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Notes on fermentation

Apple peels contain high amounts of polyphenols, and cider apples total active phenolic content can surpass blueberries! Apple juice seems to contain up to 2 grams of polyphenols per liter. This blogpost is a pile of notes.

Related starting points

Water activity
Solid State Fermentation

Milk and fermentation

Simplest form of fermentation for urbanites: Lactic acid fermentation.

LAB-culture: anaerobic fermentation of milk with wild lactic acid bacteria. In fresh pH 6,6 milk stored 3-7 days in an airproof container bacteria ferments lactose into lactic acidand separates proteins into curds . The resulting acid causes antimicrobial effect on competing microbes, reduced oxidative reduction potentia, sour and acidic taste.

Lactose is a disaccharid, that bacteria break down using lactase, into galactose and glucose; then making CO2, lactic acid, ethanol, acetic acid, acetoine, acetaldehyde, formic acid, intermediate or final.

Thermophilic, mesophilic ferment-cultures - 38 deg C vs 24 deg C; Lactobacillus vs Lactococcus or Streptococcus. Zero fermenters for acid only, aromatic fermenters.

Species of bacterial culture is multivariant depending on temperature, nutrients, pH and other conditions, in addition to species already present. Streptococcus thermophilus produce only lactic acid preferring 37-40 deg C. Lactococcus, lactic acid, prefer +30 deg C. Leuconostoc produce aroma. Plural of Lactobacillus, produce lactic acid, alcohols and aromatic compounds. Propionic acid bacteria consume lactate, lactic acid, slow. Bifidobacteria produce lactic- and acetic acid.

Industrial dairy process sterilizes or pasteurizes milk first, then cools milk to preferred temperature, and inoculates with ferment culture. Yogurt finishes in 3 h at 43 deg C, buttermilk takes 20 h at room temperatures.

Inhibitors and pathogens of milk fermentation include but not limited to bacterial phages, lactoperoxidase, dissolved oxygen, free fatty acids, antibiotics, detergent-contamination.

Some links https://ruokaketjuelli.fi/wp-content/uploads/2021/11/Hapanmaitovalmisteet-yleista.pdf Wild bacteria https://www.nature.com/articles/s41598-018-19524-6

Apples and fermentation

Why is this recipe not going to work? Cider, per liter: 900 g apples, 20 g lemon juice, 50 g water with 2 g malt extract, 0,5 g hydrolyzed protein, 30 g glucose (plus optional cider yeast). - because apples contain a lot of solids. Cider is usually made from apple juices pressed from chopped or sliced apples. The fermented solids ferment into pulp puree, a mousse unlike a cider. Simply, over >50% by vol should be juice.

Greg Peck: Cider Science: It’s about the apples https://youtu.be/pktzm0kRKJA The Wittenham Hill Cider Pages http://www.cider.org.uk/ https://brewingmischief.com/wild-fermented-cider/

The scientific principles underpinning inconsistencies in cider quality https://www.utas.edu.au/__data/assets/pdf_file/0009/1255239/The-scientific-principles-underpinning-inconsistencies-in-cider-quality.pdf - a temperature of 20°C, a pH of 3.6 and a cultured yeast may be reliable for achieving timely, clean cider fermentation outcomes.

Organic acid & polyphenol profile for Idared and Pink Lady https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6400742/ Cripps pink @ 141 g/L sugar content (Table 1) fermented with EC1118 to 7.9 ethanol vol %, 5.6 g/L sugar, pH 3.76 (Table 2).

The Idared wine fermented with Fermol Blanc strain had shown the highest overall concentration on polyphenols (228.17 mg L−1), the highest concentration of succinic acid (0.35 g L−1) and the lowest volatile acidity (0.38 g L−1).

From the results of this study, it can be concluded that the variety Idared showed more appropriate characteristic for apple wine production in respect of the variety Cripps Pink.

https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC5511608/ https://www.mdpi.com/2227-9717/9/3/502/htm

Generic fermentation parameters

Arrayo-Lopez, Effects of temperature, pH and sugar concentration on the growth parameters of Saccharomyces cerevisiae, S. kudriavzevii and their interspecific hybrid

- fastest growth for S. c. T73 occurred at 32 C, pH 4.6, 110 g/L sugar. This may not be optimal for cider. For S. c. - 1802 284 g/L sugar prevented fermentation, and 24 C was max.

