by partial replacement of NaCl with KCl

The effect of the partial substitution of NaCl by KCl in the following proportions 100:0; 70:30; 50:50; and 30:70 (NaCl:KCl) on the characteristics of Coalho cheese was investigated over 60 days of refrigerated storage. Partial sodium replacement did not affect the physicochemical characteristics, pH, proteolysis indices, water activity, and melting behaviour of cheeses; however, proteolysis, hardness and chewiness were significantly affected by the storage time. There was no significant difference in the counts of coliforms at 30 °C and at 45 °C, filamentous fungi and yeasts, and Staphylococcus aureus among the treatments. An increase in fatty acids levels was observed for the reduced-sodium cheeses, with the exception of conjugated linoleic acid. Ten sensory descriptors were reported for Coalho cheese using a free listing test. The consumer test indicated that the partial replacement of up to 50% NaCl by KCl may be a viable alternative.

Processamento do tomate (lycopersicumexculentum) seco com substituição do cloreto de sódio pelo cloreto de potássio: estudo da avaliação da desidratação osmótica seguida de secagem

&lt;p&gt;The objective of this work was to evaluate the osmotic dehydration (OD), with the substitution of sodium chloride (NaCl) by potassium chloride (KCl), followed by the drying, in dry tomato processing. Italian -tomatoes were collected . After the selection, homogenization and sanitization, samples were taken from the tomato in natura for the physical-chemical analysis. Then, 13 (thirteen) solutions of Sucrose, NaCl and KCl in their different combinations were used in OD. After that, samples of the 13 treatments were collected for physico-chemical determinations and variables of weight loss (PP) and water loss (PA). Subsequently, all treatments were submitted to oven drying with forced air circulation at 60 ° C for 17 hours. After the drying, the treatments that presented final moisture of not more than 25% were selected for analysis of the physicochemical parameters. All the analyzes followed the technical norms established by the Adolfo Lutz Institute. The results of the in natura fruit presented values of 95.68% of humidity; 0.28 ATT expressed as citric acid; 3.84 pH and 4.75 ° Brix. After the DO of the 13 treatments, the tomatoes showed variations of 90.76 to 95.19% of humidity; 0.24 to 0.36 ATT expressed as citric acid; 3.46 to 4.28 pH and 4 to 7.1 of Brix. As for the initial and final OD mass, it has been verified that the percentages of water loss and weight present significant values in T6, T8 and T12 treatments . Partial or total substitution of NaCl by KCl in the amounts of 5 and 10% studied in the osmotic process demonstrates efficiency in the reduction of the drying time to obtain the desired moisture when compared to the treatments in which there is no introduction of KCl. Therefore, the use of KCl as a partial or total substitute for NaCl in the osmotic dehydration of tomato is considered tefficient in drying.Palavras-chave: Perda de água, secagem, redução de sódio, saúde.&lt;/p&gt;

Sodium reduction and flavor enhancers addition: is there an impact on the availability of minerals from probiotic Prato cheese?

The effect of partial substitution of NaCl with KCl and the flavor enhancers addition (arginine, yeast and oregano extract) on the bioaccessibility of five minerals (Mg, Ca, K, P and Zn) from potentially Probiotic Prato cheese was evaluated. After 1, 30, and 60 d of refrigerated storage (processing, ripening and refrigerated storage), total concentrations of Mg, Ca, K, P and Zn were determined by flame atomic absorption spectrometry (FAAS). In addition, bioaccessibility assay with a simulated (in vitro) gastrointestinal digestion model was used. Sodium reduction and the addition of flavor enhancers revealed some significant (p < 0.05) changes in the chemical composition and pH of potentially Probiotic Prato cheese. Overall, P was the least-available element (∼4.8%). The mean availability of Mg, Ca, K and Zn was significantly ∼42.4%, 12.7%, 10.9%, and 9.2%, respectively. Na reduction and addition of flavors enhancers increased the bioaccessibility of Mg (∼6.4%), Ca (∼2.5%), K (∼4.5%), Zn (∼6.0%) and P (∼2.5%). The in vitro method supports accurate determination of the effect of the sodium reduction and addition of flavor enhancers on availability of mineral compounds ingested from potentially probiotic Prato cheese during processing, ripening and refrigerated storage.

