Product, Process & Package technology

Acrylamide in potato products

Acrylamide is a toxin that can potentially occur in high concentrations in heated starchy foods (via the Maillard reaction) and especially in potato products such as crisps and French fries. This FIRM project investigated factors influencing the formation of acrylamide in potato products by monitoring levels of acrylamide and acrylamide precursors (reducing sugars, asparagine) in different potatoes cultivars subjected to different storage regimes and processing methods. A risk assessment study was undertaken by the Biosystems Engineering Department at University College Dublin to estimate intakes of acrylamide from potato products from various cohorts of the Irish population. Research indicated the following conditions/factors for acrylamide formation in potato products: (i) storage of potatoes at circa 3°C promotes reducing sugar formation; (ii) using some varieties of ware potatoes for domestic preparation of French fires as these varieties had very high levels of reducing sugars at some sampling points; (iii) deep frying French fries at high temperatures (>190°C) as acrylamide formation increases at higher temperatures. Pre-frying processing techniques reduced acrylamide formation in French fries prepared from ware potatoes via leaching of acrylamide precursors from the raw chips. Acrylamide formation was strongly linked to levels of reducing sugars in the uncooked potatoes, and lightness of fry colour was inversely correlated with levels of acrylamide in French fries. Risk assessment studies indicated that the mean intake for acrylamide in Ireland was 0.29 μg/kg/bw/day from French fries and 0.058 μg/kg/bw/day from potato crisps. A status report entitled ‘Acrylamide in Potato Products’ (see more...) was prepared as part of this project. Further information is available in an End-of-Project Report (see more...). The overall results have been disseminated widely to the potato trade and to consumers. (nigel.brunton@teagasc.ie)

Reduced salt ethnic ready-meals

Ethnic ready-meals (e.g. Indian, Italian and Mexican dishes) typically consist of meat, sauce, cheese, pasta, salt, spices, and additives. However, health professionals are increasingly concerned with the high intake of non-discretionary sodium from salt and sodium-containing additives in these products. In order to label as “low salt”, a food must not contain more than 0.12g sodium/100g, and for “very low salt” not more than 0.04g/100g. Any reduction in sodium content must be accompanied by the assurance of food safety for the consumer and the provision of technical data on reformulation strategies, survival of pathogens/spoilage bacteria, and sensory properties of the novel products for the producer. This FIRM project is in partnership with Dr. Martin Wilkinson (University of Limerick) and is developing a range of ethnic ready-meals with a considerably reduced sodium content compared to existing products. This is being achieved by (a) developing low sodium ingredients e.g. cheese and sauces, (b) sourcing low sodium ingredients e.g. spice preparations and (c) using lower added salt levels in the formulation. The key areas of (1) the microbiology and (2) the sensory properties of low sodium ethnic ready-meals are being addressed. (nigel.brunton@teagasc.ie)

Novel fruit products with emphasis on apples

This project is a component of a major EU Integrated Project (ISAFRUIT) (www.isafruit.eu) with the overall theme ‘healthy fruit for a healthy Europe’ and is in start-up phase. The component at AFRC embraces a large number of trials on apples and other tree (‘permanent’) fruits as follows:---

1. Increasing fruit sweetness by osmotic treatment
2. Vacuum infusion of apple slices
3. Firming of apple slices by enzymatic and chemical treatments
4. Colour and texture retention/stability in apple slices intended for fresh fruit salad and process applications.
5. Total antioxidant capacity in apple slices
6. Total antioxidant capacity in a generic fruit salad model
7. Quality tests on apple samples purchased in supermarkets
8. Texture modification in apple purées/pulps
9. Preparation of model chilled, frozen, freeze-chilled and ambient-stable apple products
10. Preparation of model sous vide apple products
11. Product applications to partner samples
12. Product applications to other permanent fruits

Fresh-cut apple slices have been produced containing a prebiotic, algal calcium and infused honey (see more...), and also a range of apple-based ready desserts with functional ingredients ready-desserts (see more...). These trials are continuing and apple samples are being received from project partners in other countries. (Ronan Gormley)

Freeze-chilling and sous vide processing

Freeze-chilling of food involves freezing and frozen storage followed by thawing and then retailing at chill storage temperatures. Freeze-chilling offers logistic benefits in terms of production, distribution, retailing, and in reducing product recalls. Tests on mashed potato, steamed green beans/broccoli/carrots/salmon, lasagne, tagliatelle and cereal-based products indicated that chilling and freeze-chilling gave similar sensory acceptability scores for the product range, and the results are being used by a number of food companies (see more...). Tests with raw fish fillets indicated that freeze-chilling is a suitable technology for extending the shelf life of prepacked raw fish fillets. Shelf lives of 2-3 days (or 5-7 days with modified atmosphere packaging) were obtained in the current trials for whiting, mackerel, and salmon portions. Fillet freezing at sea or on-farm would be highly beneficial in delivering an extended shelf life in the chilled phase of the freeze-chilled process (see more...). There is ongoing dissemination of the results to ready-meal, seafood, and related companies. (ronan.gormley@teagasc.ie)

Sous vide cooking involves sealing raw or par-cooked food in a vacuumised laminated plastic pouch or container, cooking by controlled heating, rapid chilling and then re-heating for consumption. The chilled storage period is up to 21 days at 0 to 3^oC. The recommended thermal process for sous vide products is 90^oC for 10min, or its time-temperature equivalent. The aim of a recently completed project was to investigate sous vide cooking followed by freezing, as a safe alternative to sous vide/chilling for 10 ready-meal components, i.e. carbohydrates (potatoes, pasta, rice), vegetables (carrots, broccoli) and muscle foods (salmon, cod, chicken, beef, lamb). A P-SV-F system for sous vide processing of the 10 ready-meal components embracing pre-treatments (P), sous vide cook time/temperature (SV), and freezing (F) post sous vide cooking was developed and validated. There was particular focus on the effects of the P-SV-F system on product texture. However, taste panels were unable to detect a significant difference between the sous vide frozen vs chilled samples indicating that freezing was having a minimal, if any, adverse effect on texture. Rate of freezing or long term (up to 8 months) frozen storage had only a small effect on sous vide product characteristics. Research on the safety of the P-SV-F system indicated that a sous vide cook time of 10 min at 90^oC (core temperature) delivered safe sous vide frozen products. However, the possibility of increased pathogen thermotolerance via stress responses resulting from the P-SV-F system needs to be recognised (see more...). A second project on the use of sous vide processing for a range of fish species in savoury sauces has also been completed (see more---EoPR No. 77) and excellent products were produced. (ronan.gormley@teagasc.ie)