Tag Archives: fruit

Should Sun Drying be Rejected as a Food Unit Operation

Papers describing food drying techniques normally list the obvious contamination risks of drying in the open air as a major disadvantage and and based on this dismiss its application. However, the large volumes of food that are sun dried every year and the savings in energy and capital bely this quickly reached conclusion.

Searching the literature and regulations doesn’t give any guidance on the advisability of establishing a new sun drying business.

However, the two videos below show the large scale use of sun drying and the associated technologies applied at Cecilia’s Farm, near Prince Alfred in South Africa.

It seems that the critical point about the sun dried business they run, is that all fruit is washed before further processing and or packaging. Arguably this makes it comparable to fruit which is often not peeled, packaged salad and leafy vegetables. These are grown in the same environment and simply washed before eating.

The massive advantage of sun and to a lesser extent solar drying is that they produce shelf stable foods with minimal environmental impact and low processing and packaging costs.

A Comprehensive Solar Drying Manual – Free Online Information

I happened onto this manual just now and it got me to thinking about solar drying again.

click the image to download the manual

The document was prepared as a training manual for a Zimbabwian project funded by the Austrian Embassy titled Establishment of a production, sales and consulting infrastructure for solar thermal plants in Zimbabwe.

Its a comprehensive manual covering many designs and processes which you will see in illustrations from other documents you have read over the years. The 110 page book contains descriptions of many different dryers as well as examples of many different crops and their dryers. It also presents a great deal of technical data on drying but even though the title of the project nothing about markets, packaging and selling.

Solar drying should be all the rage currently giving its potential to impact global food shortage and climate change – but we still seem to be where we were decades ago.


Gentle Drying of Fruit and Vegetable Purees in a BIRS Spray Dryer.

Here is another story looking at product development focussing on premium products which avoid heat treatment in processing.

The BRIS process uses ambient temperature air which has been dried using heating and silica gel to a few percent relative humidity, in a counter current drying tower.

click the image to visit the website

This application by Naturex, a French company more focussed on natural ingredients for the food & beverage, nutrition and health and personal Care industries, is a first for them. The products main selling point appears to be their good organoleptic properties and their ease and quality of reconstitution.


Bespoke Fruit & Vegetable Washing Solutions?

Sometimes I expect more when I read. Headline like this one, probablyq because I am alive.

click the image to visit the website

Reading further this is a company that sells chlorine and sulphite based chemicals for fruit and vegetable rinsing. They now offer a service based on analysing the untreated water and developing a custom dosage regime for the factory's particular circumstances.


I would have thought that the chemical dosage is normally done on site using trial and error, but it makes publicity and marketing sense.

The Manual on Home-based Fruit and Vegetable Processing – Free Online Information

This is probably the best technical information I have seen aimed at the training of small scale vegetable and fruit processors. The first book covers the principles of post-harvest handling, storage and processing of fruits and vegetables while the second provides recipes and guidance to put these principles into practice.

 click image for free acces to these books

The books We’re developed for trainers working with household processors in Afghanistan, but the information is so comprehensive that it will be useful for a range of users including the new small scale food processing enterprise.

The first book of 85 pages covers the following in detail, using a clear and simple style supported by many photographs and drawings.





  • Principles of food preservation 
  • Overview of fruit and vegetable processing techniques
  • Summary of small-scale fruit and vegetable processing techniques
  • Processing pre-treatments for fruit and vegetables 
  • Description of processing methods for fruit and vegetables  



The second book of around 90 pages covers the detail of producing a whole range of products as listed below from the table of contents:


  • Processing outline for dried fruit and vegetable
  • Dried tomato 
  • Dried apricots
  • Dried onions
  • Dried apples


  • Processing outline for Jam and Jelly 
  • Fruit jam or jelly – process details and quality 
  • Apricot jam
  • Carrot and lemon jam
  • Cherry jam
  • Mulberry jam
  • Apple jam
  • Apple jelly


  • Processing outline for sauce and chutney
  • Sauce and chutney – process details and quality assurance
  • Italian style tomato sauce
  • Italian style tomato sauce
  • Tomato paste
  • Tomato sauce or ketchup
  • Tomato puree or simple concentrate
  • Tomato concentrate (non-cook method) 
  • Coriander chutney (chatni gashnizeh)
  • Vegetable chutney
  • Tomato chutney (Chatni Badenjani Romi)
  • Chili chutney (Chatni Morchi Sorkh/Sabz )


  • Processing outline for lactic acid fermented pickles (atchar)
  • Fermented pickles – process details and quality assurance
  • Pickled cucumbers
  • Mixed pickles
  • Pumpkin pickle 


  • Process outline for fruit and vinegar
  • Fruit vinegar – quality assurance and processing notes
  • Tomato vinegar
  • Mulberry vinegar

If you have any interest in processing vegetables and fruit, these books are really highly recommended.