Effects of partial substitution of NaCl on gel properties of fish myofibrillar protein during heating treatment mediated by microbial transglutaminase

The effects of partial substitution of NaCl with KCl, MgCl2 and CaCl2 on gelation properties of myofibrillar protein (MP) mediated by microbial transglutaminase during the heating process were studied, including texture, color, water-holding capacity, rheological properties, Raman spectra and microstructure. Ranking of chlorinated salts efficiency showed NaCl > KCl > MgCl2 > CaCl2. The NaCl and KCl groups of MP gels exhibited similar water-holding capacity and gel strength. The gel strength was all decreased in the MP gels containing KCl, CaCl2 and MgCl2 compared to the NaCl group, while the KCl group reduced the gel strength to a less extent. The rheological properties of NaCl and KCl groups showed significant higher G′ and G″ values compared to the control group. Thus, the utilization of chlorinated salts substitutes is a promising way to reduce sodium content in fish products. These results could be used for references in developing low-sodium meat and fish products.

Effects of substitution of NaCl with KCl, L-histidine, and L-lysine on instrumental quality attributes of cured and cooked pork loin

ABSTRACTThis study evaluated the effect of substituting of NaCl with varying amounts of a combination of KCl, L-histidine (L-his), and L-lysine (L-lys) on the instrumental characteristics of cooked loin. Fifteen cooked loins were produced by replacing 0%, 25%, 50%, 75% and 100% of NaCl with the salt substitute. Experiments were conducted in triplicate to determine the water-holding capacity (WHC), and T2 relaxation time, and a texture profile analysis (TPA) and color determination test were also performed. T2 relaxation time analysis indicated that substitution affected the distribution of water by increasing the proportion of immobilized water and improving the WHC. results of TPA and color tests showed no adverse effect from using the experimental treatments. Results showed that 50% was the most suitable substitution ratio (actual 30.15% subsitution level of NaCl), for which the Na content was approximately 27% lower than that of the control for cooked loin.

Partial substitution of NaCl by KCl and addition of flavor enhancers on probiotic Prato cheese: A study covering manufacturing, ripening and storage time

Cheese is a suitable matrix to deliver probiotic strains but it contains a high amount of sodium. The effect of partial substitution of NaCl by KCl and the addition of flavor enhancers (l-arginine, yeast and oregano extract) on probiotic Prato cheese was investigated after 1, 30, and 60 d of refrigerated storage (immediately after manufacturing, and during ripening and storage). Microbiological (lactic acid bacteria and probiotic Lactobacillus casei 01 counts and survival under gastrointestinal conditions), physicochemical (pH, proteolysis, fatty acids), bioactivity (antioxidant effect and angiotensin I-converting enzyme inhibitory activity), rheological, and water mobility by means of time domain low-field nuclear magnetic resonance were investigated. Significant changes in probiotic survival were observed; however, the sodium reduction and the addition of flavor enhancers did not constitute an obstacle to L. casei 01 (>108 CFU/g) during storage. Slight changes were observed in proteolysis, bioactivity, water mobility, texture profile, and fatty acids of the cheeses as a function of the flavor enhancer added. The sodium reduction and the supplementation of Prato cheese with probiotic cultures may be an effective alternative to the production of a potentially functional cheese.

Quality characteristics of fat-reduced emulsion-type pork sausage by partial substitution of sodium chloride with calcium chloride, potassium chloride and magnesium chloride

Effects of substitution of sodium chloride (NaCl) by other chloride salts, such as calcium chloride (CaCl2), potassium chloride (KCl), and magnesium chloride (MgCl2) on quality characteristics of fat-reduced emulsion-type pork sausages were investigated in this study. The pH, cooking loss, lightness and overall acceptability of sausages were gradually worsened by substitution of NaCl with CaCl2 (P < 0.01). Substitution of NaCl with MgCl2 raised water-holding capacity and instrumental colors except redness depending on the substitution level (P < 0.05). However, substitution of NaCl with KCl did not affect quality characteristics of fat-reduced emulsion-type sausages. Substituting up to 25% of the NaCl with MgCl2 or 5% of the NaCl with CaCl2 resulted in better quality than the control. Therefore, NaCl substitutions up to 50% with KCl, up to 25% with MgCl2 or 5% with CaCl2 are acceptable for processing fat-reduced emulsion-type pork sausages without causing quality degradation. However, substitution levels over 5%, CaCl2 caused gradual degradation in water-holding capacity and color.