Saccharomyces uvarum, cold temperature yeast https://academic.oup.com/femsle/article/177/1/177/757708

* pH below 3.8 - if not, adjust with acidic fruit. Some dislike citric acid in cider (if enough, there is always some). * temperature 15-20 deg C. (yeast dependent) * Anaerobic container with positive pressure release for CO2, in dark. * Sugar content >110 g/l

Deep dive into yeast nutrition -webinar https://www.youtube.com/watch?v=V3NfZeR05Wc

100 g of sucrose is 0.292 mol, and stoichiometrically 1 mol sucrose yields 4 mol EtOH, so you'd expect to get 54.0 g, which is about 68.3 mL. https://www.homebrewtalk.com/threads/how-much-pure-alcohol-will-100g-of-white-sugar-produce.185736/

Apple sugars and starches

Sugar-, acid- and phenol contents in apple cultivars https://www.nature.com/articles/1602430

Apple fruit starch https://www.sciencedirect.com/science/article/abs/pii/S0144861705004911

Starch in apple juice Non pasteurised unripe apple juice had as much as 8 g/L starch https://www.sciencedirect.com/science/article/abs/pii/S0308814603006010 YAP was able to inhibit the starch digestive enzymes including α-amylase and α-glucosidase https://www.sciencedirect.com/science/article/abs/pii/S1756464619301288

Amino acids and cider

https://onlinelibrary.wiley.com/doi/full/10.1002/jib.519 https://onlinelibrary.wiley.com/doi/full/10.1002/jib.318 https://pubmed.ncbi.nlm.nih.gov/25920613/

https://www.eaton.com/content/dam/eaton/markets/food-beverage/knowledge-center/white-papers/yeast-nutrients-can-nitrogen-in-the-form-of-ammonium-work.pdf - Addition of ammonium increases yeast cells numbers and fermentation speed. Reduces fermentation time, full alcoholic fermentation more likely without delayed fermentation. - Amino acids in yeast autolysate: ~2-4 % dry matter - N content: below 0.5 % dry matter - optimum supply of 60 million cells/ml requires 120 mg/l of nitrogen. - ? n. 0.1 g mallasta/l

https://www.frontiersin.org/articles/10.3389/fmicb.2017.02554/full https://pricklycider.com/2022/02/05/cider-words-natural-preservatives/ https://en.wikipedia.org/wiki/Yeast_assimilable_nitrogen#cite_note-Zoecklein-1

Kaljamallas, ravinnelähde https://www.foodie.fi/products/834 Punaherukka https://fineli.fi/fineli/fi/elintarvikkeet/445?foodType=ANY&ingredientClass=APPLE&ingredientClass=CITRUS&ingredientClass=FRUITOTH&ingredientClass=BERRY&ingredientClass=FRUITCAN&portionUnit=G&portionSize=100&sortByColumn=component&sortOrder=desc&component=2230&

Oxygen and yeast fermentation

Fermentaatio voidaan rajata tarkoittamaan anaerobisia [2, s. 1; 3, s. 185] sekä mikroaerobisia (happea 21 tilavuus-%) prosesseja [3, s. 185].

3.5 Requirement for oxygen, p. 97 https://www.academia.edu/6545837/Brewing_yeast_and_fermentation

Oxygen Response of the Wine Yeast Saccharomyces cerevisiae EC1118 Grown under Carbon-Sufficient, Nitrogen-Limited Enological Conditions https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497381/ - Table 1 - respirofermentative metabolism - Crabtree effect caused by limited mitochondrial NADH reoxidation - facilitate the development of temporal oxygen addition strategies to optimize yeast - oxygen concentrations impact the physiology of wine yeast cells, improving the yeast fermentative rate as well as yeast viability (55). These effects are partially explained because oxygen is required for sterol biosynthesis, proline uptake, and unsaturated lipid biosynthesis.


Professional | Clarification & Flocculation https://wyeastlab.com/resource/professional-clarification-flocculation/ - Oxygenation affects sterol and fatty acid synthesis and presumably cell surface hydrophobicity (CSH). - Adequate aeration can result in delayed and more intense flocculation.