A COP-17 Inspired Look at Carbon Footprints in Food Chains

With the United Nations and many of the world leaders in climate change on their way to Durban for COP-17, I think it might be worthwhile focussing on some Food Chain and Food Processing Issues that effect the carbon footprint of the food we eat.  
There is no lack of information and discussion in the area, so I will not be trying to give you a full picture, but rather I will present some of the things that interest me and maybe identify places you can go to get information. 
To start if off I suggest you have a look at this paper, that was publicised 5 years ago when the whole let’s not import food from afar was first voiced and seemed to make sense. 

click the image to visit the website

The first think that strikes the reader is the complexity of the analysis necessary to evaluate the carbon impact of a food product sitting on the plate of the consumer. Not only are there a whole range of possibilities but all activities in the Value Chain need to be considered in detail. One of the most complex issues that makes the comparison of data very difficult is where is the boundary drawn within which the carbon foot print is calculated – must the evaluation go back to the mining of the iron ore which was used to make the steel that forms a filler valve? 


What this and a study of the document clearly shows is that it is most likely to make simple comparisons without fully understanding all value chains. even then one may worry that it’s too easy to “pull the wool” over the readers eyes in defining how the carbon footprint is evaluated in any particular case. 


This obviously makes the simple “mines better than yours argument” impossible to make without detail investigation and infant many counter intuitive results have allready been identified by detailed like cycle analyses. 

The conclusion and recommendation of this report, on only a small sector of the food industry, are rather disappointing as they are rather imprecise identifying many valid issues and needing to call for “much more study”. 

An interesting comment in the paper, was that the carbon footprint is probably closely related to the perishibillity of the product. This since cold chain operation, transport and cold storage as well as their effect on waste are all big factors in the emission of green house gasses. 

Finally, for technologists and scientists it’s important to note that reductions is ghg emissions are probably just as likely to come from behavior change as from new technology.

Lost Crops of Africa – Fruits – Free Online Technical Manual

I posted some general thoughts on this book when it was published a few years ago. The other day I came across it again, on the USAID site as a free download, although its published by The National Academic Press . I felt it would be worthwhile reminding readers of the book and giving them the link to the download.

Http pdf usaid gov pdf docs PNADS877 pdf

from: USAID
(click image for full story online)

The book covers cultivated and wild fruits in two parts. Each part presents general information on the fruits’s potential role in addressing issues such as Malnutrition, Food Security, Rural Development and Sustainable Landcare. The part on Wild Fruit also covers particular issues such as
Increasing Wild Fruit Usage, Developing Wild Fruits, Nutrition, Sustainable Forestry and Social Difficulties.

Both parts then cover a large number of fruits separately and in detail.

The cultivated fruit section covers Balanites (Balanites aegyptiaca), Baobab (Adansonia digitata), Butterfruit (Dacryodes edulis), Carissa (Carissa species), Horned Melon (Cucumis metulifer), Kei Apple (Dovyalis caffra), Marula (Sclerocarya birrea), Melon(Cucumis melo), Tamarind (Tamarindus indica) and Watermelon (Citrullus lanatus).

While the wild fruits include Aizen, Chocolate Berries, Custard Apples, Ebony, Gingerbread Plums, Gumvines, Icacina, Imbe (Garcinia livingstonii). Medlars, Monkey Oranges, Star Apples, Sugarplum, Sweet Detar (Detarium senegalense) and Tree Grapes.

Each fruit is covered in detail with abundant drawing and photographs and information on all aspects from cultivation to utilisation.

This is an amazing resource which an enormous amount of detail.

Fruit Processing Toolkit – Free Online Manual

This Toolkit is online on the FAO’s INPhO website (International Network of Post Harvest Operations).

It is a comprehensive collection of information that could be used by a range of people from the new entrepreneur looking to understand fruit products and processors to a processors considering expansion into new products.

FAO Fruit Processing Toolkit 1

from: INPhO
(click image for full story online)

It is a comprehensive presentation covering a wide range of fruits, products and information. It is well illustrated with flowsheets and gives detailed information on processes. It presents recipes for different fruits and products and has a good list of references as well as a comprehensive list of equipment suppliers.

To me the only problem is that this information has to be consulted online, which is a problem for those users who don’t have suitable connectivity.

Freshpict, a Zambian Fruit and Vegetable Canner – African Food Processor.

This Zambian company produces a wide range of canned fruit and vegetables.

Suppliers Website

(Click the image to visit the website)


These include a wide range of products using beans, tomatoes, onion, sweet corn, sundried tomatoes, cherry peppers, pineapple, guava, and gooseberries.