Tetrodotoxin-insensitive electrical field stimulation-induced contractions on Crotalus durissus terrificus corpus cavernosum.

Reptiles are the first amniotes to develop an intromitent penis, however until now the mechanisms involved in the electrical field stimulation-induced contraction on corpora cavernosa isolated from Crotalus durissus terrificus were not investigated. Crotalus and rabbit corpora cavernosa were mounted in 10 mL organ baths for isometric tension recording. Electrical field stimulation (EFS)-induced contractions were performed in presence/absence of phentolamine (10 μM), guanethidine (30 μM), tetrodotoxin (1 μM and 1mM), A-803467 (10 μM), 3-iodo-L-Tyrosine (1 mM), salsolinol (3 μM) and a modified Krebs solution (equimolar substitution of NaCl by N-methyl–D-glucamine). Immuno-histochemistry for tyrosine hydroxylase was also performed. Electrical field stimulation (EFS; 8 Hz and 16 Hz) caused contractions in both Crotalus and rabbit corpora cavernosa. The contractions were abolished by previous incubation with either phentolamine or guanethidine. Tetrodotoxin (1 μM) also abolished the EFS-induced contractions of rabbit CC, but did not affect EFS-induced contractions of Crotalus CC. Addition of A-803467 (10 μM) did not change the EFS-induced contractions of Crotalus CC but abolished rabbit CC contractions. 3-iodo-L-Tyrosine and salsolinol had no effect on EFS-induced contractions of Crotalus CC and Rabbit CC. Replacement of NaCl by N- Methyl-D-glucamine (NMDG) abolished EFS-induced contractions of rabbit CC, but did not affect Crotalus CC. The presence of tyrosine hydroxylase was identified in endothelial cells only of Crotalus CC. Since the EFS-induced contractions of Crotalus CC is dependent on catecholamine release, insensitive to TTX, insensitive to A803467 and to NaCl replacement, it indicates that the source of cathecolamine is unlikely to be from adrenergic terminals. The finding that tyrosine hydroxylase is present in endothelial cells suggests that these cells can modulate Crotalus CC tone.

Use of alternative curing salts for processing salamis.

ObjectiveThis study was performed to determine effects of different curing salts on the quality of salamis and to assess feasibility of using NaCl-alternative salts.MethodsVarious types of curing salts (KCl or MgCl2) as well as NaCl (sun-dried or refined) were incorporated for processing of salamis. The proximate composition, fatty acids, nucleotide-related compounds, and free amino acids of the salamis were analyzed during 40 days of ripening.ResultsThe substitution of NaCl by KCl caused higher fat and ash content, but lower moisture content of the salami after 20 days of ripening (p<0.05). Compared with the sun-dried NaCl, use of KCl in salami also led to greater inosine 5′-monophosphate whereas refined NaCl had more inosine (p<0.05). KCl-added salami also had a higher C12:0, C17:1, and C20:0 than other types of salami (p<0.05). MgCl2-added salami had higher content of free amino acids compared to the other salamis (p<0.05).ConclusionAlternative curing salts such as KCl and MgCl2 could substitute NaCl in consideration of quality factor of a fermented meat product. Especially replacement of NaCl with KCl will be a suitable strategy for developing relatively low sodium salami products without compromising product quality.

Free-sodium salts mixture and AlgySalt® use as NaCl substitutes in fresh and cooked meat products intended for the hypertensive population

This work aims at reducing the use of added NaCl in processed meat products because of its negative effects on hypertensive population by replacing it by sodium-free salts mixture (SM: KCl, MgCl2 and CaCl2) in fresh and cooked sausages. The technological, sensory, and microbiological effects of SM were compared with a commercial replacer based on seaweed extracts (AlgySalt®). A total substitution of NaCl with the latter and a partial one with SM (80% and 50%) were studied in cooked sausages and a total NaCl substitution with both substitutes was performed in fresh sausages. As a result, hardness increased in AlgySalt® reformulated samples, while it decreased when 80% SM were used. Whereas, AlgySalt® induced less cooking loses than SM. To some extent, microbiological counts showed a similarity between reformulated and control samples for both sausage types, whereas reformulated products containing SM revealed better sensory properties for both meat products. Therefore, using SM as NaCl replacer is adequate for processed meat products.

