Apfelmus

Applesauce is a sweetened puree of apples, and is especially popular in Netherlands. In the Netherlands, an average of 4.5 kg applesauce per person, per year is eaten.

Besides apples, other fruits are often added to the applesauce. However, other fruits are not allowed to exceed a maximum of 10% of the total fruit weight. The minimum refractometer value of 18% is obtained by adding sugar. The natural sugar content of apples is about 10%, therefore, 8 to 14% extra sugar is added.

Additionally, applesauce has to meet to the following requirements:

• Being light and golden yellow in colour
• Have a fresh aroma
• A pH of 3.2 to 3.6
• A malic acid content of between 0.27 to 0.75%
• The correct viscosity (in the Dutch Commodities Act several measurement methods are mentioned.

Traditionally, Goudreinette apples (Belle de Boskoop) are used to produce applesauce. These apples are, however, expensive compared to the increasingly more used Golden Delicious and Cox’s Orange apples. Golden Delicious apples contribute to a good color and the Cox’s Orange ensure a mildly acidic flavor.

Applesauce is mainly eaten as a side dish or dessert. The product does not contain enough vitamins and minerals to replace vegetables. Applesauce production

Mixing

Throughout the year several apple varieties are used for the production of applesauce, it is therefore important to combine the qualities of these varieties into an acceptable applesauce, to maintain a constant quality. The colour, acidity and quality of the apples should be taken into account.

Unripe or green apples make a too sour and too green apple sauce. Using only red apple varieties will produce an applesauce that is too red. By putting the apples in a certain mixing ratio on a conveyor belt, leading to a drum washer, a quality as constant as possible is obtained.

Washing

Using a drum washer, a rotating cylinder-shaped washer with perforated sides, soil, leaf residues, pesticides and rotten spots are removed from the apples. To ensure optimal cleaning of the apples, the nozzles in the drum washer should have sufficiently high water pressure, the drum has to be fully filled and should have brushes. The drums are placed in a tilted position, moving the apples slowly from the highest to the lowest point, where the apples are collected on a conveyor belt. After washing, the bad apples are removed and the apples are stripped of any unwanted parts using a roller band.

Cutting

To prevent enzymatic browning, the enzymes responsible for this reaction have to be destroyed during blanching. The apples are shredded in order to make the whole apple reach the high temperature as quickly as possible and to reduce steam consumption. The shredding/ cutting machine is usually placed above the opening of a steam gun.

Blanching

In a steam gun (a stainless steel tube in which a conveyor screw/ auger conveyor is rotating), steam is injected into the shredded apples, via perforations in the sides of the steel tube. Because the steam gun is placed in an inclined position and the condensed moisture is removed only in part, the steam gun operates in the first part as a water blancher and in the second part as a steam blancher. Despite the large variety of apple species, the proper degree of cooking can be obtained with the correct steam flow rate and product passing time in the steam gun. Overcooked apples will cause the applesauce to be mealy, crème like and undercooked apples will cause an excessive product loss. The thickness of the applesauce can be regulated by draining the released condensation. The drained off condensation water can be processed into apple juice concentrate.

Passing

During the passing process, the apples are crushed to a pulp, this releases the pectin which give the desired consistency to the applesauce, and also any peels, seeds and cores are removed. This is process is carried out with one or two passing machines, in series arranged. Using 2 to 4 rasp bars, the cooked apples are pressed through the sieve openings in the wall (0.6 to 1.0 mm). If the sieve openings are too large this will result in a bad separation process and too small sieve holes will produce an applesauce with a mealy, crème like texture. In case two passing machines are used, the second machine has finer screen (sieve) apertures.

The passing time and the rotational speed of the rasp bars have an effect on the consistency and quality of the applesauce. If the rotation speed is too high the applesauce may get a bitter taste and an undesirable appearance because peels and seeds may also get into the applesauce.

Mixing

In large mixing boxes sugar is added to the applesauce, until a refractometer value of at least 18% is obtained. Furthermore, ascorbic acid is often added in order to prevent discoloration of the applesauce in the top of the packaging. During the passing process the vitamin C that is naturally present in the apples is largely lost. When using with apples with a lower acid content, citric acid can be added to counteract a bland flavour.

After the mixing step, the hot applesauce is pumped to the filling machines.

Filling

The applesauce is heated up (as hot as possible) to a temperature of about 85°C, filled into glass jars or in tins with a coated bottom and lid. Volumetric filling machines are used to precisely measure off the applesauce to fit a jar or tin.

If the applesauce still has a temperature of about 90°C at the time of closing the jars and tins, the pasteurization step can be skipped. However, it is important that the covers and lids are also pasteurized. This can be done by turning the jars upside down.

Pasteurizing

After filling, the containers are pasteurized. Since applesauce is naturally acidic (pH << 4.6), bacterial spores cannot grow, and sterilization is not necessary.

In a tunnel pasteurizer or a hydrostatic continuous sterilization tower, pasteurization is carried out at at 85°C for 25 minutes or at 98°C for 7 to 10 minutes, depending on the volume and type of packaging. A minimum core temperature of 80°C has to be achieved.

Cooling

After pasteurization, the applesauce packages must be cooled down rapidly, ensuring that the average temperature of the applesauce is lower than 35°C.

Storing

The packages can now be labeled and placed on trays with shrink wrap. The applesauce can now be stored outside of the refrigerator for a longer period of time. 

Food Safety & Hygienic Design

On relatively acidic products (pH<4.6) microbial spores can not develop into vegetative (alive) microorganisms, which could potentially spoil or severely contaminate a product. Sterilization or deactivation of spores is therefore unnecessary. The milder pasteurization technique is sufficient to kill vegetative cells and has less of an impact on the flavor.

The production equipment and machinery must be of of a GMP-class. Which means that the machinery and equipment must be visibly clean before use. In case that the machinery cannot be emptied fully (and is clean and set aside dry), the machinery has to be thoroughly cleaned and disinfected before the production process can start again. Cleanable to a microbial level (hygienic design) is not necessarily required for this process. A light microbial contamination should not be a problem.

Even though the product undergoes a heat-treatment after being sealed, this does not give a license to sort less accurate, to clean less frequently or not fully clean the machinery and equipment. Large amounts of heat-stable toxins, originating from microorganisms, can remain toxic even after pasteurization and will keep posing a threat to the health of the consumer.