Hop Research

Research into hop growing began in England in 1894, and has been underpinned by the breeding programme of new varieties since 1904. New varieties have been bred to possess specific desirable attributes such as increased tolerance to disease, higher yields of active components including alpha acids and aroma, modern harvesting techniques to reduce costs and to a/low English bred and grown hops to compete on the world stage.

In broad terms the hop provides 3 characteristics in beer; the bitter taste, flavour and aroma. The first of these, bitterness, comes mainly from a component called alpha acid while the flavour and aroma, a little more intangible, comes from the essential oil characteristics of the hop. Alpha acid is being increased by the development of varieties that have higher alpha acid yields, more hop flowers per plant and the reduction of damage due to disease by the incorporation of disease resistance. Optimum growing conditions are also being sought in terms of cultivation, weed control, irrigation and the application of fertiliser.

Aroma hops require a different approach and although there have been successful attempts to breed new aroma varieties none has exactly reproduced the brewing performance of traditional Goldings or Fuggle hop varieties. One of the reasons is that current methods of hop analysis are not as discriminating as trained beer tasters or drinkers.

The present analysis of the hop oil spectrum is enough to distinguish between hop varieties but is not enough to predict the effect on beer flavour of a new variety. This problem is being addressed from a different perspective in conjunction with BRI (Brewing Research International) using state-of-the-art techniques to identify those components present in only minute amounts, responsible for the hop flavour and aroma in beer. These are being traced back through the brewing process to the original hop so that an acceptable replacement for a Goldings can be identified that is also high yielding and disease tolerant.

The breeding programmes have been carried out using classical techniques whereby the flowers of both the male and female plants are isolated and the pollen of a male variety is used manually to fertilise the desired female variety, producing hybrid seedlings. The selection of new varieties is from these hybrids.

Nearly a century of this hybridisation at Wye College in Kent, now part of HRI, has enabled a huge bank of genetic material to be built up in the form of living plants which have their individual attributes recorded in detail on a database. The scientists at Wye have the technical experience to be able to select from this living bank of plants those which are most likely to give the desired attributes on hybridisation.

In practical terms this has led to the development of high alpha varieties and those which show greater resistance to diseases like downy and powdery mildew. In recent years dwarf hops (First Gold, Herald and Pioneer) have emerged having the commercial benefits of low capita] investment, enhanced management flexibility and lower labour costs. In addition they have undoubted environmental advantages. Beneficial predator insects like Phytoseiulus persimilis, which destroy harmful insects, are more active, and the application of pesticide via an enclosed sprayer enables less pesticide to be used and reduces spray drift into the environment.

What the brewers want is, on the one hand, the cheapest consistent and reliable supply of alpha acids and on the other hand, a secure supply of the traditional aroma varieties which they need for their distinctive brands The breeding process takes many years to develop a new variety to commercial viability. Thus, much work is now being undertaken to develop research techniques to shorten this timescale. These advanced research techniques, at the molecular or cell level, may indicate alpha acid content or susceptibility to disease at an early stage of plant growth and only plants that have desirable characteristics need be grown in the field.

An important element of the breeding programme is selecting for disease and pest resistance. At the moment existing commercial varieties have a greater or lesser susceptibility to Verticillium wilt, powdery mildew and downy mildew but none is resistant to aphid attack. Sources of resistance to hop aphids have been discovered and to produce hop varieties tolerant to all of these problems would be a major breakthrough. This is one of the objectives and challenges for HRI-Wye. There are those who believe that by the year 2020 all the hops grown in England will be dwarf varieties or at least low trellis, pest and disease resistant, acceptable to brewers in terms of alpha-acid and cost; some will impart the traditional flavour and aroma of Goldings to beer. Time and financial investment will tell.

The innovative programme being developed for the needs of the 21st Century, by HRI at Wye in Kent, is funded by the hop industry (National Hop Association of England and brewing companies), DEFRA, The East Malling Trust and other sponsors. Its aim is to keep the English hop industry ahead of overseas competition by concentrating on the needs of the hop users, the brewers.