Effect of sodium reduction and flavor enhancer addition on probiotic Prato cheese processing

The effect of partial substitution of NaCl with KCl and the flavor enhancers addition (arginine, yeast extract and oregano extract) on Probiotic Prato cheese processing with (L. casei 01, 7logCFU/mL) was investigated. Microbiological (lactic acid bacteria and probiotic counts), physicochemical (proximate composition, pH, proteolysis), bioactivity (antioxidant and angiotensin I-converting enzyme inhibitory activity), rheological (uniaxial compression and creep tests), water mobility (time domain low field magnetic resonance), microstructure (scanning electron microscopy) and sensory evaluation (consumer test) were performed. Sodium reduction and flavor enhancers addition did not constitute an obstacle to the survival of lactic and probiotic bacteria. Proximate composition, antioxidant and angiotensin I-converting enzyme inhibitory activity, and the rheological parameters were affected by the addition of flavor enhancer. No change in the fatty acid profile of cheeses was observed while good performance in the consumer test was obtained by the addition of yeast extract and oregano extract. Prato cheese can be an adequate carrier of probiotics and the addition of different flavor enhancers can contribute developing this functional product in the cheese industry.

Development of a novel smoke-flavoured trout product: An approach to sodium reduction and shelf life assessment

This work aimed to develop a reduced sodium smoke-flavoured trout product with similar physico-chemical traits and sensory quality to commercial smoked trout. In a first phase, a reduced sodium smoke-flavoured trout product was developed by a novel smoke-flavouring process using water vapour permeable bags. In a second phase, the obtained product's microbial and physico-chemical quality was evaluated for 42 cold storage days. A smoke-flavoured trout product with similar physico-chemical characteristics and sensory acceptance to commercial smoked trout was achieved through smoke-flavouring with water vapour permeable bags. Partial substitution of NaCl for KCl led to a 42% sodium reduction in the smoke-flavoured trout and did not affect its physico-chemical traits, sensory attributes and hygienic quality throughout the storage. During shelf life study, no sample exceeded the limits of acceptance proposed for physico-chemical and microbial parameters, except for mesophilic bacteria, which limited the product shelf life to 1 month.

Effect of partial substitution of sodium with potassium chloride in the fermenting brine on organoleptic characteristics and bioactive molecules occurrence in table olives debittered using Spanish and Castelvetrano methods

SummaryThis research was aimed at testing whether the partial substitution of NaCl with KCl (50 or 75% relative substitution) in the fermenting brine of green table Nocellara del Belice olives debittered using two used method (Spanish and Castelvetrano) affected the presence of nutritionally relevant molecules (tocopherols, carotenoids, squalene, phenolic compounds) or the organoleptic characteristics of the table‐ready product. Results support the effectiveness of NaCl partial substitution by potassium chloride for olive processing, with the advantage of a significant decrease in the amount of sodium in the end product. The presence of the main bioactive molecules remained substantially unchanged, but KCl was associated with an increase in bitterness in both debittering methods. However, bitter properties (bitter, persistence and aftertaste) of olives obtained through the modification of Castelvetrano method still remained below those debittered with the classic Spanish method preserving, for such olives, the characteristic of ‘sweet olives’.

Impact of NaCl reduction on lactic acid bacteria during fermentation of Nocellara del Belice table olives

Table olives are widely consumed worldwide but, due to the presence of NaCl in fermenting brines, they contain high levels of sodium. A promising strategy to lower sodium content is the reduction or substitution of NaCl in brines with other chlorides. However, these procedures may impact safety, spoilage, as well as quality and technological properties, including the evolution and final composition of the fermenting microbiota. In the present work the effects of partially replacing NaCl with KCl in fermenting brines on the microbiological quality of Nocellara del Belice olives produced by Spanish style (Sivigliano) or Castelvetrano methods have been analyzed. In both cases, the fermentation steps were performed in parallel, in brines containing either NaCl alone, or partially replaced with different proportions of KCl (25, 50 and 75%), while maintaining a final saline concentration of 9% (Sivigliano method) or 7% (Castelvetrano). To compare microbial dynamics in the experimental brines, changes in bacterial ecology were monitored during fermentation with a polyphasic approach, including both microbiological methods and culture-independent techniques based on DGGE and NGS analysis. The main microbial groups detected in the olive microbiota from both production procedures were LAB and yeasts. Overall, the data demonstrate that partial replacement of NaCl with KCl does not increase the risk of contamination, nor the overgrowth of pathogens or spoiler microbes.