Microaerobic effect

Relationship of oxygen availability and ethanol production is complex. At very low level oxygen can increase the yield of ethanol. Past microaerobic oxygen levels, yeast produce byproducts like glycerol and acetic acid. Yeast as organism gain energy through fermentation at 1/18 yield versus oxidation. Yeast do aerobic respiration if possible because they get more energy.

Anaerobic respiration in animals gets puruvic acid into lactic acid. In yeast puryvic acid is metabolized into ethanol and carbon dioxide. http://scienceline.ucsb.edu/getkey.php?key=199


Because the biosynthesis of heme requires oxygen, it has been proposed that heme acts as a gauge for oxygen availability. Paradoxical to the need for oxygen for lipid biosynthesis, oxygen can cause yeast degeneration through the formation of highly ROS (O2●−, H2O2 and OH●). https://academic.oup.com/femsyr/article/9/2/226/568736

The role of oxygen in yeast metabolism during high cell density brewery fermentations https://link.springer.com/article/10.1007/s00253-009-1909-8 - 25% kasvunesteen tilavuudesta minuutissä kierrättämällä hapetettu - 45 min aktivoituu YAP1 transkriptiotekijä, cell profileration, anti-apoptosis - 5h steroli-, proliini- ja rasvahappo-aineenvaihduntageenien aktivaatio - 8h vähempi glykoli ja korkeampi trehaloosi-taso

What is mesophilic again? 8)


Onko hiivoilla luonnostaan kyky hajottaa hedelmien pektiini? Re: foorum-kommentit joissa käymisprosessi on hajottanut hedelmänpalaset mössöksi. V: Pectin is demethylated by pectin methylesterase present in the juice, and the resulting pectic acid converted to galacturonic acid by a polygalacturonase secreted by most of the Saccharomyces spp. found in cider fermentations. https://www.sciencedirect.com/science/article/pii/B9780080925431500126

Unless juice has been heat treated, pectin will be broken down by polygalaturonase (pastörisoitu? villimikrobit vai mikä muutti?) https://onlinelibrary.wiley.com/doi/abs/10.1002/jsfa.2740100501

Pectinase-enzyme helps with pulp breaking down and gets more flavor and a clearer cider. https://pricklycider.com/2020/06/03/hard-cider-tip-16-pectic-enzyme/

Influence of apple cultivar and juice pasteurization on hard cider and eau-de-vie methanol content www.sciencedirect.com/science/article/abs/pii/S0960852409013194

Evaluation of polygalacturonase activity in Saccharomyces cerevisiae wine strains https://academic.oup.com/femsle/article/237/2/261/529538

Related stuff

Blow-off tube https://beerandbrewing.com/video-tip-of-the-week-using-a-blow-off-tube/

Yeast starter https://beerandbrewing.com/how-to-make-a-yeast-starter/

Scoby - Symbiotic Colony Of Bacteria & Yeast. Vinegar mother - symbiotic colony of bacteria & yeast wine or cider in acetic acid solution. Kombucha mother - colony of bacteria & yeast on brewed black tea. Garum - fish fermented anaerobically with fish intestine enzyme in 4% brine. Miso - soy fermented with Aspergillus oryzae, Koji. Sauerkraut - white cabbage fermented with lactobacillus in 3% brine.

Acetic acid is a weak organic acid exerting a toxic effect to most microorganisms at concentrations as low as 0.5 wt%. https://pubmed.ncbi.nlm.nih.gov/26142387/

https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_5/b_fdi_23-25/30609.pdf https://www.sciencedirect.com/science/article/abs/pii/S0308814610015487 https://agris.fao.org/agris-search/search.do?recordID=US202100006572 Can produce value-added/innovative bioproducts such as enzymes, antibiotics, bioactive compounds, organic acids, bioethanol https://www.tandfonline.com/doi/abs/10.1080/87559129.2021.2004161 https://www.mdpi.com/2218-1989/12/2/157 https://www.mdpi.com/metabolites/metabolites-12-00157/article_deploy/html/images/metabolites-12-00157-ag.png https://link.springer.com/article/10.1007/s13399-022-02409-0

Fun videos on fermentation and related microbiology

David Zilber at University of Gastronomic Sciences of Pollenzo https://www.youtube.com/watch?v=WImwMC_OasE

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