We have developed LACTOPRO starter enrichedspent culture of lactic acid bacteria and yeasts to promote the conversion of organic waste into plant substrate

One of the LIFE for Acid Whey project goals is to present a closed cycle of complete utilisation of by-products emerging from milk processing. In this way, we want to contribute in a broader context to greener management in the food industry and reduce waste generation.

The processing of milk into cheese and other dairy products by the fermentation process produces a large amount of whey, rich in lactose and lactic acid microorganisms. As part of development activities, the concentrated whey residue with lactic acid culture was used to develop LACTOPRO starter (P-202100089).

LACTOPRO starter is used to accelerate the fermentation of biological waste, which is disposed of in airtight containers. LAKTOPRO starter can also be used for the preparation of biological waste for composting in a garden composter or for the direct improvement of garden soils or plant substrates.

About the garden composting of organic waste for soil improvement

The benefits of decomposing household and garden waste by composting to improve the soil and protect the environment are well known today. We know that it is a controlled decomposition of organic material into compost, which enriches the soil with organic matter and plant nutrients. However, fewer are familiar with the various possible ways of organic waste decomposition. The so-called classical composting is the decomposition of organic waste in the presence of sufficient air and moisture and an appropriate ratio of nitrogen and carbon in the plant material. Decomposition produces CO2 and water, and the rest represent harder degradable organic molecules that form compost. In the absence of air, high moisture content and too low carbon content in organic matter, anaerobic microorganisms will predominate. Their metabolic product is, among other things, methane and other volatile substances with an unpleasant odour. Usually, we want to avoid such a twist in the decomposition of organic matter in the composter. However, the organic matter can also be fermented under suitable conditions, which is described below.

Bokashi fermentation technique of organic waste for soil improvement

Fermentation is the process of breaking down more easily degradable organic substances, such as sugars, in the absence of oxygen and help of microorganisms. The technique is successfully used in preserving foods, such as pickling vegetables. A similar approach can be applied to organic household waste. This approach is the so-called Bokashi composting technique, which originates from Japan. The term bokashi is a Japanese term for fermented organic matter. 

For this type of household waste treatment, we need a bucket that can be sealed. The waste is put in the bucket in layers by pushing it and squeezing the air each time. Besides, we must ensure that the resulting liquid drains out to provide just the right level of humidity at which the fermentation processes occur. An accelerated and correct fermentation process is achieved by using a suitable inoculum in the form of a starter that is rich in beneficial microorganisms. Conventional starters are prepared on the basis of wheat husks or other cellulosic material, molasses and so-called effective microorganisms. As part of the LIFE for Acid Whey project, we designed an innovative and patented formulation of starter, which is described below.

Development of LACTOPRO starter for lacto-fermentation of organic waste

LACTOPRO starter was developed by a unique process of enrichment of selected plant cellulosic material with the spent culture of lactic acid bacteria and yeasts originating from a by-product of milk fermentation, such as whey. The multiplied number of beneficial microorganisms in the resulting starter is essential for the rapid and properly directed fermentation of organic waste. In the dried starter, the microbes are in a dormant stage. Starter kept in a cool, dry place, away from direct sunlight, will remain effective for several years.

With the fermentation process and the addition of LACTOPRO starter, the organic waste decomposes faster than with the usual garden composting method. It takes about fourteen days to complete the fermentation. Fermentation also requires little space. It can be performed in a small closed bucket, also indoors, as unpleasant odours are not forming. The resulting product is a substrate rich in plant nutrients, which can be buried in ordinary garden compost or directly into the ground. The resulting liquid, which is removed, can be utilised diluted as a plant fertiliser or even to unclog drains since it is acidic with a low pH value.

Preparing a bucket system for the fermentation of organic waste by LACTOPRO starter

Various versions of Bokashi fermentation buckets are available on the market. The system of buckets for fermentation of organic waste in the apartment can also be prepared yourself. You need at least two bucket systems for continuous fermentation of organic waste. Fill the first bucket for two weeks. Live it to ferment for two weeks before emptying it into compost or burying directly into the garden soil. At this point, you start filling the second bucket.

For the usual amount of household organic waste, ten to twenty-litre buckets with lids that allow an airtight closure are sufficient.
During the fermentation of organic waste, the liquid is released, draining to the bottom of the bucket. The amount of leachate depends on the type of waste. For a more favorable course of fermentation, the liquid should be regularly removed or separated from the waste.

One way is to use two identical buckets placed inside the other to leave a few inches of space between them. Drill holes in the bottom of the upper bucket so that the liquid can drain into the lower bucket. Remove it by lifting the top bucket and draining the liquid. The liquid contains nutrients and beneficial microorganisms, but it is very acidic. It can be strongly diluted with water (1: 150 - 1: 200) and used as plant fertiliser, or it can be used undiluted as a natural means of unclogging drains.

Preparation of a system of two buckets for fermentation and collection of the resulting liquid.

Preparation of a fermentation system in a single bucket with absorbent material at the bottom to collect the liquid.

Fermentation of organic waste using LACTOPRO starter in prepared bucket systems

1. STEP: FERMENTATION

Use a prepared bucket that can be sealed. Collect organic kitchen waste in a container and put it in a bucket daily. Cut larger pieces into smaller ones to prevent the formation of larger air spaces in the bucket.

Sprinkle a handful (2-3 tablespoons) of LACTOPRO starter over the organic waste deposited in a three to five-centimetre layer. Press waste and the starter strongly with a suitable lid or plate to reduce air space. Then close the bucket tightly.

When the older layers start to ferment, a sour odour is detected in the open bucket. From the closed bucket, the odour should, however, not escape. We may notice white mould growing in the bucket, which signifies that the LACTOPRO starter is working. Different colours of mould (green, blue, or black) indicate that the bucket is overgrown with unwanted mould. In such a case, add more starter over the next few days. For a favourable fermentation process, the waste and starter moisture content should be around 30%. For orientation, water should not leak from the material when it is squeezed into the fist at this level of humidity, and the material must retain a compressed shape. 

When using a two-bucket system, remember to remove liquid every few days. 

Once we have filled the first bucket (or bucket system), we start using the second bucket and leave the first one closed for two weeks. After two weeks of fermentation, the bucket is ready for use in the next round. If the buckets are sealed, they can also be stored for several months. There is nothing wrong if fermented organic waste freeze if left outside for the winter.

2. STEP: COMPOSTING

After at least fourteen days of fermentation, the organic waste is ready for composting. Although organic waste will retain its original appearance after fermentation, its cellular structure will be altered and softened, allowing rapid decomposition during composting using one of the following methods: 

BURIAL INTO GARDEN SOIL: Dig a hole or ditch 30-45 cm deep in the garden, empty the fermented organic waste into it, mix it and cover it with soil. Buried fermented waste should be left for about two weeks to stabilise the pH of the soil and complete the decomposition of waste. Only then the plants are planted or sown in the soil. 

Aerobic microorganisms and other organisms in the soil will grow fast over the waste and decompose the fermented waste to the end. In two to six weeks, the waste is completely decomposed. The final compost thus enriches the soil with moisture, plant nutrients and organic matter. The same place in the garden can be used over and over again for the disposal of fermented organic waste. 

DISCHARGE IN THE COMPOSTER: Fermented organic waste can be disposed of in an external composter. As fermented waste has an acidic odour, it can be mixed into the material in the composter or covered with leaves. The odour will dissipate quickly. Meanwhile, moist fermented waste, rich in nitrogen and beneficial microorganisms, will speed up the composting process.